Thoughts on the Minimum Weight

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Today’s topic regards minimum weight for balances and is based on information from the U.S. Pharmacopeia (USP), an organization that makes standards to ensure the quality of pharmaceutical products. The following is a summary of the contents of USP Chapter 41 Balances.　

“Unless otherwise stated, when substances must be accurately weighed for analysis, the measurement uncertainty (random or systematic error) of the weighing equipment used must be no larger than 0.10% of the measured value. For measurement uncertainty, repeatability is assessed by weighing one test weight 10 times and is satisfactory if twice the standard deviation of the weighed value, divided by the nominal value of the weight used, does not exceed 0.10%.”

The standard goes on to say that the minimum mass measured by a weighing instrument should be 2000 times the repeatability (defined by standard deviation σ) that is obtained through 10 successive measurements of the same, unchanging mass, such as a standard weight.

The wording of this standard appears to be incredibly difficult to understand at first glance. What it states, however, is simply that, considering 2 sigma (deviation of a 95% confidence interval), measurements carried out with this deviation below 0.10% are considered satisfactory for ordinary weighing.

However, is there any meaning to deciding a standard precision requirement for all measurement and weighing occurring in different situations? That is, for measurement and weighing sites, generally the required precision for each site is different. It is readily apparent that the required uncertainty for dealing with gold is vastly different than weighing candy. It is also necessary to consider what is lost and what is gained as a result of single-minded focus on pursuing precision. In particular, microanalysis is an industry that has the some of the strictest requirements for weighing in modern society, requiring minimum weight at the milligram level. For these measurements, a deviation of 0.1% for a weight of, say, 1 mg would require a repeatability of half a microgram (1 mg / 2000 = 0.5 μg). The only type of balance with the capacity to guarantee such minute repeatability is an ultra microbalance. The measurements required by this standard at that infinitesimal scale would dictate the purchase of such an ultra microbalance. Unfortunately, these balances are not only extremely expensive but also incredibly difficult to use.

As I mentioned previously in Development Story 38, maintenance of the weighing environment and proficiency in weighing operations are of utmost importance. Currently, what seems most problematic is the fact that balance manufacturers highlight only the importance of the minimum weight and the standards for it. They then sell balances and afterwards leave the problems concerning errors arising from installation environment and how the balance is operated unsolved. They make no attempt to resolve these problems. In the end all that remains is an abundance of expensive dust-covered paperweights that happen to be called “ultra microbalances”. This lack of support is responsible for the deterioration of trust in weighing device manufacturers.

Under these circumstances, figuring out how best to deal with these problems at the places where these balances are actually used has become quite an issue. Although the minimum weight was first defined as the standard deviation times 3000 and now has been revised to 2000 times the standard deviation. This only served to prove the standard was a theory only on paper that failed to consider the work actually being done at the various laboratories. From my experiences abroad and at domestic laboratories, there were very few places that I thought had suitable weighing environments for microbalances, namely some public institutions and balances manufacturers in Europe and research organizations in Japan. In elemental analysis a calibration curve is used on the sample to be measured and always gives a result. However, this requires confirmation of the precision of the device used for this analysis.

In the past, the minimum display of measurement devices including analytical balances was used as a reference value and there was an unspoken rule that measurements were taken from the next most significant digit from the minimum display. The reason for doing this was that balances had many display digits and were subject to many disturbances from operation as well as from the environment which made it difficult to determine stable weights from the minimum display digit. People realized that 10 times the minimum display was required as the determinable display. There was also rule that stated that 1000 times the determinable display would be sufficient to obtain results whose uncertainty is within 0.1%. With a repeatability of 3 micrograms, the 3 sigma value is 10 micrograms allowing for accurate weighing of 10 mg samples. This means that the current minimum weight is nothing more than the standardization of the previous unspoken rule of measurement.

Given all that has been said above, while the idealistic minimum weight standard may be reasonable for general purpose balances or general analytical balances with 0.1 mg minimum displays, it is not appropriate for microbalances. When it is not necessary to confirm 0.1% at the place of analysis, instead of blindly following the standard, a flexible response that takes into account the necessary weighing precision is vital. Using the example of balance repeatability, if the minimum weight is redefined as 1000 times the standard deviation balance users would determine that what really should matter is that weighing precision is suitable to one’s intended purpose without getting caught up in a spec war about microbalance repeatability. Also, given similar expenditures, instead of spending 100% of the purchase cost on the balance itself, there is value to be had in investing in creating a worry-free weighing environment through the proper maintenance of the measurement environment or participation in training that ensures proper weighing techniques.

Operation of Microbalances for Elemental Analysis

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Microbalances with minimum displays of 1.0 to 0.1 μg are used in the inductively coupled plasma (ICP) method for elemental analysis. One microgram (μg) is equivalent to a one-millionth of a gram. Common reasons that a microbalance is used are that elemental analysis is quantitative and small samples of a few milligrams are used.

A few years before the start of sales of the microbalances (with minimum display 1 dig = 1 μg) developed in my division, I had the opportunity to visit facilities that carried out elemental analysis. Each time I visited these facilities I gained valuable insights and experiences. In balance development and production, balance performance is always inspected with standard weights. However, in elemental analysis an unknown sample powder is weighed each time and disparities in performance arise from differences in measured material and the measurement environment.

Performance testing of balances at A&D requires that the balance be 1) placed on an anti-vibration table 2) on a stable and rigid bench 3) with a solid foundation. 4) The measurement room must be partitioned off from the rest of the lab and 5) the microbalance must be placed inside an external breeze break to reduce drafts from air conditioning systems. 6) The temperature, humidity, atmospheric pressure, vibrations and wind speed are to be monitored. 7) The balance must be plugged in for approximately one night and a standard weight is used for inspection. Finally taking into consideration the largest source of disturbance, heat from the human body, 8) a special set of 21 cm tweezers must be used to ensure the technician’s hands do not enter the breeze break when confirming repeatability with the 1 g weight.

If proper attention is paid to the measurement environment as detailed above, the repeatability of the BM-20 (22 g capacity, 1 μg minimum resolution) operated manually with a 1 gram weight has been confirmed to be at best 1.2 μg and with this repeatability it is possible to measure to a minimum weight equivalent to 2.4 mg.

Some causes of reduced microbalance performance are from the installation environment and the act of weighing. For the installation environment, the problem is not that the temperature, humidity, or atmospheric pressure is too high or too low but the small changes in the conditions as detailed below. 1) A weak breeze from an air conditioning unit can create ripples of 0.1˚C changes in room temperature imperceptible to humans that negatively impact the display stability of the balance. After deciding to eliminate the source of the breeze by 2) turning off the air conditioning unit immediately before weighing creates slight temperature fluctuations, another cause of display instability. General weighing with balances should be an accurate and agile process. Sources of error caused by the environment on the balance should be minimized, that is, 3) measuring should be done quickly. The door to the weighing chamber should be opened sparingly and the door should not be opened too far, and operations should be kept short to prevent drafts inside the weighing chamber. This phenomenon can be easily inferred from our experience of being in a warm room in winter. That is, when a door is opened more cold air rushes into a room if the opening is large and it is opened for a long time.

Eliminating the effect of the operator’s body heat and breath is essential as the operators themselves contribute the largest sources of error for a balance. We recommend the following for basic operation: 1) Operators should refrain from operating a balance while they are sweating. 2) Operators should wear proper laboratory clothing and refrain from wearing T-shirts as they disperse heat. 3) Tweezers should be used to prevent the exchange of heat caused by putting fingers inside the balance enclosure.

Fig.1　AC on, no external breeze break
Fig.2　AC on with external breeze break

The above graphs show the effect of air conditioning on the performance of a balance. The same balance was used in the same location for both measurements. The horizontal axis shows a 24 hour time period, the red vertical axis shows temperature change and the black vertical axis shows the standard deviation for a 20 g gram internal weight measured 10 times. That is, each point is the standard deviation of ten consecutive measurements. The graph on the left has negligible temperature change and stays between 26 and 25˚C but the repeatability averages 5 μg and crosses 8 μg in 8 places. The temperature change is larger, 1.8˚C, for the graph on the right; however, it is much more stable with repeatability averaging 4 μg and at worst reaching 6 μg.

The cause of this difference in performance for the balance was confirmed to be tiny ripples in temperature. These are shown by the 0.1˚C temperature fluctuations occurring after 19:00 on 7/12 in figure 1. Although the single day change in temperature in figure 2 is large, there are no temperature “ripples” and the temperature change occurs steadily. The reason for this is the balance in figure 2 was enclosed in the AD-1672 Tabletop Breeze Break causing the small fluctuations from the AC to disappear, allowing the temperature to transition gradually. This data demonstrates that balances are stable during gradual changes in temperature over the course of a day and weak against slight temperature fluctuations over short durations. The external breeze break is an effective countermeasure for drafts caused by air conditioning systems.

Fig.3　Typhoon no anti-vibration table
Fig.4　Typhoon with anti-vibration table

Figures 3 and 4 are graphs from two microbalances used in the same location at the same time during a typhoon. In the graph on the right the AD-1671 Anti-vibration Table is used whereas in the graph on the left it is not. Winds from the typhoon cause the building to sway in ways not detectable by humans and cause the repeatability of the balance to deteriorate. However, the passive vibration canceling ability of the anti-vibration table has proven effective as a countermeasure for the imperceptible movements of buildings. Active vibration canceling tables such as the ones that use air suspension are known to shake the balance ever so slightly leading to unstable measurements.

The above graphs illustrate the necessity of understanding and analyzing the various disturbances and show that balances will have greater stability when the correct countermeasures are used for those disturbances. In general, the change in temperature for a day should be kept within 4˚C and the short term (30 minute) temperature change should be within 0.2˚C. Humidity should change no more than 10% in a day and atmospheric pressure should be within 10 hPa. Vibration and wind should be kept to a minimum.

Monitoring environmental variables is critical for ensuring balance performance and as a result we developed the world’s only environment logger capable of simultaneously measuring and recording temperature, humidity, atmospheric pressure, vibration, wind speed and weighing values. Furthermore we have perfected “AND-MEET”, an environment evaluation tool used for the 24-hour monitoring of the balance and environment. The figures 1 to 4 were results of AND-MEET, and by installing and using these instruments and tools in the actual points of use of microbalances, we can evaluate the installation environment and propose improvements for each laboratory. Through the introduction of this established method, these tools provide the technical support to ensure that the microbalance can be used worry free. Excluding operation methods, we have perfected the method of evaluating and proposing improvements to the measuring environment.

After inspection of the remaining weighing operations, the following countermeasures were drafted. The required minimum weight for elemental analysis is around 2 mg and a weighing tolerance within 0.2 mg (10%) is considered satisfactory during sampling, but to ensure the precision of the analysis results 2 mg±10 μg is desired. In general, samples are weighed on quartz or platinum weigh boats up to 3 times, but the minimum display of 1 μg is not required for all processes. Accordingly, the following three steps can be suggested: 1st Weighing: Individual boats are left in the weighing chamber to adjust to the temperature and weighed to the nearest 1 μg. 2nd Weighing: The sample is weighed together with the boat in the 0.1 mg range or 0.01 mg range. 3rd Weighing: The boat and sample are left in measurement chamber to adjust to the temperature before the final measurement in the 1 μg range. By using this method we are proposing that when measurement in the ug range is unnecessary, measurement should be in the larger ranges and additionally from the measurement in the microgram range for the initial tare and final value the sample value can be obtained from subtracting the weight in 3rd weighing from the weight in 1st weighing.

This method reduces the number of measurements required in the 1 μg range and potentially shortens the measurement time necessary for the 0.1/0.01 mg estimates. This in turn reduces the change in temperature inside the weighing chamber allowing for stable measurements. This proposed measurement method assumes that the time the chamber door is opened is as short as possible and the door is closed before each measurement to minimize changes to the interior of the chamber.

Even through adopting these methods, the minimum weight obtained from the 2.5 μg repeatability in the specifications for the BM20 is 5 mg (2.5 μg × 2000＝5 mg). Determining sample weights under 5 mg require an ultra microbalance with dig = 0.1 μg. However, preparing an environment for measurement with an ultra microbalance is extremely difficult. I’ve seen many ultra microbalances in laboratories that I’ve visited collecting dust from disuse. As this has become quite long I will wait until next time to expand upon the problem of minimum weight and microbalances.

Development of AD-1641: Air Flow Logger

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A&D has developed an air flow logger capable of detecting breezes with speeds below 1m/s. For this development story I have put some material together on the background behind the development the air flow logger and also some market information related to safety cabinets.

A few years ago we developed and started selling the BM series of microbalances capable of microgram measurement. The BM series includes our flagship products, the BM-20 and BM-22, which are currently the only microbalance made in Japan. We have developed products like the BM-252, a world-first device capable of a minimum resolution of 10 μg through the full range of its 250 g capacity, that still remains the only of its type in the world.

When designing the BM series, I traveled around gathering information from laboratories and dealers. At that time, many microbalances found in labs were literally collecting dust. I inquired as to why these microbalances that cost upwards of 2 million yen were being left unused and was told that they are so unstable that they are useless. Meanwhile, I was also reminded of the fact that about 10 years ago a domestic maker began to offer microbalances only to be inundated with complaints and quickly retreat from the market. I think that in the background of all this if Japanese balance manufacturers are going to sell microbalances, it is their responsibility to prevent problems that become potential nuisances for the customer in the end.

As a result of visiting various labs I found that microbalances were often placed in unsuitable areas such as on a central table in the laboratory near areas of frequent foot traffic, directly below the vent from an air conditioning system or in direct sunlight near a window. This led me to decide that when selling a microbalance, it was essential to measure the temperature, humidity, atmospheric pressure, vibration and wind speed to show that the location where the balance was to be installed was appropriate.

After some contemplation I realized it was possible to evaluate the environment by monitoring the measurement values of a balance over a long time as balances themselves are sensitive to environment factors. Going one step further we determined that by simultaneously measuring the other environment factors, the source of weighing instability could be ascertained. In order to do just this, in development we came up with a method of obtaining repeatability. This method worked by periodically raising and lowering the internal weight, using the zero and measurement value to determine the span value repeatedly and finally using these span values to calculate the repeatability. We also found it is essential to measure environmental factors contributing to error (temperature, humidity, atmospheric pressure, vibration and wind speed).

This method eventually became A&D’s measurement environment evaluation tool, “A&D-MEET”, which entered the market when the BM series was first sold. However, at A&D there were some issues with using MEET. This was because MEET would incur labor costs that we were unsure of how to consider appropriately. Sales thought the process was too high-maintenance as it requires 1) setup of the balance and running MEET, 2) a return trip to gather the data and 3) another return trip to explain the results. They claimed this process was ineffective for business.

I insisted that as a service fee for using MEET around 100,000 yen should be the established price. I also added that repeatedly visiting the customer could lead to future business opportunities. However, the main reaction I received was that A&D was a company that sold physical items and had no business gambling on services and also that no customer would spend 100,000 yen on an intangible thing such as running MEET. This lengthy debate within the company ended in futility as in the end the price of things is determined by the people who buy them.

Four years has passed since MEET was proposed and A&D’s microbalances are reliably sold by sale representatives with sales continuing to increase every year. From the perspective of the researcher when buying an expensive microbalance the biggest risk is not being able to use the device. Therefore it is easy to conclude 100,000 yen to be a reasonable price for a tool that can avoid or reduce such a risk. Additionally, even if they do not ask for MEET when the balance is installed researchers will feel a sense of safety more than anything else when we explain that we are prepared to deal with any measurement troubles beforehand. Moreover, when beginning to sell microbalances we also began sales of independently designed breeze breaks as well as anti-vibration platforms and balance tables as tools to improve the measuring environment to support the microbalance market.

Now back to the main topic, aside from evaluating the environment where an analytical balance is used, the measurement of breezes in labs can be used in the following cases: 1) Measurement and recording of the wind speed at the entrance to a fume hood or balance enclosure, 2) measurement and recording of the holding environment for animals and plants, 3) measurement and recording of the air flow in a cleanroom or laminar flow cabinet as well as the measurement and recording of transport and usage environment of precision devices. When the BM series first came on sale, there was no device in the world that could simultaneously measure and record environmental factors that affect balances such as temperature, humidity, atmospheric pressure, vibration and wind speed. And the addition of the capability to measure low-velocity breezes has culminated in the AD-1641 Air Flow Logger. The AD-1641 can be used to simultaneously record up to 10000 data sets from 6 different measurements, including environmental factors (temperature, humidity, atmospheric pressure, vibration, and wind speed) affecting places from laboratories to production facilities, and measured weight data.

Fig. 1 below shows AD-1641 placed at the opening of an AD-1673 balance enclosure.

AD-1641　Air flow logger installed in balance enclosure
Fig.1 AD-1641 Air flow logger installed in balance enclosure

I believe that for instance if the AD-1641 is used for the required air flow measurement of all types of safety cabinets, it will serve effectively as an environment recording tool and guarantee the safety and security of researchers working on analysis and materials development as well as producers of materials.

I have experienced firsthand the difficulty of selling world-first products from Japan and yet, as long as I have time, I will continue to strive to design and sell successful products that not only add value but also express creativity.

Development of the GX-A/GF-A Series

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For this installment of the developement series I would like to share some details on the ongoing development of the successor models to the GX/GF Series of Precision Balances released 15 years ago.

These top loader balances have the mass sensor mechanisms and the circuit board housed inside a case with the weighing pan placed on top as the name suggest. The minimum weighing displays are 1mg, 10mg, and 0.1g and the weighing range is between 200 grams and a few kilograms. The ratio of the minimum display to the capacity is approximately 100,000~1,000,000 to 1. These balances are capable of high resolutions and sensitivities and as such make up a key market area for weighing instrument commodities and are used in a wide range of applications from the inspection and quality control of parts on a production line for industrial products to experiments and research at universities. Also the exceptional cost performance and user-friendliness of these balances make them ubiquitous in biological and medical research as well as food and materials development laboratories.

I have mentioned before that in the year 2000 when the original GX/GF was developed, three or four competitors had already proposed new “mono” (single unit) structure mass sensors. However, to me following this idea would only entail playing catch up to other companies. Moreover using a specialized “mono” structure would limit the processing methods, requiring capital and investment in production facilities. The large initial investment was a cause for worry that led us to conceive the super hybrid sensor (SHS) with a method of combining modular high precision parts instead of having a “mono” structure. I have written previously about the research leading up to our unique hybridization and realization of the actual sensor.

When we were developing the SHS, Japan was at a high level of technological sophistication and fortunately we had maintained long-standing cooperative relationships with manufacturers of high quality parts. They boldly set out on the machining process of the Roverbal structure, which was the key component of the SHS that we planned. This would result in the production of specialized components being done with general processing machinery turning the hybrid structure into reality. Some time has passed since the development of the original SHS and even now, the GX/GF series equipped with the first SHS remains securely as the leading balance in Japan. At the same time the SHS has evolved and is currently finding uses in devices from microbalances to industrial balances and sensors for moisture analyzers.

When the SHS was being developed, our competitors were focused on mono structure designs so proposing a hybrid structure was met with significant criticism from within A&D, with people suggesting it was a hopeless endeavor. However, to use an example from the automotive industry, most customers don’t really care whether the camshafts of a car are SOHC or DOHC, or if it is a turbocharger or supercharger, or if it’s a diesel or hybrid vehicle. What people actually care about is the comfort when driving (acceleration, stability, collision safety, space, storage, convenience) and fuel efficiency, and whether they are commensurate with the initial investment and required maintenance fees. In other words, the materials that are advertised as relevant to cars are only means, not the ends..

Even for balances, if the performance (weighing stability, response speed, usability) is good then debating the method to obtain that performance is meaningless. We developed SHS as the mass sensor that would give the GX/GF series the fastest response time in the world and make maintenance simple and cheap while reducing the cost of components.

Although the GX/GF has become the market leader in the past 15 years, we planned a complete model change and started development of a newer mass sensor to make a more user friendly product 3 years ago. This was due in part to the rapid technological improvement in electronic parts. This new model would be the last mass sensor that I personally would develop after working on 6 types since the first HX in my 27 years of employment at A&D. I have therefore planned a product that should remain at the top of its class for a decade from now and also have proposed solutions to the many performance inhibiting problems discovered with the mass sensor that led to dead ends in development. During such dead ends, engineers will be put to the test. The conventional way to continue development during these times is reshuffling people because engineers that begin to list reasons why something can’t be done cannot be persuaded to change. More than 2 years was required to get the desired performance and in that time an engineer has quit due to differences in opinions.

In our current project we ended the shaving process for corner-load adjustment while following the proposed SHS hybrid structure and adopted a structure that uses screws for corner-load adjustment. We equipped the sensor with a feature that can announce when there is an excessive load. This is to protect the mass sensor from damage for when automated production machines are used, as the load applied by automated machines can reach around 3 times greater than when the balance is loaded manually. In addition, we adopted a new leveling mechanism and function that allows measurement of flow rates of liquids. These features are a new plan focused on the place of use and have not been included in any balance up until now.

I would like to explain the technical specifications of the new additions in further detail over several installments. This time I will cover the composition of the device and the alarm for excessive loads.

The measurement display area is larger in the new GX/GF and the display method has been changed from VFD to reverse backlit LCD. The large white characters make the display easier to read. We have also added a light to the spirit level to facilitate horizontal adjustment in darker areas.

GX-A/GF-A Series

Now, I will move on to the overload warning. Balances are calibrated with weights of known mass at the place of use/installation. The purpose of this calibration is to compensate for the acceleration due to gravity which differs depending on location. The force F = M0 × G0 where M0 is the mass of a known weight, G0 is the location’s gravitational acceleration is balanced with the electromagnetic force through the intermediary of a fulcrum. When a load is added a beam moves and its displacement is measured by a position detection unit with an infrared sensor, and the current of the electromagnetic unit is controlled so that the beam comes to the same location. If the current is controlled, the load on the pan and the Lorentz force produced from the electromagnetic unit can be put at equilibrium and an electromagnetic force proportional to the added load is produced.

We call using the electromagnetic force to balance the weight (mass) on the pan the electromagnetic equilibrium method. Currently almost all top-loader balances and analytical balances use this method. In the electromagnetic equilibrium method the mass of an unknown object is determined by balancing the force (current) produced by the electromagnetic unit with the unknown object.

With this method, the position sensor output changes proportionally with the load, and afterwards the closed controlled beam returns to its original position by the electromagnetic force. The displacement from the position sensor changes with the load. If the derivative of that displacement is taken with respect to time, the velocity of the beam can be obtained and from that another time derivative is used to find acceleration. We found that the change in the position sensor when the impact load is added shows the displacement of the beam when the impact load is transmitted and if the acceleration is obtained from the second derivative of position, the static load equivalent applied to the mass sensor by the impact load can be evaluated.

An experiment to prove our hypothesis showed that when a person places something on the balance pan with their hands there is a three-fold difference in the impact that the mass sensor receives compared to when the same mass is placed on the balance pan with a pneumatic actuator. That is, we showed that 1kg (1G) loaded by hand, registers as a load of 3kg (3G) even after adjustments by air cylinders or other devices. Giving the function to process this data to the balance itself and showing the result of that evaluation on the display unit will allow balance users to see that the weight is overloading the system.

In the past there were some instances of balances built for production lines for large automotive manufacturers becoming damaged after a certain period of time. To remedy this, A&D, the automated machine manufacturer and the end user conducted an investigation to determine the cause of this problem. The investigation found that after a short amount of time the mass sensor unit became damaged for the balances at all of the manufacturers. At this time it was speculated that if the balance could determine and transmit its condition, developers could plan against damage to the balance before it happened. We determined that by displaying the equivalent load experienced by the mass sensor to the user and issuing a warning about how the balance is used, preventative measures could be formulated to protect the balance.

The GX/GF-A is the first in the weighing industry capable of evaluating impact loads and I believe it will find many applications on the production line as a versatile weighing instrument due to its quick response speed and stability.

Development of Balance for Animals

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Automatic scale for animals（AD-1642A for mice）

Animal testing is used to accomplish the crucial task of evaluating the safety and effect of medicine before testing on humans occurs in the development process for new medicines. At facilities that perform these tests many tools ranging from balances for measuring weight to microscopes for observation are used for analysis.

In the past analytical experiments were commonly performed on animals to investigate the weight change of internal organs after medicine was administered as well as the biological responses of certain organs. However, an increased focus on animal welfare has led to a strong push toward reducing live dissections that accompany analytical experiments.

In recent years there have been ongoing attempts to measure the behavior patterns that indicate an animal’s health condition as well as changes in the voluntary activity of animals. This includes determining the behavior patterns and symptoms of the animal’s psychological state to try to see the effect of the drugs on the animal’s behavior. These methods are linked to the movement towards conducting appropriate evaluations and drawing proper conclusions on the effects of medicines including the mental state of a person when they are prescribed medicine.

It is becoming apparent that even when medicine is administered to people there may be psychological impacts that cannot be understood from only the response of the internal organs. Keeping this in mind, analyzing quantified phenomena such as animal behavior patterns and determining the effect of the medicine from those results is leading to methods for evaluating the comprehensive response on an individual or group of organisms.

Even though a medicine may cure a person’s illness it can also cause a reduction in that person’s quality of life (QOL) or in the most extreme case curing the disease may cause the person die. Recognition of these ideas is spreading among not only the pharmaceutical and medical industries but also among the general population.

In the past a device that measures the movement of animals by using the change in electrostatic capacitance was proposed as a way to measure animal behavior. Recently there have been attempts to quantify voluntary exercise using IR sensors and CCD cameras to capture animal movement.

Using these methods, digitized data from counting the number of movements between virtual areas on the floor of the animal’s cage and also from using light to count the movements between areas are used as the basis for measurement of voluntary exercise and the animal’s activity. However, quantifying animal movements observed from optical devices into digital data is a difficult problem among other problems such as poor measurement method compatibility and poor repeatability.

Many people have expressed the desire to measure both age-related weight gains of animals such as mice and weight changes caused by administering medicine all while measuring animal’s spontaneous movements over a period of time. There is a desire to make successive weight measurements on an animal without direct human intervention especially in the case of assessing the effect of pollutants on the body. Specific requests are increasing for improving safety issues with cross contamination such as with viral infections between humans and animals and improving experimental accuracy by lowering contact between people, the largest source of interference, and the test animal in the process for raising animals.

As a response to this latent demand we developed a scale that can automatically weigh mice and record the data. On this scale we placed a balance under the mouse’s cage and used a vertically extended pan support to place the balance pan the inside the cage.

By placing only the balance pan inside the cage, the measurement value when the mouse is on the pan (loaded value) and when the mouse is off the pan (zero point) can be calculated. By subtracting the zero point from the loaded value the weight of the mouse can be identified and by carrying out measurements over a long period of time data for weight change over time can be obtained.

Our newly developed automatic scale for mice is shown in figure 1.The balance for this scale is on the bottom, enclosed by a case. The mouse cage is placed on top of the case. There is a hole on the floor at the bottom of the cage. The balance pan goes through this hole as part of the structure inside the cage. The output from the scale is recorded as continuous measurement data and that data can be sent to a PC and analyzed. Additionally, wireless transmission of data is possible if the measurement environment permits.

From the time-series monitoring of the mouse’s weight, that is measuring the time and frequency that the mouse is on the pan and also the amount of variation in its measured weight, we found that we could obtain not only the mouse’s weight but also important reference data for the amount of voluntary exercise and activity. Figure 2 shows data for a black mouse that weighs about 30g inside the cage for 90 minutes. On the graph the horizontal axis represents time and the vertical axis shows weight in grams. This mouse was full of curiosity and once inside the cage actively investigated the surrounding for the first 50 minutes. Afterward it stayed on the measurement pan and refrained from moving around much as shown in the graph. The graph shows the mouse’s weight on the pan as about 28g and displays zero grams when the mouse is off the pan. If, for instant, there was food or feces on the pan the mouse’s weight could still be calculated from the difference of the displayed weight when the mouse is on the pan and the “zero-point” weight.

Additionally, from being able to determine the frequency and amount of time that each mouse is on the pan and making some calculations an estimation of a mouse’s voluntary exercise amount is possible. Experiments with different mice put into the cage show large differences in the individual movements of each mouse.

Weight change for black mouse in cage for 90 minutes
Fig.2 Weight change for black mouse in cage for 90 minutes

With our newly developed automatic animal scale the previously difficult task of conducting sequential weight measurements is now possible. Furthermore, it was determined that by monitoring the change in weight over time, it is possible to evaluate the effect of medicine and other materials on animals. I believe our scale can be used as a device for measurement and analysis in fields outside medicine evaluation, for example, evaluating an animal’s individual activity levels, analyzing behavior patterns, and evaluating the effect of habitat aspects such as food, water, temperature, humidity, vibration, and wind on animals.

I would like to use this automatic measuring technology as a base to continue active development of various new products that can objectively evaluate the behaviors of animals.

Development of Production Line Microbalances

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Weighing instruments have a long history of use in part quality control and are recognized for their simple, cheap, and precise detection of defects including missing internal parts. Accordingly, precision balances were brought to the quality control and quantity management postproduction processes and have become essential for effective quality control. Next, from around 30 years ago general-purpose precision balances having 10 mg readability became more common mainly on bearing production lines. This was largely attributable to the fact that quick response balances with response times as low as one second came about and realized takt times of one second required on production lines. Latent demand propelled development of new quick response balances which led to the ability to perform complete part inspections and an increase in the frequency of weighing instrument use on production lines.

In my third year at A&D, I brought the HX series, which I developed from a weight sensor, to the market with an extensive set of design specifications that mirrored the society of the late bubble period. The HX series was a highly-functional, high-priced product compared to the general-use balances of the time but was not well received by the post-bubble market and ultimately failed. Despite its failure the HX series was the only general purpose balance to achieve one second response time in the balance industry at that time. Ten years later in 2000 we developed the GX series, the second generation of successor to the HX series and traveled to demonstrate this new product to our customers at large companies. I was surprised to find that manufacturers frequently using the HX series were strongly opposed to the discontinuation of the series. It was here that I realized the extent of HX series adoption on production lines. I find it amazing that it took me, the development manager, the entire 10 year period from product launch until its discontinuation to realize such a simple thing.

This realization helped me understand the importance of frequently turning to the market. I reflected on the widely-used development stance of the time that offered little perspective on the outside world. Since then when the opportunity presents itself I do my best to visit the sites where the products are actually used. I also came to realize the difficulty of obtaining market information since our company did not do direct sales.

Today weighing instruments from the level of general purpose balances to that of analytical balances measuring units as low as 0.1mg have become commonplace on the production line. Also in the past few years devices that weigh to the millionth of a gram called micro balances present new opportunities for quality control on the production line.

Microgram sensitivity has become important in production for three reasons: (1) the saturation of the large liquid crystal market and the booming smartphone market have caused the amount of resist ink added to small liquid crystals to reach the 0.1　mg　(100　μg) range, (2) the miniaturization of electronic components has led to a reduction in the amount of IC sealant and soldering paste, and (3) there has been further miniaturization of bearings for storage and other devices. Behind all of this is the far-reaching issue that for Japan to survive in new markets it must guarantee superior quality control for its products.

In the situation described above, Japan, Korea, Taiwan monopolize the design and construction of production lines containing weighing instruments and the final placement of the line is almost inevitably China.

Many experts understand that microbalances display values tend to be unstable. However regarding why they become this way the common answer vaguely states the high sensitivity of the device is the source of the instability and doesn’t specify any further sources. This reality created a situation in which even when the sources of instability needed to be remedied where these balances are used, no corrective action could actually be taken, leaving the manufacturers of the balances to find a solution themselves. Nevertheless, the industry has long seen no manufacturer or balance related technological report that proposed any reasonable solution to the problem.

It is a contradiction that weighing and measuring instrument manufacturers do not measure the environment where the device is placed. To remedy this we looked into this idea of measuring the measuring environment. As a result, we came up with the idea of first recording weighing data over a long period of time while simultaneously taking the temperature, humidity, pressure, and vibration data of the weighing environment, next calculating the repeatability from the consecutive weighing results, and then graphing the data in order to hit on the cause(s) of the weighing instability. Through the rather upside-down thinking of drawing on the instability of the balance itself to identify its environmental causes, we found that it was possible to determine all sources of instability through monitoring weighing and environment data for 24 hours. This method became the basis for our weighing environment evaluation tool called “AND-MEET”. Through using AND-MEET and collecting and analyzing data the following could be determined to influence measurement: far away events such as the recent earthquake in Nepal 5000 kilometers away and influence from tectonic movements on the global scale, closer sources such as turning the air conditioner on and off, movement of people and trucks, the passing of low pressure air, heat from devices like electric furnaces placed in the room, and structural issues in the building where the measurement instrument is placed. After understanding the sources we could easily find ways to deal with them.

However, finding a way to handle instability caused by passing of a low pressure system proved to be our most difficult problem. Our newly developed device for production line weighing, the AD-4212D series, includes a model with a minimum display of １μg and improved display stability. Display stability has been a problem with the existing products and fixing it was the most important of our development goals.

We were able to plan against disturbances such as temperature, humidity, and vibration. However, in our approach to correct issues caused by the approximation of a low pressure system we found that the standard deviation of the repeatability which should be 1.2 μg worsened to over 10 μg. We believed the source of this problem was the building being shaken by the strong winds accompanying low pressure systems. So we used the AD-1687 Environment Logger to repeatedly evaluate the environment. Unfortunately, there was no change in the vibration sensor, sensitive to one Gal. Even when there was no vibration in the building occasional instability in the weighing instrument was confirmed. The instruments were relatively stable during the summer but data taken a half year later in winter showed an increase in the frequency of instability. Finally, we identified that the wind speed as announced by the weather station itself would worsen the repeatability. However, even if wind blows directly towards the weighing instrument, with proper protection such as a breeze break there should be little effect. Furthermore there was no reason to think wind from outside could enter the partitioned rooms housing the balances.

In the end we found that minute pressure fluctuations inside the room attributed to the reported wind speed outside and pressure deviations caused by the airtightness of the casing for the weight sensor contributed to a variation in the instrument’s zero point. I plan to explain the details of our countermeasures for this problem at a later date, but after their implementation the new line of weighing instruments guarantees stable measurements at one microgram and ensures high precision with repeatability of 1.2 micrograms even if the wind speed is 4 m/s (or wind power 2) as shown in the attached graph. It has already been two long years of development for the AD-4212D.

A significant amount of time was required to ensure high stability at the one microgram level. Still, one technological breakthrough has eventually amounted into a tangible product as with the AD-4212D. I hope this weighing instrument, as a high stability analytical balance like none before, will effectively ensure the performance and quality of products manufactured on production lines and thereby contribute to productivity and quality improvements in Japan’s specialty of precision instrument production.

Fig1:AD-4212D Controller (display) and weighing unit
Fig 2：AD-4212D　AND-MEET data
Repeatability at wind speed 4m/s averaged1.3 µg
AND-MEET and Earthquake in Nepal
    Fig3：AD-4212D　AND-MEET data from time of earthquake

Fig 3 shows AND-MEET data for the 24 hours between 9:00 AM on April 25th and 9:00 AM on April 26th, 2015. Repeatability worsened due to the earthquake in Nepal but we confirmed no problems in balance function even with the maximum wind speed of 6.8 m/s.

10 mL Pipette and Charging Stand Development

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As of April this year, the MPA series of electronic pipettes, which took two years of development, have been on the market for one year. Putting this new product out on the pipette market this past year has been quite the challenge. I traveled from Kyushu to Hokkaido and even abroad to market the product in development as it was decided that the MPA series would have difficulties penetrating markets still critical of electronic pipettes on our existing sales routes.

It was quite demanding to carry out sales promotions while making progress with our various development projects. The only consolation was that I was determined to take responsibility for the results of my plans. The fact that the development of weighing instruments stagnated as a result of investing in pipette development is something I ruminate on time to time.

I was worried that perhaps the MPA series would not sell more than a few hundred units in the first year. However, once sales began my outlook became more positive. I was also surprised at how dramatic the drawing power of our electronic pipette lineup was at exhibitions. Although the real sales expansion has yet to begin I learned there was significant demand for charging stands and multichannel and 10 mL pipettes from visiting the various markets.

Using this information we proceeded to simultaneously develop a linkable single pipette charging stand and a four pipette charging stand. We also produced a charging hanger that allows a device to be placed anywhere as well as a hanger without the charging feature.

Our next development priority was to make a 10 mL pipette. We had two reasons for our swift development of the 10 mL pipette. First the goal of the MPA series was to replace existing sales of manual pipettes, which currently prevail in the market. Secondly some operations on manual 5 mL and 10 mL pipettes place a burden on researchers as they require a great deal of effort to use because of the large diameter of the cylinder and long movements of the piston.

To increase the volume of a pipette, it is necessary to increase the size of the piston. However, if we were to make our existing MPA-1200 piston larger the internal radius of the O-ring that seals the piston would become too big, and the required operational force would exceed the output of the motor. Additionally enlarging the inside diameter of the O-ring would increase the risk of air leakage. So we introduced U-packing (a component with a cross section that looks like the letter ‘U’ and is often used in hydropneumatic cylinders) to the piston side. My six years of experience with a pneumatic equipment manufacturer helped us make this change to the specifications.

MPA-10000 and Charging stand for single MPA

It is from myriad experiences that people become better able to adapt to challenges that lie before them. Below I’d like to take some time to tell a personal story. When I was in college I went to RIKEN, an independent research facility, for my graduation research. At that time, my lecturer at Nihon University, Dr. Takamatsu, was also a researcher at RIKEN. Through him I was given the opportunity to join the Biological Macromolecular Physics Laboratory at RIKEN. My lab manager was Dr. Fukada who would go on to be the director of RIKEN. I was in charge of experiments dealing with the piezoelectric properties of PVDF (a fluorocarbon polymer). The reason I chose RIKEN was that compared my school in Setagaya, Wakō, where RIKEN is located, was closer to my home. Also at that time I wasn’t particularly fond of the school system. As a student who never studied hard and had no major ambitions I was a burden on RIKEN and must have caused them many problems.

Somehow I completed my graduation research. When I was searching for jobs Dr. Takamatsu introduced me to a manufacturer of blood vessels made from fluorocarbon polymers. Not wanting to be a cog in a large cooperation I had the desire to work for a middle sized corporation, so I applied, took the test and interview, and was hired to that company.

Immediately after completing introductory training I was dispatched to a subsidiary facility established three years prior in Okayama. At the interview I was asked “How do you feel about working in Okayama?” to which I responded that I had no problems. Afterwards I found out that out of the 20 people who joined the company at that time, the two that were sent to Okayama were the only 2 that said they would be comfortable going to Okayama.

The thing that was most surprising to me about my dispatch location was that even though it was on a major train line, trains only came to the closest station once an hour. In front of the station was a rundown inn among some residences. After transferring in Okayama I was the only person on the train that led to the inn on the evening before my first day of work. After 30 minutes of riding through the pitch-black night loneliness finally got to me and I began to wonder if I had made a mistake coming to this remote place. Apparently the coworkers waiting for me at the inn thought I had quit since I arrived so late.

During my time in that rural area I remember one occasion when everyone was talking about how I liked ramen noodles. I thought this was strange but then I remember mentioning to a coworker that I have instant ramen for breakfast when there is nothing else to eat. This was my first-hand experience of how fast news spreads in the countryside. The facility I worked in produced waterproofing and breathable material for hiking clothing. One of my responsibilities was that every morning I had to alternate wearing our products and our competitor’s products, go running, and write a detailed report about the breathability of the products.

I quit the job in Okayama in December of that year. Thinking about it now, quitting only half a year in because I didn’t care for the work or my assigned location was an extremely selfish thing to do. I went to tell Dr. Takamatsu, the man introduced me to that company, that I had quit. He scolded me for quitting the job in such a short amount of time. He said it was inconsiderate to the younger students as many graduates from the lab had taken and failed the entrance exam for that company in the past. Nevertheless, he offered to introduce such an impossible student as myself to another company. But I thought that I would never be able to quit the second time and refused.

I went on to take employment tests for many companies but I couldn’t find one that wanted to hire a person who quit their first job half a year in. Eventually I found myself on unemployment insurance. Actually receiving the money panicked me. I thought that if I keep this up I’ll never have a future and prioritized searching for a new job.

A few months later I found employment in the engine design department in a subsidiary of the internal combustion engine department of Niigata Engineering, the maker of the first diesel engines in Japan. It was a short two years but during this time I used analytical tools based on the finite element method and analyzed the strength of crankcases and connecting rods. This was the time when PCs were starting to appear in the manufacturing industry. So I read a few books and used knowledge I acquired from them as well as the computer given to me to make programs based on the finite element method. I pushed forward with my work assertively and because I did it from my own volition I studied more during this time than I had any time up until this point in my life.

Niigata Engineering Co. Ltd, a company with 5000 employees and their own health insurance union, went bankrupt some years after I quit. I watched Muramatsu, the head of the internal combustion engine department at that time, acting as the last president hold a conference on bankruptcy on television. Although I had seen it coming, I realized that even large company with a long history and plenty of assets will eventually go bankrupt if profits fail to materialize.

I then went on to work for a pneumatic equipment manufacturer for six years. There were two different people in charge of electrical and mechanical designs. As a result, research could not progress on essential components such as rubber seals or solenoids for electric valves. This was because these components are neither electric nor mechanical but rather their own category. And so, right after entering the company, me, with a background in physics and no area of expertise would oversee research on both types of components. I still remember the puzzled look on my superiors face after immediately accepting the job that no one wanted to do.

I took the “Entry Level Rubber Training” course at the Chemicals Evaluation and Research Institute, Japan (CERIJ) in Mukojima to learn about the fundamentals of rubber. Over several months I received practical training starting with the roller-based kneading of rubber materials. I used this newly acquired knowledge and a finite element method program I made to perform deformation analyses of rubber seals. Subsequently I went on to study magnetic circuits independently and produce a magnet field analysis program and applied it to our designs. After a period of time I became the leading engineer in these two fields of the company. It was here that I came to realize that knowledge from a previous job could be put to work on future job.

Thereafter I joined A&D and managed the development of electromagnetic equilibrium balances as an expert on magnetic circuits. In no time at all 26 years passed. I believe that my positive approach to the work given to me has helped me to understand a variety of technical information. I think that short stays at various companies and the experiences gained from the different environments were good for me and in the end helped to broaden my understanding of technology. From my experiences, I believe that especially when one is young and had no work skills, it is almost impossible to find one’s true calling.

If you decide that your work environment isn’t right you should move on to the next job without waiting too long. However once your mind has had a chance to mature and you have even a slight bit of interest in work, you should use that chance to try your hardest. It is not a good idea to set out on an endless search to find true happiness; instead I believe it is important to use the environment given to you and work hard until it feels like your calling.

Even though the fruit of your efforts don’t materialize immediately, you will gain more confidence and eventually be rewarded. I am fortunate that I was able to learn that through my own career.

Now let’s return to the MPA-10000.

In the MPA-10000 we achieved success by using a highly regarded U-packing, lowering the drive force required to move the piston and improving the sealing ability. We originally believed that developing both 5 mL and 10 mL pipettes would be necessary; however, by using the electronic pipette’s high base level of performance to our advantage we decided that we could surpass the function of two manual devices with one electric pipette.

The MPA-10000 demonstrates its true power when used for preparing a large number of samples or reagents for analysis, as it is capable of dispensing 100 μL 99 times from a single aspiration. I believe this device will be incredibly useful for researchers and inspection personnel who before had to bear the brunt of the work of dispensing large volumes repeatedly with a manual pipette.

Charging Hanger for Electronic Pipettes

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About five years ago, at the start of this Development Stories series, I wrote about management tools for micropipettes. In this first Development Story of 2015, I will summarize the development process behind our unique recharging device for our electronic micropipettes. I apologize for the delay in releasing this article, which was almost finished in October of last year, but the last days of 2014 turned into quite a busy time for me, both at work and at home, and progress was stalled for about three months.

Micropipettes are devices that are used without fail in fields that employ analytical balances, which are typified by microbalances. The “electronic” single-channel pipette, which is perceived in this pipette market as being an “unsellable” device, is said to only hold an insignificant 1% market share in Japan. Nevertheless, A&D has daringly set about developing an electronic single-channel pipette as a brand new product and has now released this in the market. Pipettes are uncharted territory for A&D and mean entering a new market for us. In order to compete in a market with no previous results, we designed an original pipette and carefully planned the product development schedule right through to mass production. However, people’s views on this new – and perhaps even foolhardy – challenge of gaining a foothold, and then hopefully a strong reputation, in this pipette market were pessimistic to say the least. We were even told, by people both within and outside A&D who were knowledgeable in this industry, that we had no right to be successful in this new enterprise and it was doomed to failure! Even within A&D, we had hardly any advocates at the beginning for embarking on such a tough journey, and to be honest, not even I had any strong self-assurance that we would be able to sell our newly developed pipette.

A regular thought I have is that development of a new product with previously unavailable functionality or breaking into a new market is a lot like climbing a mountain. When I mention mountain climbing here I am referring not so much to any technical challenges, but the sense of adventure that grips certain people and compels them to venture into the wilds and potential risk. If you define sense of adventure as moving into an unknown field, adventurous mountain climbing means that if your technical ability, strength or ability to reflect upon previous experiences is lacking, you are unlikely to make it to the top. Even supposing that you could make it to the summit, a safe descent is far from guaranteed. For new product development, when attempting development in a new field or developing products with more sophisticated functionality and performance than ever before, your efforts can easily end in failure. Therefore, for both pursuits, it is essential to set your goals properly at the beginning, apply an indispensable risk management approach to preliminary research and target achievements, and acquire a new set of skills and techniques. It is also vital to be able to handle a variety of problems or changes in circumstances and to approach the goals with flexible skills for handling these matters. In addition to these important criteria, perseverance when faced with difficulties and a “never-say-die” attitude will often result in success.

However, among all of the factors that contribute to success or failure, I think the most important criterion is personally having the passion to want to create a new product or to make it to the summit of a mountain.

Speaking from personal experiences, even if you fail in your attempts at product development or mountain climbing, if you put in as much effort as you can in the circumstances, the chances of tasting success the next time are very high. This is testimony to the fact that the only real way people have of learning is through their failures and that if we critically and objectively analyze our own experiences in failure and can take them on board, we have a much higher chance of success at our next attempt.

One of the goals we set ourselves for development of an electronic pipette was to stick to our own brand. About six years ago, we started selling devices for pipette quality and performance management. Since then, from our experiences in all the relevant stages – from planning through development to sales – of those products, we have been aware of the underlying problems of manual pipettes which currently dominate the market. Further, as a result of considerable market research before embarking on development, we also had a clear idea of what the problems were for existing electronic pipettes. From all these, we came to the conclusion that we had to develop a new type of electronic pipette which was highly unique and addressed all of the problems that could potentially occur in the actual places of use.

The newly developed electronic pipette was recognized as having high precision in multiple dispensing, being durable and hard to break, and being simple to operate with practically no risk of incurring repetitive strain injury. This led to it earning a reputation beyond even our own expectations. Once development of the unit itself was finished, the next problem we turned our minds to was the need to develop a convenient charging device which could keep the pipette in an upright position and allow simple charging in that state. All of the existing electronic pipette chargers were large standing types which allowed simultaneous charging of about four pipettes at a time.

Visiting a few laboratories for our own research, we found that existing chargers occupied a large space on the laboratory table, generally cost nearly as much as the pipettes themselves, and seemed to reduce the amount of freedom researchers had for installation. So with the assumption that researchers had a dearth of free space upon their laboratory tables, we set about developing a charging hanger which could be placed in any location they wanted. Our charging hanger was devised as having a similar form to manual pipette hangers, but with additional charging functionality. It should be a compact design which could be attached anywhere, such as the side of the laboratory table or to a medicine rack, etc., and also be capable of linking several units to the same power source for simultaneous charging. Keeping these specifications as our goals, we released a charger hanger for an electronic pipette onto the laboratory market with unprecedented ease of use, which could be freely placed anywhere at the user’s convenience, took up little space, and allowed use of multiple units at the same time.

I should share a few more details of our newly developed charging hanger. While offering a space where our MPA Series pipettes can be kept in a vertical position, the MPA pipette will start to be automatically recharged as soon as it is placed. Therefore when research work is wrapped up in the evening, by simply hanging the MPA pipette in its holder before returning home, the pipette will be fully recharged the next morning when you return to work, available for use straight away.

In general, one user uses more than one pipette, so we made it possible to recharge multiple MPA pipettes simultaneously by lining up multiple charging hangers. As it would be extremely cumbersome to have multiple units each connected separately to the AC power supply, once supplying power to one of those hanger units it can act as the “parent” hanger, with subsequent “child” units being connected to this first one by linking cables. It is also possible to confirm the hangers are receiving power by an LED light on the top of the hanger which illuminates when power is flowing. With this development it is possible to avoid the risk of all hangers going out of action if one of the consecutively wired hangers was to fail for some reason. A&D has applied for patents for these previously unavailable functionalities. By commercializing such products as this, we hope to continue pursuing and proposing convenience in laboratories around the world.

I believe that with the combined use of the MPA Series and their charging hangers we have established a simple method of use for pipetting work in the laboratory which is more accurate, places no strain on the user’s hands and offers a simple technique for recharging. From here on, I would like to continue growing this range of products even further with pipettes with increased capacity, multiple-channel types, connectable pipette stands and other further developments.

Discussion and Proposal on Management Methods for Micropipettes

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In the more than 100 years since Louis Pasteur’s breakthroughs establishing the field of microbiology, Western medicine has advanced remarkably to its present sophisticated levels. With its origins in the glass pipette, the micropipette, capable of measuring minute amounts of liquids to a high degree of precision, has been one of the essential tools in supporting these achievements, as a requisite piece of equipment in a biotechnology lab.

Presently, over 100,000 micropipettes are sold in Japan every year, and worldwide sales amount to over a million. Major pharmaceutical firms will often have several thousand micropipettes at just one of their main research laboratories. Micropipettes’ two most valuable characteristics are their ability to dispense tiny amounts of liquids, together with the easy handling provided by disposable pipette tips, which retain the sample being measured via air pressure, providing a reduction in occurrences of pipette contamination and also of the laborious process of cleaning pipettes. As a result, it could be said that micropipettes have made a significant contribution to improving the quality and productivity of testing and inspecting processes and are an indispensable tool in many aspects of biotechnology, pharmaceutical, foodstuff and clinical research.

While this convenience of use has meant the micropipette has come to be used in a wide variety of situations around the world, it would be hard to say there is a firmly established method for micropipette management. One of the reasons for this is the lack of an established method for managing its volumes as a quantity-measuring device. For example, while pipettes can determine volume, they are different from weighing machines in that they do not use weights or equivalent which can act as a reference standard for managing volume. This could be considered a very serious problem. Presently in pipette makers’ reports of results, volume (V) is determined from a calculation of V = m ÷ρ, where the coefficient of ρ is the density of purified water, which is a known quantity, and mass (m) is found by dispensing the purified water with a pipette on the tray of a balance and reading the displayed amount. However, the density of the water will change according to its temperature, so it is necessary to perform density correction at each different temperature. Another problem that could arise in practice is the pipette user dispensing a liquid other than water, with a different density. Further, the viscosity of water at 20°C of 1.002 mPa•s is extremely small and even a water solution with 50% glycerol will result in a viscosity level several times higher than purified water. Therefore, even if the pipette is calibrated with water, the density and viscosity of the liquid that is actually dispensed could differ from calibrated water and the interchangeability of the volumes will not be ensured, due to differences in the viscous resistance.

With micropipettes, the differences in air pressure created by the movement of the built-in piston are used for aspirating and dispensing of the liquid. Therefore, even with the same volume settings, differences in volumes will occur not only due to the viscosity and density of the liquid, but also the shape and material used for the tip. It is probably quite clear then, that with these conditions influencing measurement, dispensing volumes which differ from the pipette’s report of results is a quite a concern in many cases.

Besides such technical problems, there are also problems connected to the method of use of the pipette user. Namely, there are often individual differences in the manner of operation between users, as the pipette is held in the hand all day and it is also a very small tool to handle. Further, when the pipette is dropped from a desk or the hand, these kinds of impact loads can cause deformations in the operating rod or damage to the structure, which is associated with a reduction in precision in dispensed volumes.

With considerations such as these ones above, I started to have doubts about current pipette management techniques and thought about what kind of management methods should be used for pipettes under normal circumstances. For example, while you could say that having the pipette maker issue a calibration report once or twice a year is an important management technique, it is unrealistic to confidently assert that traceability or validation can be ensured in between periodic inspections that only occur once or twice a year. Further, even if calibration is performed with purified water and the tip specified by the manufacturer, there are other variations that can occur at the place of use other than the constitution of the liquid or the type of tip used, such as influences of the measurement environment or the degree of expertise of the user. I could only come to the conclusion that it is difficult to ensure traceability in the place of measurement with just the pipette maker’s report of results used for reference. Next, considering a solution to these problems, I was able to put my many years of experience in development of weighing devices to work by summarizing my proposed measures into the following two points:

1. As a precision weighing device manufacturer, we have a duty to provide to the market a management tool which can allow daily and periodic checks of pipettes at their place of use.

2. A new pipette is needed which allows pipette calibration management that reflects the actual conditions it is used under.

These two points above would be satisfied by providing, for example, devices that allow testing the pipette at the place of use when any kind of trouble eventuates, such as dropping it or aspirating too much liquid; a pipette equipped with a calibration function that applies the tip and liquid used, making it easy to perform calibration that actually fits the conditions at the place of use; and measures by which pipette maintenance can be performed easily by the user themselves.

As a result of the considerations mentioned above, in April this year A&D became the first manufacturer in Japan to release a general-use electronic pipette. Preceding this, we also developed a pipette leak tester and accuracy (volume) tester for pipette users five years ago. Using these management tools, it has become possible to create standard operating procedures (SOP) for pipette management to be carried out by users themselves. Further, we have also recently developed the AD-1695 dedicated pipette management tool which does not require the use of a PC. As the AD-1695 allows interactive operation with its graphic user interface, daily and periodic checks of the pipette can be performed with ease at user level.

Our newly released original electronic pipette is equipped with calibration functionality in µl units and allows volume calibration by users themselves. For calibration in µl units with liquids other than water, difficult density measurement of the liquid is required. To help with this, we have also added a new calibration and display function with mg values. By performing measurement and calibration of volume with mg units, measurement and correction of density is no longer required and pipette calibration can then be performed using the mg value displayed by the balance. Having a uniform unit of mg for measurement and calibration means calibration with the liquid and tip to be actually used becomes much easier to perform, and means that a mixture consisting of a measured amount of powder and liquid can be simply and accurately calculated by weight ratio.

With the MPA series of electronic pipettes, the lower part of the device including the piston, which is often subject to contamination, and the main part of the pipette (control and drive parts) are designed as separate units, so can be easily detached from each other. Therefore, sterilization using an autoclave is now possible for the lower part only, and due to the design of the MPA series this part can also be simply disposed of and replaced by anyone when contamination or wear occurs.

As a result of our considerations over the last five years, I think that we have finally achieved a range of nearly ideal micropipettes and accompanying management tools that offer practical solutions for the actual conditions that are encountered in everyday pipette use. I hope that these devices can be used both as an aid to creating SOPs for those responsible for pipette management and also as effective tools for ensuring safe and reassuring use for pipette users. A&D has already prepared original guidelines and documents on these subjects that enable simple creation of SOPs for pipette management. Please feel free to contact us at any time to discuss any matters relating to our pipettes and pipette management tools.

Functionality and Performance of Electronic Pipettes

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In spring this year, A&D launched our new MPA Series of original electronic single channel pipettes. With our exciting new products in hand, we visited research laboratories across Japan to explain their many benefits, starting in Kyushu’s Fukuoka, then moving to Shikoku Island, Osaka, Kyoto, Nagoya, the Hokuriku region, then finally areas in around Tokyo. Our promotional activities have already extended overseas as well, introducing the MPA Series to laboratories in Korea and conducting some market research there.

In this Development Story, I will summarize what we have learned from this market research and propose practical solutions to some of the problems that pipette users are facing in their place of work.

  • Dispensing liquids with a high level of viscosity

If the viscosity of the dispensed liquid is high, it sticks to the outer perimeter and inner surface of the tip. Liquids that particularly pose a problem are those that stick to the inner wall of the tip. When this happens it is not possible to cleanly discharge or ensure accurate dispensing amounts. Addressing this problem requires, 1) slowing down the aspirating and dispensing speeds so the liquid can be properly transferred; 2) aspirating a larger amount of the liquid beforehand and establishing the dispensed amount based on the amount discharged (this is commonly called reverse mode and reduces the degree of error with the liquid that remains inside the tip); 3) using a tip with a wide circumference to reduce the pressure added to the high viscosity liquid. MPA electronic pipettes have five different speeds of aspiration and dispensing selectable and can be easily set to reverse mode, making more stable dispensing possible.

However, whichever of these methods is used, dispensing liquids with viscosities around 10 times higher than water (10 mPa•s) will always be a problem for micropipettes which rely on air pressure for their operation. A type of dispensing device that has a piston attach the liquid would have to be used for any viscosity level higher than this.

  • Dispensing highly volatile liquids such as solvents

Many researchers feel that the dispensing of highly volatile and low viscosity liquids such as solvents is rather difficult. The cause of this problem is the empty space in the cylinder built into the pipette becoming filled with vapour from the solvent or other volatile liquid. In other words, as soon as the solvent is aspirated the piston is filled with vapour from the solvent, which increases pressure inside the cylinder and forces the solvent to leak out of the tip or makes the dispensing amount inconsistent. In order to avoid this phenomenon, it is recommended to aspirate and discharge the solvent several times before the dispensing is performed to create a constant vapour pressure. This so-called “pre-rinse” practice is recommended for not only solvents, but as an effective general preparation measure to ensure the accuracy of the dispensing process. One of the MPA Series’ many merits is simple switch-only operation of multiple aspiration-discharge actions which are effective for mixing liquids or performing pre-rinse.

  • Operability when performing consecutive dispensing

Dispensing to a 96-well microplate is a difficult operation and even if a multiple channel pipette is used, a high degree of skill and dexterity is required to ensure correct dispensing amounts. When a manual single channel pipette is used for repeated dispensing, the same parallel movement of aspirating and dispensing is needed to be done many times, a frustrating task for the researcher and one which can consume a significant amount of time. With an electronic single channel pipette however, with one touch of the switch an amount equivalent to fill 8 or 12 wells can be aspirated in one go, then evenly dispensed with 8 or 12 touches. Particularly when very precise dispensing is required or when there is a need to reduce wasted use of an expensive solution, using an electronic single channel pipette, which provides easy operation and high accuracy, is shown to be the most effective measure.

  • Consecutive dispensing with an electronic pipette

When multiple dispensing is performed with an electronic pipette, even amounts cannot be ensured and the first time can be a touch short. We also regularly hear that the final dispensed amount can also be insufficient among other complaints. These issues can also occur with manual-type pipettes in principle, however as multiple dispensing cannot be performed with manual pipettes each dispensed amount cannot truly be compared with others and is therefore not acknowledged as a problem.

The cause of this error in multiple dispensing could be explained as a phenomenon generally called “backlash”. Simply put, this is the same as backlash in the steering wheel of a vehicle. Backlash occurs in the steering wheel of a vehicle when it stops moving in one direction and then starts moving in another, with a delayed response due to gaps between the gears or screws. For pipettes, backlash is caused by the looseness of the screw that controls the variable volume as well as slight shifts in position of parts, such as the o-ring for sealing the cylinder, due to variances in pressure between the negative pressure when aspirating and the application of pressure when dispensing, resulting in changes in volume.

From the explanation above, it can be understood that backlash occurs in both manual and electronic pipettes. For manual pipettes, this occurrence of backlash cannot be resolved. However, for electronic pipettes, it can be avoided. This is because the dispensing amount can be stabilized by aspirating more liquid than is required and before dispensing the liquid automatically discharging a minute amount. In the MPA series, we call this function “pre-dispense” and it comes as standard on all models. We are currently applying for patents and trademarks for this function, but meanwhile, with the addition of this function to the MPA Series, the problem of measurement error in the first dispense of multiple dispensing operations typically seen in previous electronic pipettes has been successfully minimized.

With use of this “pre-dispense” function, we have achieved an enormous improvement in dispensing performance, halving the degree of repeatability compared to manual pipettes manufactured by major pipette makers. I’m intending to report concrete details on this in an academic conference in 2014.

  • Compatibility between pipettes and tips

Visiting several research laboratories, we were asked every time about compatibility with tips that are already being used. We insisted that the MPA Series is compatible with existing tips, but the researchers we spoke to were not interested in general terms, but rather in the compatibility with the very tip that they were presently using in their own laboratory. We therefore saw the need to try fitting the MPA Series with most of the tips presently available in the market and check if they deliver accurate dispensing without any leaks. The results are published on our website. From the results of our tests we can say that, with the exception of special tips developed for use only with certain devices, any tip can be used with the MPA Series. However, in tip types with a long overall length, a slight loss in the dispensing amount was noticed. Nevertheless, even in cases such as this, one of the advantages of the MPA series being electronic pipettes is that digital calibration can be easily performed by the user in microliters, or in milligrams like balances. As they can be calibrated at their place of use, the accuracy of the MPA Series can be guaranteed and they can be used with complete peace of mind. (An application for a patent for the digital calibration function of the MPA Series has also been lodged)

  • Breakdown and maintenance

It is generally known that a pipette is a device that will break if it is dropped. For manual pipettes, the push-down axle bending or the base part of the tip holder breaking are commonly reported breaks. There are also problems associated with the user aspirating too much of the liquid leading to rust or corrosion of the piston. With electronic pipettes, there have been many reported cases of the display or even the entire device not working after a fall, which has hindered any increase in sales of these devices. In order to protect what could be called the weak spot on an electronic pipette – the display section at the top – the MPA Series features specialized protectors on each four corners of the head section. The design of these patent-pending protectors realizes highly effective durability for the MPA Series, achieving shock resistance from a 1 meter drop when tested dropping the MPA Series onto a P-tile on a concrete base from that height. There is also no chance of over-aspirations from operation errors, as all aspirations are automatic.

The maintenance of the MPA Series is limited to the so-called lower part of the device, which includes the tip holder and piston. This part can be easily removed and replaced by the user themselves, with the pipette ready to be used once again straight away after calibration has been performed.

  • Pipette management methods

How should pipettes be properly managed in their place of use? We were asked this question on many occasions. Pipettes should be managed in their place of use in accordance with the procedures stated in the document called Standard Operating Procedures (SOP). Broadly speaking, these procedures could be divided into “daily check” and “periodic inspection”, which could be compared to daily checks of a car and official vehicle inspection. Daily check of the pipette includes confirmation that the exterior is undamaged, that there are no problems with its functions like switches, etc., that there are no leaks in the piston area and so forth. Periodic inspection encompasses all the items of a daily check as well as an examination of the performance of the device, which requires validation of amounts measured by the device by either volume or mass. It will be necessary to decide in advance what to do with a faulty device if any problems are detected during these checks and examinations.

As we considered management methods for pipettes at their place of use would be essential in many cases after we sold the MPA Series, we produced a document that acts as a guide to create Standard Operating Procedures. When introducing this document to researchers responsible for management of equipment such as pipettes, we have been receiving extremely positive responses.

Micropipettes are exempted from Good Manufacturing Practices (GMP), with the assumption that they are not used on the manufacturing floor. However, they are in fact vital in such places for quality management, not to mention for research and clinical examinations. We believe that in the future it will be hard to tell the difference between skilled hands and beginners when using these electronic pipettes, with improvements in repeatability even for the former group, and the rate of use of these easy-to-use devices will increase significantly.

A&D, as a manufacturer of measurement instruments, has a background of being the first company to develop and commercialise pipette management tools. And finally, using our know how in the field, we have developed our own unique MPA Series of micropipettes. We are anticipating this MPA Series to achieve significant gains in quality, as well as reductions in the burden of repetitive pipetting work, in research laboratories and clinical trials around the world with its durability, ease of use, and exceptional performance.