Non-glass, unbreakable advanced ISFET pH-sensors


Can the reference electrode R2K712 be used with Shindengen Electric Mfg. IQ120 and IQ125?
Our reference electrode R2K712 is compatible with CH701 and CH723 manufactured by Shindengen Electric Mfg. Ltd. There are various problems with the KS 701 and KS723 models such as a very small sample can not be measured and dirt contamination becoming lodged in the space between the semiconductor sensor and reference electrode. We were able to solve these problems and achieved measurable performance improvement. Using our R2K712 reference electrode in the KS701 and KS723 will achieve the most accurate pH measurement. Please try it at your convenience.The replaceable reference electrode R2K712 is new model which is possible to make one-drop measurement without any contamination and improve the pH-responses of ISFET-pH meters. The R2K712 is compatible with the MiniLab pH meters of IQ120, IQ125 and IQ128 only.


It is said that the pH of even one drop can be measured, but quantitatively how much sample is required?
The S2K series pH meters are the first meters in the world that can measure the pH of a one drop sample. The sample volume of sample required is only 0.05ml. Provided the pH sensor and the white dot on comparison electrode can be covered with a drop, the pH can be measured.
In the foods testing industry there are “needle type” pH electrodes that can be be used to penetrate meets and fruits to measure the pH. Can the S2K712 be use in such applications?
This type of use cannot be done with the S2K series pH meters. Although using an ISFET sensor achieves a stable pH sensor, according to the view point of the Hazard Analysis and Critical Control Point (HACCP) of Food Sanitation, the intricate structure of the sensor probe introduces the possibility of transferring bacteria from sample to sample.
However, measuring the pH of a small sample of the foods taken from the processing line is possible.
How can I get the temperature of the sample solution to display?
This pH meter alternately measures and displays the pH value and the temperature in real time. There may be two cases where action must be taken to see the temperature. 1. The pH reading does not stabilize; 2. There are two kinds (of what). In these cases, push the POWER button, to turn off the meter, so that the pH measurements may learn the temperature of the sample solution. A temperature and pH values are alternately displayed immediately after turning on the meter.
In concrete terms how should the pH sensor be cleaned?
When the pH sensor becomes dirty, please clean it using detergent and a soft toothbrush with extra fine fibers. Please rinse the tip in tap water, scrub with detergent, rinse and dry with clean tissue paper.
What is the difference between the ISFET pH meter and the glass electrode type pH meter?
The S2K series of pH meters use a silicon semiconductor called ISFET as a pH sensor. ISFET is an acronym for Ion-Sensitive Field-Effect Transistor . Because the potential on solution/gate film field changes according to the pH of a solution, when the solution touches the gate insulation film of ISFET sensor, it senses the pH of the solution. ISFET was developed by making use of the latest microelectronics and provides an alternative to the glass electrodes that cracked easily. ISFET pH meters are the only meters that can measure the pH of a samples as small as one drop. Moreover, the semiconductor technology allows quick temperature measurement by integrating a temperature sensor, and is offering a pH meter that is more convenient than glass electrode type pH meters. Everyone should be encouraged to try this pH meter that is accurate, portable, and can be used anywhere with ease.
Does this pH meter become unusable if it not used for a long period and the sensor dries out, as is the case with glass electrode type pH meters?
Glass electrode type pH meters become unusable if the glass electrode sensor dries out. Users are strictly prohibited from allowing glass pH sensors to dry out, but the S2K712 and S2K922 is easily operated and can be used again and again without the concern about the sensor becoming dry between uses.
The S2K712 and S2K922 have an efficient insulation film that protects the surface and means the devise is not compromised by drying out. By simply washing the pH sensor with a weak detergent and rinsing after each use, and changing the R2K712 reference electrode and batteries as needed, the S2K series pH meters can be used for many years.
Moreover, if you are having difficulty with an ISFET pH meter made by the OEM company Shindengen Electric Manufacturing Co., please contact us and try our R2K712 reference electrode. It will improve the performance of your pH meter.
Can the temperature of the measurement solution measure the pH and the temperature at even 50℃ or more?
Measuring the pH of samples >50℃ is possible, although the longevity of the pH meter will be compromised because it is possible the plastic parts of meter may deteriorate at these higher temperatures. An alarm display 【H.L℃】 is displayed with the pH value and the temperature when measuring high temperature samples.
Can the pH a sample of a strong alkaline, or of a strong acid, out side the pH2 ~ pH12 range be measured?
The measurement is possible though not recommended because the plastic parts may deteriorate when exposed to samples outside the pH2~pH 12 range. An alarm display 【H.LpH】 is displayed with the pH value and the temperature while measuring a sample outside this range.
How can the we measure the pH of potting soil from household plants.
There are in detailed methods for measuring the pH of soil available from government agencies, we will give a simple explanation here. Using a clean PET bottle or glass beaker, mix purified water with the soil sample thoroughly, and then measure the pH of the water from the surface.
What should be done when the malfunction Error Code [Er3pU] blinks and the pH meter does not operate?
This indicates a breakdown of the electrical circuits and the pH sensor in the pH meter. Please contact the distributor. (Please note that dismantling the pH meter may void the warrantee.)
What should be done when the malfunction Error Code 【Er3℃】 blinks and the pH meter does not operate?
This indicates a breakdown of the temperature sensor. Please contact the distributor. (Please note that dismantling the pH meter may void the warrantee.)
We purchased a MiniLab series IQ120 made by the IQ company and we obtain measurments but the results are unstable reproducibility.
The below is a graph of repeated pH measurements of the same liquid from both the “Hach Company’s copy pH meter IQ120” and “KS701 (S2K712) made by Shindengen Electric Mfg in an indoor environment.
faq13-1faq13-2Results from the Hach Company’s pH meter (IQ120) are unstable to the point that readings that are of little practical use. On the other hand, the results from the KS701 (S2K712) made by Shindengen Electric Mfg., shows stable reproducible pH readings.
In both pH meters (accurate to ±0.1 pHs (S2K712) or ±0.05-pH (S2K922) a one-point calibration is recommended. Although a two point calibration function is available, it is not recommended. Why is a 2-pt calibration not recommended?
The pH response sensitivity of the S2K series pH meters changes very little because the pH sensitivity in ISFET (Ion- Sensitive Field-Effect Transistor) type pH meters is based on a mechanism of a change in potential on the solution gate film depending on the pH of the solution applied.
The sensitivity of the ISFET pH sensors only changes when the thin film covering the semiconductor is damaged or dirt adheres to the induction film. In such cases, there will be a dramatic change in sensitivity. There is no deterioration of sensitivity even if it dries out or is not used for a long period of time.
On the other hand, in glass electrode pH meters the membrane on the glass thins and deteriorates over time, causing a change in pH sensitivity. This is one reason that when using glass electrode type pH meters, two-point calibrations are necessary. As a result, in many countries around the world, two-point calibrations are required by industry standards.
In an ideal world, pH meters would require no calibration. So some users may be frustrated with the two-point calibrations that add expense and consume precious time. But because of the delicate nature of their components, it is an inevitable task when using glass electrode pH meters.
On the other hand, the change in pH sensitivity is extremely small with our S2K series pH meters. Because the pH sensitivity is set in our factory and does not fluctuate, troublesome two-point calibrations are not needed with our pH meters. Since there is no significant deterioration in sensitivity, our company takes the position that it is not necessary to comply with industrial guidelines designed to insure accuracy and stability of sensitivity of delicate glass electrode type pH meters. Needless to say, the above applies ONLY to ISFETCOM, Co., Ltd. pH meters, not to ISFET type pH meters made by other manufacturers.

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