Unbreakable and Unshakeable Do ISFET pH electrodes live up to the hype?
The importance of maintaining proper pH levels during food production should never be underestimated. With yogurt, incorrect pH levels can lead to discoloration, excessive free whey, and additional or insufficient tartness. In the production of wine it can lead to biological and chemical instability, damaging the looks and taste of the beverage. So it only makes sense that when monitoring pH you rely on the most advanced sensor technology availablein this case, an ion sensitive field effect transistor (ISFET) electrode. For most food & beverage and pharmaceutical applications, in which the use of glass electrodes on the production floor is prohibited, ISFET electrodes are ideal. The body of the electrode is typically made of stainless steel or PEI, and there is no glass in the sensor tip. Instead, ISFET electrodes rely on a silicone chip which, when placed in contact with the sample, detects and measures the variable voltage potential between its surface and underlying semiconductor material. This variable potential is proportional to the hydrogen ion concentration in the sample, and is thus used to precisely derive the pH value. Above all, ISFET electrodes are durable and easy to maintain. The sensing surface of the probe is made of such hard materials as aluminum oxide, which is used as an abrasive in some sandpapers. These materials are non-porous, and allow the unit to be thoroughly cleaned with only soap, water and a toothbrush without fear of sensor degradation. And unlike glass electrodes, which degrade even during storage, ISFET probes have an indefinite shelf life and can be stored dry. In fact it is not unusual to use an ISFET electrode for three to four years under normal laboratory conditions. If there is a drawback to ISFET technology, it is that previously ISFET electrodes could only be used with specifically matched pH meters. Recently, however, OAKTON® introduced the extremely versatile FlexipHet ISFET electrode which offers all the benefits of the technology, and it will work with any pH meter with a BNC connector. ISFET Technology Laboratory Electrodes pH Electrode Theory |
