Instrumentation system to improve ISFET behaviour

Solid state chemical sensors have many advantages over conventional glass electrodes, such as smaller size, faster response and lower cost. Nevertheless, the limitations imposed by their temporary drifts, thermal dependencies and hysteresis must be considered in these sensors´ performance. These limitations are not so important in applications that do not require high precision. But in the case of biomedical applications they cannot be ignored. We introduce a new electronic conditioning circuit plus a virtual instrumentation that cancels or reduces these limitations. As result of the study, we can conclude that the new measurement method allows a 0.06 pH precision. The conditioning circuit maintains stable sensor feedback in an automatic way, independent of its temporary drifts and thermal dependencies.