EG-ISFET Interface with ADC Conversion and Programmable Calibration

Currently the integration of sensors with a readout circuit and display are implemented in embedded systems for industrial, medical, chemical, and agricultural applications. This study presents the development of the conversion stage from analogical to digital, the calibration and the signal conditioning for an extended gate ion sensitive field-effect-transistor (EG-ISFET), based on an eight-bit microcontroller which offers a fast and reliable answer, the system shows the result of the ionic concentration of hydrogen (pH) of an electrolyte with a 3-display arrangement. The embedded system uses a calibration algorithm based on functions of mathematical correction beginning with the calculation of calibration coefficients and also shows a pH measurement in the range of 4 to 9, with a resolution of 51.6 mV/pH.