Low-power embedded readout and processing system for ISFET sensors as measurement devices

Abstract

Ion Sensitive Field Effect Transistors (ISFETs) have been widely used in different applications because of its rapid response and robustness. There are many structures of conditioning circuits proposed for ISFETs oriented to specific applications and a integrated solutions. This paper, proposes a completely embedded readout circuit and processing system to employ them as part of pH monitoring systems. The implementation was performed in the mixed signal microcontroller PSoC 5LP, with a classical constant-current and constant-voltage structure (CVCC) of 25μΑ and 300mV. Results shows a sensibility of 51mV/pH at 25°C and a compensated output with +/− 0.02pH of tolerance and 0.02 of resolution.