A Handheld Biosensor Platform for Disposable ISFET-Based Sensor

Abstract

This thesis presents a compact handheld biosensor platform for ISFET-based sensors. To implement completely portable and stand-alone biosensor platform for wearable and IoT devices, user interfaces and power management circuit including battery are embedded. The biosensor is mounted on a disposable printed circuit board cartridge and can be easily replaced with others by a connector. This thesis presents two methods for biosensors at the system level: a method to safely drive the vulnerable biosensors and a method to avoid irregular threshold voltage shifts. The biosensor platform can perform linear sweep voltammetry and measure the threshold voltage shifts. In accuracy test with resistor, the platform achieves less than 14-nA current error within the measurable current range of 12 μA. The pH responses were tested with different pH buffer solutions. The biosensor platform achieved a high sensitivity of 39.3 mV/pH. This biosensor platform will be applicable to other biomolecules as well as to pH sensing.