The Implementation of a High-Performance Glucose Biosensor Based on Differential EGFET and Chopper Amplifier

In this paper, a new architecture for glucose biosensors is proposed, which adopts a Chopper amplifier instead of a conventional instrumentation amplifier (INA) and differential extended gate field effect transistor (EGFET) as the input stage. The architecture effectively suppresses low-frequency noises such as flicker noise and significantly improves signal quality while reducing power consumption and layout area. The simulation results indicate that when the chopper frequency is set to 5 kHz, the chopper amplifier effectively reduces the output-referred noise at 1 Hz from 20.01 $\mu$ V/ $\surd$ Hz to 394 nV/ $\surd$ Hz. In the experimental part, we fabricated a glucose biosensor containing a RuO2 sensing film, and analyzed the surface morphology of the sensor's working electrode by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The experimental results showed that the biosensor exhibited good linearity (0.998) and sensitivity (82.83 mV/mM) over the glucose concentration range of 3 mM to 7 mM. In addition, the modulation and demodulation capabilities of the Chopper amplifier were verified through Hspice simulations and real-world tests, and it was confirmed to be effective in reducing noise.