Description: Biological and chemical hazards threaten human health and are of growing world concern. Wearable sensors offer the potential to monitor local exposure of individual users while enabling distribution across a global scale. Electrochemical sensors have many characteristics that meet the challenging performance requirements of wearable sensors. However, the electrochemical instrumentation circuits are too heavy, bulky, expensive and consume too much power for wearable applications. This project investigates CMOS circuit design for wearable electrochemical sensor arrays in health hazard monitoring. In Gen. 0 system, microcontroller board and environmental sensors are integrated for initial evaluation of system concept. In the Gen. 1 system, a unique multi-mode resource-sharing instrumentation circuit was developed to integrate amperometric and impedance sensing abilities, and share electronics components among recording channels, with reduced size, cost, and power. In the Gen. 2 system, a new CMOS amperometric circuit that combines digital modulation of input currents and a semi-synchronous incremental Σ∆ ADC was developed. The circuit simultaneously achieves a combination of wide dynamic range (164 dB), high sensitivity (100 fA), high power efficiency (241 µW) and compact size (50 readout channels on a 3×3 mm2 chip) that is not available in any existing instrumentation circuits.
Investigators: Haitao Li