Electronic interface modules for solid-state chemical sensors

Plug and play modules for interfacing three common types of solid-state chemical sensors are presented The self-contained (integrated circuit) modules detect a baseline signal from a sensor and auto-zero the signal to compensate for baseline variations, both immediately after fabrication and periodically during the lifetime of the sensor The signal compensation technique is based on the governing transduction principles of the chemical sensor thereby enabling signals to be compensated without distortion. After fabrication, sensors are auto-zeroed at their field operating conditions to ensure that all homogenous sensors begin at the same baseline output. Re-zeroing is completed at a time scale compatible with the drift and lifetime of the sensor and is automated in similar manner to the initial autozeroing step that occurs during calibration. The matching of automated baseline compensation to governing transduction principles for chemical sensors is a novel effort. This paper will present experimental results at the circuit, architecture and system level using chemFETs, composite film polymer chemiresistors and tin-oxide chemiresistors.