Self-tuning porous silicon chemitransistor gas sensors

This work breaks a new ground in the gas sensor arena by demonstrating that concepts of self-repairing (self-tuning) materials and electronics can be successfully applied to sensor design, thus envisaging a novel class of self-tuning gas sensors with increased lifetime, enhanced reliability, and improved environmental sustainability. In this work, electrical tuning of the sensitivity of nanostructured chemistransistor sensors, specifically porous silicon (PS) junction field-effect transistor (JFET) gas sensors (PSJFETs), by bias-control of the gate-terminal is shown to effectively address two chief problems of solid-state gas sensors, namely fabrication reliability and aging effects, which represent a major bottleneck towards in-field applications. Proof of concept is given, both theoretically and experimentally, by fully compensating the effect of fabrication errors on the sensitivity of two PSJFETs integrated on the same chip, which, though identical in principle, feature different sensitivities (about 30%) to NO₂ before compensation. Although fabrication tolerance compensation of chemitransistor sensors by sensitivity tuning is here demonstrated for the specific case of the PSJFET, the general concept can be in principle applied to other chemitransistor sensors that exploit nanostructured sensing materials different from porous silicon.