GaN-based micro chemical sensor nodes for early warning chemical agents

We are developing micro chemical sensor nodes that can be used for real time, remote detection and early warning of chemical agent threats. The chemical sensors in our sensor nodes utilize GaN HEMTs (High Electron Mobility Transistors) fabricated with catalytically active transition metal gate electrodes. The GaN HEMT chemical sensors exhibit high sensitivity and selectivity toward chemical agent simulants such as DECNP (Diethyl cyano phosphonate), and this is the first time that chemical agent simulants have been detected with GaN micro sensors. Response time of the GaN HEMT sensor to a chemical species is within a second, and the maximum electronic response speed of the sensor is ~3 GHz. A prototype micro chemical sensor node has been constructed with the GaN sensor, a micro controller, and an RF link. The RF sensor node is operated with a single 3V Li battery, dissipating 15 mW during the RF transmission with 5 dBm output power. The microcontroller allows the operation of the RF sensor nodes with a duty cycle down to 1 %, extending lifetime of the RF sensor nodes over 47 days. Designed to transmit RF signals only at the exposures to chemical agents and produce collective responses to a chemical agent via a sensorweb, the GaN micro chemical sensor nodes seem to be promising for chemical agent beacons.