Continuous Monitoring of TATP Using Ultrasensitive, Low-Power Sensors

There is a growing need for a continuous monitoring system that can detect explosives such as triacetone triperoxide (TATP) in the vapor phase at trace levels. TATP is an energetic material commonly used by terrorists in improvised explosive devices both as the initiator and the energetic material itself. TATP is still going largely undetected in many densely populated venues such as train stations and airports. No electronic trace detection system currently exists that is capable of continuously monitoring TATP, or its precursors, in the vapor phase. Recently, we developed a thermodynamic sensor that can detect TATP and other nitrogen-based explosives in the vapor phase at the ppb level. These ultrathin sensors showed unparalleled sensitivity and could even be operated at low enough powers to enable them to be deployed on drones. The sensor relies on specific oxidation-reduction reactions between the energetic molecules and metal oxide catalysts. Here, catalyst coated microheaters measure the heat effects associated with redox reactions occurring on the surface of the metal oxide catalyst. Enhanced sensitivity and selectivity were achieved through implementation of ultrathin ($8~\mu \text{m}$ thick) yttria-stabilized-zirconia (YSZ) as the substrate for the sensor platform. This reduction in the thermal mass combined with the catalytic amplification associated with Pd microheaters and optimized catalyst porosity enabled us to detect TATP in the vapor phase at unprecedented levels.