Development of a MEMS-Scale Photoacoustic Chemical Sensor Using a Quantum Cascade Laser

The development of a microelectromechanical systems-scale photoacoustic chemical sensor is described. Specifically, both a pulsed and a modulated continuous wave quantum cascade laser were used to determine detection limits for dimethyl methylphosphonate (DMMP), a standard nerve gas simulant. These sources were continuously tunable from 9.3 to 10 ¿m. We report a minimum detection level of 20 parts-per-billion (ppb) and exceptional agreement between the measured photoacoustic vibrational spectrum and the IR spectrum of DMMP. The results support the continued development of a miniaturized photoacoustic sensor.