Phase noise squeezing based parametric bifurcation tracking of mip-coated microbeam mems sensor for tnt explosive gas sensing

Abstract

This paper reports real time explosive gas sensing (DNT) in atmospheric pressure utilizing the noise squeezing effect that occurs prior to a bifurcation event. A noise-squeezing controller based on the statistics of phase noise is implemented using high speed LabVIEW™ field programmable gated array (FPGA). A high frequency TNT-molecularly imprinted fixed-fixed microbeam sensor utilizes this nontraditional sensing strategy and performs DNT sensing at various concentrations. Experiments are conducted using both noise-based and sweep-based bifurcation tracking for a direct comparison. Results demonstrate noise-based bifurcation tracking is not only capable of performing reliable frequency tracking, but also shows the method is superior to the bifurcation sweep-based tracking. Over three orders of magnitude improvement in acquisition rate is achieved, and, as a result, confidence and precision on bifurcation frequency estimation is significantly improved over the bifurcation sweep tracking method, enabling DNT sensing at concentrations much below sub-ppb (parts-per billion) level.