Noise Squeezing Controlled Parametric Bifurcation Tracking of MIP-Coated Microbeam MEMS Sensor for TNT Explosive Gas Sensing

• Published in: Journal of microelectromechanical systems Vol. 23; no. 5; pp. 1228 - 1236
• Main Authors: Li, Lily L., Holthoff, Ellen L., Shaw, Lucas A., Burgner, Christopher B., Turner, Kimberly L.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.10.2014; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Bifurcation; Bifurcations; Compressing; Confidence intervals; Detection; Explosions; Field programmable gate arrays; Frequency control; Gas sensors; mass sensing; Microbeams; Micromechanical devices; Noise; noise squeezing; Phase noise; Sensors; Tracking; Bifurcation; mass sensing; noise squeezing
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/JMEMS.2014.2310206

This paper reports real-time explosive gas sensing (DNT) in atmospheric pressure utilizing the noise squeezing effect that occurs before a bifurcation event. A noise-squeezing controller based on the statistics of phase noise is implemented using high-speed LabVIEW field programmable gated array. 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 show 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.