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Chemosensors 2018, 6(1), 6; https://doi.org/10.3390/chemosensors6010006

Stand-Off Chemical Detection Using Photoacoustic Sensing Techniques—From Single Element to Phase Array

1
Computer Science and Electrical Engineering, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21227, USA
2
NeoPhotonics Corporation, 2911 Zanker Road, San Jose, CA 95134, USA
3
Brimrose Corporation, 19, Loveton Circle Sparks, MD 21152, USA
*
Author to whom correspondence should be addressed.
Received: 19 November 2017 / Revised: 18 January 2018 / Accepted: 19 January 2018 / Published: 23 January 2018
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Abstract

Technologies that can detect harmful chemicals, such as explosive devices, harmful gas leaks, airborne chemicals or/and biological agents, are heavily invested in by the government to prevent any possible catastrophic consequences. Some key features of such technology are, but not limited to, effective signal-to-noise ratio (SNR) of the detected signal and extended distance between the detector and target. In this work, we describe the development of photoacoustic sensing techniques from simple to more complex systems. These techniques include passive and active noise filters, parabolic sound reflectors, a lock-in amplifier, and beam-forming with an array of microphones; using these techniques, we increased detection distance from a few cm in an indoor setting to over 41 feet in an outdoor setting. We also establish a theoretical mathematical model that explains the underlying principle of how SNR can be improved with an increasing number of microphone elements in the phase array. We validate this model with computational simulations as well as experimental results. View Full-Text
Keywords: photoacoustic; sensing; quantum cascade laser; chemical detection; acoustic beam-forming; acoustic phase array photoacoustic; sensing; quantum cascade laser; chemical detection; acoustic beam-forming; acoustic phase array
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).
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Gupta, D.; Chen, X.; Wang, C.-C.; Trivedi, S.; Choa, F.-S. Stand-Off Chemical Detection Using Photoacoustic Sensing Techniques—From Single Element to Phase Array. Chemosensors 2018, 6, 6.

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