MEMS Cantilever Sensor for Photoacoustic Detection of Terahertz Radiation

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MEMS and Nanotechnology

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Cantilever structures have long been used in a variety of sensor and actuator applications. In this work, a Microelectromechanical system (MEMS) cantilever pressure sensor was designed, modelled, and fabricated to investigate the photoacoustic response of various gases to terahertz radiation. Cantilever design parameters of length, width, and thickness are investigated using CoventorWare finite element model software. Cantilever tip deflection and resonant frequencies of the beams are of particular interest in order to maximize the effectiveness of the sensor. A few select designs were then fabricated on the device layer of a silicon-on-insulator wafer which was used to create the physical structure of the cantilever. Fabricated devices will then be tested in a custom made vacuum test chamber where the amplitude modulated THz radiation excited acoustic waves in the chamber and cause the cantilever to deflect. To examine the induced deflection in the cantilever, a laser beam reflected off the tip of the cantilever back to a photodiode to analyze tip displacements caused from the photoacoustic effect. Initial test measurements are currently underway and initial data indicates a nearly linear response in signal amplitude from the photodiode which directly correlated to the gases absorption coefficients.


MEMS and Nanotechnology, Conference Proceedings of the Society for Experimental Mechanics Series, Vol. 5 (2013): 73-79. DOI.

Ronald A. Coutu was affiliated with Air Force Institute of Technology at the time of publication.