One-channel time reversal focusing of ultra-high frequency acoustic waves on a MEMS

• Published in: Applied physics letters Vol. 122; no. 10
• Main Authors: Dahmani, H., Smagin, N., Campistron, P., Carlier, J., Toubal, M., Nongaillard, B.
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 06-03-2023
• Subjects: Acoustic waves; Acoustics; Applied physics; Engineering Sciences; Micro and nanotechnologies; Microelectronics; Microfluidics; Micromachining; Silicon; Sound fields; Transducers; Ultrahigh frequencies; Zinc oxide; Transducers; Kaleidoscopes; Time domain approach; Elastic energy; Ultrasonography; Signal processing; Micro-machining; Acoustic field; Ultrasound; Microfluidics
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/5.0142179

This Letter reports on a work performed to fabricate and characterize a silicon micro-machined cavity dedicated to micro-resolution Ultra-High Frequency imaging in microfluidics and microbiological applications using one-channel time reversal. Time reversal provides the means to spatially and temporally localize elastic energy on a receiver. Here, the arrays of zinc oxide micro transducers are coupled with a 400 μm thick silicon wafer containing micromachined structures for acoustical field confinement. Characterization of the diffused acoustic field and time-reversal retro-focusing are reported. The transducers are wideband in the 0.2–2 GHz range with a central frequency of 0.9 GHz.