Microsystem-Compatible Heterogeneous Micro-Hydrophone for Use at High Static Pressure

Abstract:

Underwater acoustic sensing is important for multiple applications, including seismic sensing for the oil and gas industry, SONAR at extended ocean depth, localization, implementation in autonomous microsystems, and marine mammal research to name a few; however, there is a lack of hydrophones that can operate at ambient pressures in the range of 5-50 MPa while still offering a miniature form factor, compatibility with lithographic manufacturing methods, and compatibility with autonomous microsystems. A new micromachining process has recently emerged that shows promise in addressing these concerns.  The thin-film MEMS process uses surface micromachining technology to create hermetically vacuum sealed, variable gap capacitive sensing elements with touch mode capability that virtually eliminates pressure overloading. Heterogeneous architecture enables competitive sensitivity, bandwidth well into the MHz region, operation over 50 MPa static pressure, static pressure response, and sensor volume of 1.1 mm³. This work investigates the ability for the micromachining process to produce a hydrophone and demonstrates the hydrophone’s use in several applications of interest.

Chair: Professor Yogesh Gianchandani