Realization of a composite MEMS hydrophone without left-right ambiguity

A sound-pressure sound-pressure-gradient composite MEMS vector hydrophone has been proposed and demonstrated to solve the problem of left-right ambiguity that is intrinsic to existing MEMS hydrophones measuring the pressure gradient of a vector sound field. A newly-designed capacitance scalar microstructure is added into a MEMS vector hydrophone that otherwise consists of only a regular cilium-four-beam microstructure. Theoretical model shows that the left-right ambiguity problem can be artfully solved by synthesizing the output signals from the vector and scalar structures. The hydrophone's ability of azimuth measurement is tested with a standing-wave tube and the error of direction of arrival (DOA) estimation is within 1°. Moreover, the composite hydrophone remains the frequency response trend of the cilium MEMS vector hydrophone. We believe that this work is a significant advance in the development of MEMS hydrophone and should place a solid base for relevant engineering applications.