Trapped fluid microsystems for acoustic sensing
First Claim
1. A micro system for acoustic transduction, the system comprising:
- an input membrane configured to vibrate in response to an excitation from acoustic energy in a medium adjacent the input membrane and external to the system;
a closed, liquid filled, acoustic chamber having chamber walls; and
a conductive membrane wherein the input membrane and the conductive membrane form portions of the chamber walls, wherein the liquid transfers acoustic energy from the input membrane to the conductive membrane, and wherein the conductive membrane is configured to vibrate in response to an excitation from acoustic energy in the liquid adjacent the conductive membrane.
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Abstract
Silicon and glass micromachined (MEMS) acoustic sensors incorporating trapped-liquid architectures are disclosed. The trapped liquid serves as an acoustic transmission medium allowing the input port to the system to be physically separated from the sensing location. The trapped liquid interacts with a conductive, flexible sensing membrane. Sound pressure waves enter the trapped liquid through an input membrane, travel to the sensing membrane, and excite vibrations of the sensing membrane. The vibrations of the sensing membrane are measured using on-chip capacitive sensing. The capacitive sensing structure is formed by the conductive sensing membrane and a fixed conducting top electrode. As the gap between the conductive sensing membrane and the fixed top electrode varies, the capacitance varies, leading to an electrical signal which is the electrical output of the system.
46 Citations
8 Claims
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1. A micro system for acoustic transduction, the system comprising:
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an input membrane configured to vibrate in response to an excitation from acoustic energy in a medium adjacent the input membrane and external to the system;
a closed, liquid filled, acoustic chamber having chamber walls; and
a conductive membrane wherein the input membrane and the conductive membrane form portions of the chamber walls, wherein the liquid transfers acoustic energy from the input membrane to the conductive membrane, and wherein the conductive membrane is configured to vibrate in response to an excitation from acoustic energy in the liquid adjacent the conductive membrane. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification