A MEMS acceleration detection device including a housing having a cavity and a spring mass system assembled into the cavity of the housing. A lid enclosing the spring mass system in the cavity and contacting a top surface of the housing.

The invention provides an MEMS device. The MEMS device includes: a substrate, a proof mass, a spring, a spring anchor, a first electrode anchor, and a second electrode anchor, a first fixed electrode and a second fixed electrode. The proof mass is connected to the substrate through the spring and the spring anchor. The proof mass includes a hollow structure inside, and the spring anchor, the first electrode anchor, and the second electrode anchor are located in the hollow structure. The proof mass and the first fixed electrode form a first capacitor, and the proof mass and the second fixed electrode form a second capacitor. There is neither any portion of the proof mass nor any portion of any fixing electrode located between the first electrode anchor, second electrode anchor, and the spring anchor.

An accelerometer as disclosed herein includes a support wafer, a bottom wafer, a top wafer, and an inductive pick-off. The support wafer may define a plane and may comprise a first side, a second side, and a proof mass. The proof mass may be configured to move in the plane defined by the support wafer. The bottom wafer may comprise a first side and a second side, and the first side may be positioned over the first side of the support wafer. The top wafer may comprise a first side and a second side, and the first side may be positioned over the second side of the support wafer. The inductive pick-off may comprise a near field resonant conductive coupling mechanism and may be configured to output a signal indicative of an amount of displacement of the proof mass to electronics.

The present disclosure is directed to micro-electromechanical system (MEMS) accelerometers that are configured for a user interface mode and a true wireless stereo (TWS) mode of an audio device. The accelerometers are fabricated with specific electromechanical parameters, such as mass, stiffness, active capacitance, and bonding pressure. As a result of the specific electromechanical parameters, the accelerometers have a resonance frequency, quality factor, sensitivity, and Brownian noise density that are suitable for both the user interface mode and the TWS mode.

Fully symmetric sensing structures for MEMS devices are disclosed herein. In certain embodiments, a MEMS sensor includes a proof mass that moves in a first direction. The proof mass includes moveable fingers that move with the proof mass. The MEMS sensor further includes fixed fingers that are fixed with respect to the moveable fingers, and the fixed fingers and moveable fingers serve to detect movement of the proof mass. For example, the moveable fingers and the fixed fingers can be interdigitated to form a comb finger set for sensing changes in capacitance arising from movement of the proof mass relative to a substrate. A layout of the fixed fingers is fully symmetric in at least the first direction.