In some embodiments, a micro electro mechanical system (MEMS) includes a proof mass, sense electrodes, sense circuitry, and a frequency matching circuitry. The proof mass is configured to move responsive to stimuli. The sense electrodes are configured to generate a signal responsive to the proof mass moving. The sense circuitry is coupled to the sense electrodes. The sense circuitry is configured to receive the generated signal and further configured to process the generated signal. The frequency matching circuitry is configured to apply a DC voltage to the sense electrodes. The DC voltage is configured to change a stiffness of a spring of the proof mass. According to some embodiments, the change in the stiffness of the spring matches a resonance frequency between a sense mode and a drive mode. According to some embodiments, the sense electrodes are a comb structure.

Accelerometers and associated techniques for detecting motion are described. For a resonant accelerometer, an externally-applied acceleration can cause a change in the electrical spring constant K.sub.e of the electromechanical system. A resonant accelerometer can be driven to resonate in a bulk acoustic wave mode of vibration, which can have a high resonant frequency. Other accelerometers and associated techniques are disclosed.

The invention relates to a sensor device which has a carrier material, in particular a piezoelectric carrier material. Furthermore, the sensor device comprises at least one interdigital transducer, which is configured as a transmitter (IDTs) and as a receiver (IDTe) and is arranged on the carrier material, or at least one interdigital transducer, which is configured as a transmitter (IDTs) and at least one interdigital transducer, which is configured as a receiver (IDTe) and is also arranged on the carrier material. The sensor device further comprises at least one mechanical resonator (MR), which is arranged on the carrier material at a distance A from the IDTs and at a distance B from the IDTe, wherein the sensor device is set up so that a surface wave emitted by the IDTs as a transmit signal causes the MR to vibrate mechanically and a surface wave emitted by the vibrating MR travels as a receive signal in the direction of the IDTe and triggers a measurement signal in the latter.