System and method for run-time hermeticity detection of a capped MEMS device

摘要

Determining if a hermetically sealed MEMs device loses hermeticity during operation. In one embodiment, the MEMs device is an accelerometer. A test signal having an associated frequency above an operational frequency range for the accelerometer is provided to the accelerometer at an input during operation of the accelerometer for sensing an acceleration. The output signal of the accelerometer is filtered at least above the operational frequency range of the accelerometer producing a test output signal. The test output signal is then compared to a predetermined threshold to determine if the amplitude of the test output signal differs from the threshold. If the amplitude of the test output signal differs from the predetermined threshold, an error signal is produced indicating that hermeticity of the accelerometer has been lost.

主权项

1. A method for determining if a hermetically sealed micro-electrical mechanical system linear accelerometer measuring linear accelerations about one or more axes containing a hermetically sealed gas maintains its hermeticity during operation of the accelerometer under acceleration by an external stimulus, the method comprising:
providing the linear accelerometer during operation with a test signal having an associated frequency above an operational frequency range for the linear accelerometer producing a test portion of an output signal from the linear accelerometer; filtering from the output signal the accelerometer frequencies at least below the operational frequency range of the linear accelerometer producing a test output signal, the test output signal not including frequencies within the operational frequency range of the linear accelerometer; determining if the amplitude of the test output signal differs from a predetermined threshold for a predetermined frequency wherein the predetermined threshold is based at least in part on the viscosity of the gas within the linear accelerometer; and if the amplitude of the test output signal differs from the predetermined threshold by a predefined range, producing an error signal indicating that hermeticity of the linear accelerometer has been lost otherwise hermeticity is maintained.