MEMS gravity sensors for imaging density anomalies

Gravimeters measure small changes in the local gravitational acceleration. They are applied for environmental monitoring, oil and gas prospecting and defence and security. Gravimeters used in these applications have a remarkable sensitivity but at a cost of being bulky and very expensive. Recently, a micro-electrical mechanical system (MEMS) gravimeter has been developed, which was cheap, had a comparable sensitivity to commercial gravimeters and maintained its stability over long timescales (10−6 Hz). In this paper we discuss to replace the current shadow sensor readout with an on-chip interferometer. This new readout has a higher sensitivity so that the device can be more robust and reduces the system size. The design of this readout is discussed and the first experimental results are presented. The new readout improves the imaging capabilities of density anomalies of the device.