MEMS tunneling micro seismic sensor
OwnerFarrokh Mohamadiinventor
Life of this patent
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Abstract
A tunneling accelerometer that can be implemented as a MEMS micro sensor provides differential sensing that minimizes large forces resulting from undesired environmental effects. Used as a seismic sensor, for example, the accelerometer exhibits maximum sensitivity for small seismic waves and suppresses very large seismic activities occurring at shallower depths. In one embodiment, detected current decreases from its maximum for stronger forces and is maximized for small vibrations. In another embodiment, separation of columns of top and bottom tunneling tip pairs, one column from the next, increases gradually so that the tunneling accelerometer suppresses sensitivity to large accelerations such as large seismic activity. A manufacturing process for the accelerometer provides reduced complexity for better yield.
Claims13
A tunneling accelerometer comprising:
- a top layer of tunneling tips and plates connected to an anchor;
- a bottom layer of tunneling tips and plates such that the tunneling tips align with the plates of the top layer and the plates align with the tunneling tips of the top layer in an absence of applied accelerations;
- and
- a proof mass connected to the bottom layer of tunneling tips and plates and configured to allow displacement of the proof mass laterally relative to the anchor in a plane defined by the top and bottom layers in response to applied accelerations so that there is a corresponding lateral displacement between the tunneling tips of the bottom layer and the plates of the top layer as well as the plates of the bottom layer and the tunneling tips of the top layer.
A method comprising:
- aligning a top layer of tunneling tips and plates with a bottom layer of tunneling tips and plates such that the tunneling tips of the bottom layer align with the plates of the top layer and the plates of the bottom layer align with the tunneling tips of the top layer in an absence of applied accelerations, wherein the top layer is connected to an anchor and the bottom layer is connected to a proof mass;
- displacing the proof mass laterally relative to the anchor in a plane defined by the top and bottom layers in response to an applied acceleration so that there is a corresponding lateral displacement between the tunneling tips of the bottom layer and the plates of the top layer as well as the plates of the bottom layer and the tunneling tips of the top layer;
- and
- sensing a tunneling current between the top layer of tunneling tips and plates and the bottom layer of tunneling tips and plates with a sensitivity that is greater for small displacements than for large displacements.
Dependencies are inferred from the claim text.