Resonant microbeam temperature sensor
First Claim
1. A strain-responsive temperature sensing device, comprising:
- a support structure including a substrate of a first material having a first thermal expansion coefficient and a layer of a second material having a second thermal expansion coefficient different than the first thermal expansion coefficient, the layer of a second material being in intimate contact with the substrate so as to induce strain in said support structure with changes in temperature;
a vibratory element having opposite first and second end portions, and a means for fixing the first end portion and the second end portion to the support structure, to maintain the vibratory element for oscillation at a natural resonant frequency that varies with changes in induced strain in the vibratory element; and
a resonant frequency sensing means for detecting the natural resonant frequency of said vibratory element and for generating an output representing temperature in the region of the vibratory element, based on the natural resonant frequency.
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Accused Products
Abstract
A temperature sensing device employs a resonant polysilicon beam, in combination with electrical circuitry for oscillating the beam at its natural resonant frequency, to sense changes in temperature. The resonant beam is formed as part of a silicon layer, and the silicon layer is in direct contact with a dissimilar material. In one version of the device, the silicon layer is deposited onto a sapphire substrate by low pressure chemical vapor deposition. In another version, the beam is part of a polysilicon layer deposited onto a silicon wafer substrate. The silicon substrate is thinned, then thermoelectrically bonded to a borosilicate glass substrate. In still another version, the silicon substrate is selectively thinned and has deposited thereon a TCE mismatched material. In all versions, temperature is sensed based on a thermal mismatch of the two dissimilar materials. The respective layers expand (and contract) at different rates in response to temperature changes, altering the level of induced axial strain in the resonant beam. The change in induced strain alters the frequency at which the beam oscillates, thereby providing a direct indication of temperature.
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Citations
23 Claims
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1. A strain-responsive temperature sensing device, comprising:
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a support structure including a substrate of a first material having a first thermal expansion coefficient and a layer of a second material having a second thermal expansion coefficient different than the first thermal expansion coefficient, the layer of a second material being in intimate contact with the substrate so as to induce strain in said support structure with changes in temperature; a vibratory element having opposite first and second end portions, and a means for fixing the first end portion and the second end portion to the support structure, to maintain the vibratory element for oscillation at a natural resonant frequency that varies with changes in induced strain in the vibratory element; and a resonant frequency sensing means for detecting the natural resonant frequency of said vibratory element and for generating an output representing temperature in the region of the vibratory element, based on the natural resonant frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification