Sensors
AssigneeSchlumberger Electronics (U.K.) Limited
InventorsHoward A. Dorey, Bronislaw J. Suski
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Abstract
A solid sensor, for sensing a physical parameter such as pressure, comprises a resonantly vibratable beam formed across a cavity in a substrate by micro-machining, and arranged such that changes in the parameter vary its resonant frequency. The beam either consists of or has deposited on it a material exhibiting piezo-electric effect, so that vibration of the beam can be excited by using the effect. This is achieved using light, either by forming a photodiode in the substrate in or near the beam, so that illuminating the photodiode causes a voltage to be applied to the beam, or, in the case where the piezo-electric material exhibits surface piezo-electric effect, by directly illuminating the beam.
Claims7
A sensor for sensing a physical parameter, the sensor comprising:
- a resonantly vibratable element, formed in a substrate;
- means for exciting resonant vibration of the element;
- and
- means for applying the parameter to the element so as to vary the frequency of vibration thereof in dependence upon the parameter;
- wherein the element comprises a material which exhibits surface piezo-electric effect;
- and
- the exciting means includes means for directing light of suitable wavelength onto the element so as to induce said resonant vibration thereof by virtue of said surface piezo-electric effect.
Dependencies are inferred from the claim text.