"Null" flow sensor
First Claim
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1. A fluid flow rate measurement device comprising:
- a substrate of semiconductor material from which is micromachined a beam having first and second free ends and a pivot structure midway between the first and second free ends about which the beam is capable of pivoting, said first and second free ends overlying first portions of the substrate defining a channel and a cavity respectively;
further portions of the substrate adjacent said first portions, which further portions carry electrically conductive deposits thereby forming first electrode structures, and the first and second free ends of the beam having at least partially deposited thereon electrically conductive material defining further electrode structures to cooperate with said first electrode structures to form a plurality of capacitor electrode structures adapted to carry a variable electrical charge in order to exert an electrostatic force to counteract pivoting of the beam caused by a differential force exerted across the beam by fluid flowing into the cavity and through the channel.
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Abstract
A flow sensing device includes a semiconductor substrate 31 and a pivoted beam 1. Below one half of the beam is a channel 7 running throughout the substrate 31, and below the other half of the beam is a cavity 8. During operation, a differential force exists across the beam, and the amount of force required to compensate for this differential force is indicative of the rate of fluid flow.
9 Citations
4 Claims
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1. A fluid flow rate measurement device comprising:
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a substrate of semiconductor material from which is micromachined a beam having first and second free ends and a pivot structure midway between the first and second free ends about which the beam is capable of pivoting, said first and second free ends overlying first portions of the substrate defining a channel and a cavity respectively; further portions of the substrate adjacent said first portions, which further portions carry electrically conductive deposits thereby forming first electrode structures, and the first and second free ends of the beam having at least partially deposited thereon electrically conductive material defining further electrode structures to cooperate with said first electrode structures to form a plurality of capacitor electrode structures adapted to carry a variable electrical charge in order to exert an electrostatic force to counteract pivoting of the beam caused by a differential force exerted across the beam by fluid flowing into the cavity and through the channel. - View Dependent Claims (2, 3, 4)
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Specification