Ultraminiature single-crystal sensor with movable member
First Claim
1. A solid-state, capacitive transducer having at least one movable member responsive to a physical force applied thereto, the transducer comprising:
- an integrally formed structure made from single-crystal silicon semiconductor material and having a movable member which is movable in response to a physical force applied thereto, and a rim portion that extends at least around a part of the periphery of and mechanically supports the movable member, the movable member and the rim portion each being heavily impregnated with at least a first material which alters an etching characteristic thereof in comparison to single-crystal material which is identical to the heavily impregnated material of the movable member and rim portion except for containing substantially less of such first material; and
a capacitor having first and second electrically conductive plates, the first plate being arranged to move with the movable member, thereby allowing the capacitance of the capacitor to be adjusted in response to the physical force applied to the movable member.
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Accused Products
Abstract
A capacitive pressure sensor suitable for making highly sensitive, low pressure measurements is disclosed. The sensor may be mounted into a 0.5 mm OD catheter suitable for multipoint pressure measurements from within the coronary artery of the heart. The sensor employs a transducer which consists of a rectangular bulk silicon microdiaphragm several hundred microns on a side by two microns thick, surrounded by a supporting bulk silicon rim about 12 microns thick. Both the diaphragm and the rim are defined by a double diffusion etch-stop technique. The transducer fabrication process features a batch wafer-to-glass electrostatic seal followed by a silicon etch, which eliminates handling of individual small diaphragm structures until die separation and final packaging. An addressable read-out interface circuit may be used with the sensor to provide a high-level output signal, and allows the sensor to be compatible for use on a multisite catheter having only two electrical leads.
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Citations
20 Claims
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1. A solid-state, capacitive transducer having at least one movable member responsive to a physical force applied thereto, the transducer comprising:
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an integrally formed structure made from single-crystal silicon semiconductor material and having a movable member which is movable in response to a physical force applied thereto, and a rim portion that extends at least around a part of the periphery of and mechanically supports the movable member, the movable member and the rim portion each being heavily impregnated with at least a first material which alters an etching characteristic thereof in comparison to single-crystal material which is identical to the heavily impregnated material of the movable member and rim portion except for containing substantially less of such first material; and a capacitor having first and second electrically conductive plates, the first plate being arranged to move with the movable member, thereby allowing the capacitance of the capacitor to be adjusted in response to the physical force applied to the movable member. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A miniature transducer, comprising:
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an adjustable capacitor including first and second electrically conductive members arranged in predetermined normal, physical relation to one another, with the first conductive member being a generally flat member, and the second conductive member being movable relative to the first conductive member; and an integrally formed structure made from single-crystal silicon semiconductor material, the structure having a flexible member and a support portion that extends at least around at least a part of the periphery of the flexible member, and mechanically supports the flexible member in a nominal position a predetermined distance from the first electrically conductive member, the flexible member and support portion being electrically conductive and heavily impregnated with at least a first material which alters an etching characteristic thereof in comparison to single-crystal material which is identical to the heavily impregnated material of the flexible member and the support portion except for containing substantially less of such first material; the flexible member constituting the second electrically conductive member of the capacitor, and being sufficiently thin in at least one selected region thereof relative to its overall size to allow the flexible member to move in response to a force applied thereto in a range designed to be measured by said transducer, whereby the movement of the movable member changes the capacitance of the capacitor. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. A miniature force-sensing device having a capacitance which is adjusted by changes in a force to be sensed, comprising:
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a support substrate; and an integrally formed structure made at least primarily of single-crystal silicon material, the structure including (1) a first selected portion constituting a substantially rigid support structure bonded to the support substrate, the first selected portion being impregnated with a first material in a desired first concentration sufficient to alter an etching characteristic of the first selected portion relative to identical single-crystal silicon material containing substantially less of the first material, and (2) a second selected portion constituting a movable member supported by and capable of movement relative to the support structure, the second selected portion being impregnated with a second material in a desired second concentration sufficient to alter an etching characteristic of the second portion relative to identical single-crystal silicon material containing substantially less of the second material; and a force-sensitive adjustable capacitor having first and second electrically conductive plates normally spaced apart from one another, the first electrically conductive member including a generally flat conductive plate supported by the support substrate, and the second electrically conductive plate being at least in part supported by and movable with the movable member, whereby the capacitance of the capacitor is adjustable in response to movement of the movable member by a force applied thereto. - View Dependent Claims (17, 18, 19, 20)
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Specification