Pressure sensing device for rheometers
First Claim
1. A plate having a plurality of pressure sensors at spaced locations therein to measure pressure exerted against a measuring surface of the plate at the locations of the pressure sensors, comprising:
- a plate having a measuring surface against which a liquid can act;
a plurality of cavities in the plate;
deformable portions of the measuring surface of the plate extending over the cavities and resiliently deformable into the cavities in response to pressure applied to the deformable portions of the measuring surface; and
sensors cooperable with the deformable portions to sense the deformation of such deformable portions, the deformation of the deformable portions being indicative of the pressure applied to such deformable portions.
1 Assignment
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Accused Products
Abstract
An improved rheometer plate includes a smooth sensing surface with monolithically integrated miniature pressure sensors which do not interfere with the smooth surface. Pressure sensing diaphragms formed by the smooth surface deflect in response to local pressures against the surface to enable the measurement of unperturbed local pressures of materials sheared between plates. The pressure sensors are sufficiently small that measured pressures are considered to be significantly local properties compared to the size of the plate. Normal stress differences and viscosity of fluid are measured accordingly. The membrane covers a plurality of wells or recesses with pressure sensors located in the wells to measure the deflection of the membrane over the wells. Capacitive or other sensors may be used. The rheometer plate can be used as part of a slit rheometer with a slit of varying dimensions.
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Citations
26 Claims
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1. A plate having a plurality of pressure sensors at spaced locations therein to measure pressure exerted against a measuring surface of the plate at the locations of the pressure sensors, comprising:
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a plate having a measuring surface against which a liquid can act;
a plurality of cavities in the plate;
deformable portions of the measuring surface of the plate extending over the cavities and resiliently deformable into the cavities in response to pressure applied to the deformable portions of the measuring surface; and
sensors cooperable with the deformable portions to sense the deformation of such deformable portions, the deformation of the deformable portions being indicative of the pressure applied to such deformable portions. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A pressure sensor, comprising:
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a wafer having opposite sides, one side forming a smooth measuring surface against which a liquid may exert pressure;
a plurality of wells extending into the wafer from the side opposite the measuring side, said wells forming thin deformable portions of the wafer between ends of individual wells and the smooth measuring surface, said thin deformable portions deformable with respect to an individual well in response to pressure applied to the smooth measuring surface over said individual well; and
detectors associated with individual wells of the plurality of wells to detect the deformation of the thin portion of the wafer with respect to individual wells and to provide an output indicative of the pressure applied to that thin section. - View Dependent Claims (17, 18)
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19. A pressure sensor, comprising:
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A substrate;
a plurality of wells extending into the substrate from a joining surface of the substrate;
a wafer having opposite sides, one side forming a smooth measuring surface against which a liquid may exert pressure and an opposite side joined to the joining side of the substrate, the wafer forming thin deformable portions of the wafer where the wafer extends over a well, said thin deformable portions deformable with respect to an individual well in response to pressure applied to the smooth measuring surface over said individual well; and
detectors associated with individual wells of the plurality of wells to detect the deformation of the thin portion of the wafer with respect to individual wells and to provide an output indicative of the pressure applied to that thin section. - View Dependent Claims (20)
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21. A slit rheometer comprising:
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a body;
a plurality of recesses in the body each having different dimensions and being connected together in series to form a flow passage through the body;
means for causing flow of fluid through the recesses; and
a plurality of pressure sensors associated with each recess to provide indications of pressure exerted by fluid in the recess against the recess at the location of each of the pressure sensors associated with the recess. - View Dependent Claims (22, 23, 24, 25)
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26. A method of producing a plate with a plurality of pressure sensors, comprising the steps of:
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obtaining a wafer and a substrate;
forming a plurality of wells in one of the wafer or the substrate;
forming sensor components in the wells;
joining the wafer and substrate to form the plate in a manner so that the wells form cavities in the plate with thin deformable portions of the wafer forming a part of each cavity, the thin deformable portions of the wafer deforming with respect to the cavities in response to liquid pressure applied to the plate, and the sensor components being arranged in the wells to measure the deformation of respective thin sections.
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Specification