Micro slit viscometer with monolithically integrated pressure sensors
First Claim
1. A slit rheometer for determining the viscosities of liquids comprising:
- a monolithic sensor plate formed from a combination of a pressure sensor membrane and a pressure sensor substrate having at least two cavities formed in one or the other or both of the pressure sensor membrane and the pressure sensor substrate, a portion of the pressure sensor membrane extending over respective cavities of the at least two cavities whereby the portions of the pressure sensor membrane extending over the respective cavities will deflect into the respective cavities upon application of pressure to the portion of the pressure sensor membrane over a respective cavity, the amount of deflection being proportional to the pressure applied to the membrane over the respective cavity, and a pressure sensor formed in each of the plurality of cavities to provide the monolithic sensor plate with a substantially smooth surface and a plurality of independent pressure sensors in the monolithic sensor plate;
a channel substrate configured to form at least one flow channel therein when combined with the monolithic sensor plate with the at least one flow channel having a flow entrance and a flow exit; and
each of said at least one flow channel having at least two individual pressure sensors located therein and spaced sufficiently away from the liquid entrance and the liquid exit whereby a pressure drop of fully developed flow of liquid through the at least one flow channel can be measured.
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Accused Products
Abstract
An improved micro slit viscometer includes a combined micrometer depth rectangular slit flow channel with monolithically integrated multiple pressure sensors in the flow channels and a pumping system that injects a test sample to the channel at a desired flow rate. Pressure sensing diaphragm of the monolithically integrated pressure sensors is smooth to minimize the flow disturbance thereby measuring accurate local pressures. With the measurement of the pressures at various locations of the channel the true viscosity of test sample can be calculated. The viscometer may consist of multiple flow channels and thus the true viscosity at multiple shear rates can be measured simultaneously for a given flow rate thereby obtaining a full viscosity curve as a function of shear rate of non-Newtonian liquids in a much faster manner. The viscometer needs only a miniscule amount of sample, which minimizes a waste of test material. The flow channels and the monolithically integrated pressure sensors are fabricated using microfabriaction processes on wafers and combined, which greatly reduce the production costs.
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Citations
26 Claims
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1. A slit rheometer for determining the viscosities of liquids comprising:
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a monolithic sensor plate formed from a combination of a pressure sensor membrane and a pressure sensor substrate having at least two cavities formed in one or the other or both of the pressure sensor membrane and the pressure sensor substrate, a portion of the pressure sensor membrane extending over respective cavities of the at least two cavities whereby the portions of the pressure sensor membrane extending over the respective cavities will deflect into the respective cavities upon application of pressure to the portion of the pressure sensor membrane over a respective cavity, the amount of deflection being proportional to the pressure applied to the membrane over the respective cavity, and a pressure sensor formed in each of the plurality of cavities to provide the monolithic sensor plate with a substantially smooth surface and a plurality of independent pressure sensors in the monolithic sensor plate; a channel substrate configured to form at least one flow channel therein when combined with the monolithic sensor plate with the at least one flow channel having a flow entrance and a flow exit; and each of said at least one flow channel having at least two individual pressure sensors located therein and spaced sufficiently away from the liquid entrance and the liquid exit whereby a pressure drop of fully developed flow of liquid through the at least one flow channel can be measured. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A method of manufacturing slit rheometers comprising:
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forming at least two cavities in one or both of a pressure sensor membrane and a pressure sensor substrate; combining the pressure sensor membrane with the pressure sensor substrate to create a pressure sensor plate with a portion of the pressure sensor membrane extending over respective cavities of the at least two cavities; forming independent pressure sensors in the at least two cavities; and combining the pressure sensor plate with a channel substrate to create at least one flow channel having a flow entrance and a flow exit through which liquid can flow, the flow channel passing over at least two of the at least two independent pressure sensors in the pressure sensor plate with the at least two independent pressure sensors spaced sufficiently away from the liquid entrance and the liquid exit whereby a pressure drop of fully developed flow of liquid through the at least one flow channel can be measured. - View Dependent Claims (22, 23, 24, 25, 26)
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Specification