US Patent 7290441 Micro slit viscometer with monolithically integrated pressure sensors

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.