US Patent 7516658 Electro-kinetic pressure/flow sensor

A transmitter senses flow or pressure of a process fluid in a process pipe. The process pipe may include a flow restrictor positioned therein that carries a primary flow of a process fluid. Impulse piping is configured to carry a secondary flow of the process fluid from an upstream side of the flow restrictor to a downstream side. An electro-kinetic element is positioned within the impulse piping and is configured to generate an electro-kinetic potential related to the primary flow. Measurement circuitry in the transmitter is configured to measure the electro-kinetic potential across the electro-kinetic element and relate the electro-kinetic potential to the flow of process fluid through the process pipe.