Patent ID: 7217351

Claim:
A valve for controlling flow of a primary fluid in a primary flow channel which comprises a) a valve fluid channel; b) a membrane of a porous dielectric material located in the valve fluid channel so as to divide the valve fluid channel into an inlet part and an outlet part and so that valve fluid flowing between the inlet and outlet parts flows through the said membrane; c) first and second electrodes located for electrical communication with valve fluid in the inlet and outlet parts respectively of the valve fluid channel for application of an electric potential across the membrane in order to promote electro-osmotic flow of valve fluid through the membrane; d) the outlet part of the valve fluid channel being located at least partially within the primary flow channel, at least part of the wall of the outlet part of the valve fluid channel comprising a valve member being a tubular part for expandable diaphragm sleeve, the tubular diaphragm sleeve can be displaced between open and closed positions as a result of valve fluid moving in the valve fluid channel through the membrane into or out of the outlet part of the valve fluid channel so that an increase in fluid pressure in the outlet part of the valve fluid channel causes the tubular diaphragm to expand transversely relative to the valve fluid channel towards the wall of the primary flow channel to cause a reduction in the capacity for flow of the primary fluid in the primary flow channel when it is in the closed position compared with when it is in the open position.