Abstract: An particle separation microstructure comprising a body and a flow channel extending through the body, having an inlet and an outlet for receiving a flow of particles therethrough. The flow channel comprises opposing first and second walls disposed in a spaced-apart relationship and at least one protrusion extending from the first wall into the flow channel and extending along a length of the flow channel. At least a portion of one of the first and second walls is reversibly actuatable between a first and a second position and the first and second walls are substantially parallel in the second position. In the first position the flow channel is open for receiving the flow of particles and in the second position the at least one protrusion abuts the second wall and the flow channel is constricted for restricting the flow of particles and separating particles from the flow of particles.