Design and Characterization of 3-Stack MEMS-Based Passive Flow Regulators for Implantable and Ambulatory Infusion Pumps

Passive implantable or portable infusion pumps comprise an energy source to pressurize a drug and a fluidic restriction to determine the delivery rate. MEMS technology enables the design of microfluidic chips that can passively regulate the flow rate and therefore limit the impact of pressure variations on flow accuracy. The device is a triple-stack structure made of silicon and borosilicate with valves associated in parallel. Flow regulation is obtained from the deflection of a silicon membrane that progressively obstructs the valves as the reservoir pressure increases. Samples dedicated to the infusion at 1 ml/h and 1 ml/day have been designed, manufactured and tested. Flow regulation in the pressure range 200-1000mbar was obtained, with an overall flow rate variability of +/-10% with respect to nominal targets. By comparison to commercial devices, these data showed a reduction of the flow variability up to a factor 2.4 and the lowering of the reservoir pressure by a factor 5. A passive flow regulator coupled with an active valve would match the flow control capabilities of the state-of-the-art programmable implantable pumps. Furthermore, these microfluidic chips could be adapted to disposable pumps to improve the flow accuracy during the infusion of potent drugs having short half-lives.