Novel Structure for a Pneumatically Controlled Flow Regulator With Positive Gain

In this paper, a novel structure for a continuous flow regulator using pneumatic actuation is designed and integrated "in-channel." Unlike other pneumatically actuated devices, the present one provides a positive gain, so that when the control pressure is increased, the working flow rate is also increased, owing to the decrease in resistance to flow in the working channel. This novel structure allows normally closed flow regulators to be opened using only a positive pressure source and makes it possible to control all pneumatic devices in a chip without having to employ vacuum sources. The flow regulator has been fabricated using SU-8, and its behavior is studied using the theory of thin plates and by numerical simulation. The behavior is also experimentally characterized, and its characteristic curves are provided, validating the proposed structure. The device fabricated using this structure has a maximum positive gain of 6.8 mL/(min . bar) for a control pressure of gas up to 1600 mbar and a working pressure of liquid up to 300 mbar in order to control flow rates in the range of milliliters per minute.