Novel approaches to particle tolerant valves for use in drug delivery systems

Abstract Wherever microvalves find application, they face a major problem of particle tolerance. Various approaches to overcome the influence of particles on the behavior of microvalves are known, be it special designs of sealing rims or filtering techniques. In the case of drug delivery systems, accumulation of particles directly affects their reliability, especially when considering long-term applications. Based on our multiple experience in developing microvalves, we report a new approach of integrating a flow restrictor and a control valve in a single device by covering a rigid microchannel with an elastomer membrane. Controlling the pressure onto an elastic membrane, the cross-section of a capillary and thus the flow through a capillary in an experimental setup was reproducibly controlled. This novel concept for a variable flow controller, typically controlling nominal flowrates between 0.1 and 100 ml per day, is aimed to be operated as multistable, particle tolerant system. The capillary device without actuation unit in the presented proof of principle measures 6 mm × 6 mm × 2.5 mm.