A piezoelectric valve manifold with embedded sensors for multi-drug delivery protocols

This paper describes a two-valve manifold for use in a dual chamber drug delivery device for pain therapy. The scalable manifold is hybrid assembled with piezoelectric stacks to actuate Si valve seats against a glass substrate. The substrate has two inlets and one outlet; a piezoresistive pressure sensor is embedded in the Si near each of these three ports. The sensors, which permit closed loop control and error monitoring of the flow rate, have a typical sensitivity of 647 ppm/kPa. The 1×1.5×3 cm³ manifold provides modulation and mixing capabilities. In laboratory tests, flow of isopropyl alcohol was regulated from 1.77 mL/hr to 0.028 mL/hr. The manifold design achieves the desired dynamic range for intrathecal drug delivery and can also be used for gas modulation in other contexts.