Elastomer-glass micropump employing active throttles

Abstract

We report a reciprocating microfluidic pump, the Micro Throttle Pump (MTP), constructed in a relatively uncomplicated manner from glass and microstructured poly(dimethylsiloxane)(PDMS). Unconventionally, the MTP employs throttling of fluid flow as distinct from fully-closing valve structures. Accordingly, this technique offers the prospect of solid-phase suspension tolerance. The reported MTP employs piezoelectrically (PZT) actuated deformation of flow constrictions (throttles) fabricated from PDMS at the two ports of a central, PZT actuated pump chamber. By appropriate time-sequencing of the individual PZTs' actuation, pumping can be induced in either direction. PDMS' elasticity further facilitates throttle operation by virtue of allowing significant PZT flexure that is substantially independent of the underlying PDMS microstructure. In contrast, in a rigid substrate such as silicon, deformation is constrained to where underlying microstructured cavities exist and this restricts design options. We describe the construction and performance of a prototype MTP capable of pumping 300 microl min(-1) or alternatively generating a back-pressure of 5.5 kPa. Preliminary modelling of MTP operation is also presented.

Whole blood pumping with a microthrottle pump

“…As previously reported, 18 microthrottle pumps ͑MTPs͒ were developed to utilize "throttling," the use of variable cross-section flow-constrictions ͑microthrottles͒ to control fluid flow. 19 A detailed discussion of microthrottles, their application in microthrottle pumps, and the operating principles of microthrottle pumps has been made previously, 20 therefore only a brief summary is provided here.…”

“…Molds were microfabricated from SU8 ͑Microchem Corp., MA, USA͒ structural photoresist on silicon wafers. The PDMS microstructures were then cast in Dow Corning Sylgard, ® MI, USA͒ 184 PDMS processed in the, previously reported, 18 standard way ͑Fig. 2͒.…”

Piezoelectric unimorph valve assembled on an LTCC substrate

“…thermore, silicon, glass, polymer, and elastomer-based microvalves or throttles have been developed utilizing piezoactuators [11][12][13][14]. Piezoelectric valves are moderately easy to manufacture and provide a comparatively high stroke and actuation force and fast mechanical response [15].…”

A Strip-Type Microthrottle Pump: Modeling, Design and Fabrication

“…Here, various structures of piezoelectric actuator driven micropumps are described. In particular, we found that recently introduced piezoelectric microthrottle (MT) pumps provide good performance [3–6]. These devices are based on throttle valves which do not completely close during operation but rather exhibit sequential openings and closings gated by piezoelectric actuators.…”

“…Absence of freely moving parts, in conjunction with the capacity for partial MT closing and simple design represent advantages, especially in the biomedical field where biological cells should not to be destroyed (squeezed) during pumping. Johnson et al [3] proposed a MT pump based on a polydimethylsiloxane (PDMS) substrate with microvalves (throttles) and a glass membrane covered with piezoelectric (PZT) actuators. They used three PZT actuators and achieved pumping through appropriate sequential actuation of the PZTs.…”