Microfluidic solid phase suspension transport with an elastomer-based, single piezo-actuator, micro throttle pump

Abstract

We report a Micro Throttle Pump (MTP) which has been shown to pump 5 microm diameter polystyrene beads at a concentration of 4.5 x 10(7) beads ml(-1). This new MTP design is constructed in a straightforward manner and actuated by a single piezoelectric (PZT) element. Maximum flow rates at 800 Hz drive frequency of 132 microl min(-1) with water and 108 microl min(-1) with a bead suspension were obtained. Maximum back-pressures of 6 kPa were observed in both cases. The reported MTP employs specific location of distinct internal microfluid structures cast in a single compliant elastomeric substrate to exploit the opposing directions of flexure of regions of a piezoelectric-glass composite bonded to the elastomer. By this novel means, distinct flexural regions, exhibiting compressive and tensile stresses respectively, allow both the pump's integrated input and output throttles and its pump chamber to be actuated concurrently by a single PZT. To support MTP design we also report the characterisation of an individual throttle's resistance as a function of actuator deflection and discuss the underlying mechanism of the throttling effect.

Whole blood pumping with a microthrottle pump

“…21 However, despite their modest ratios, relative to conventional, fully closing valves, pumps incorporating a pair of such throttles demonstrate pumping efficiencies close to those of micropumps incorporating conventional, fully closing valves. 20 In addition, as a result of the lack of full throttle closure, pumps utilizing microthrottles have been demonstrated to be tolerant of high particle concentrations 22 and are not affected by interfacial stiction, which is commonly exhibited if polydimethylsiloxane ͑PDMS͒ contacts another surface, 23 and are therefore capable of operating at high actuator frequencies ͑ca. 1800 Hz͒, in the context of PDMS devices.…”

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].…”

Microvalves and Micropumps for BioMEMS

“…Flow rate is inversely proportional to the fourth power of the hydraulic radius of a microchannel, so even a small reduction in a channel's cross-sectional area can produce a significant increase in flow resistance and consequently a drop in flow rate. Tan and coworkers reported the development of a microthrottling pump (MTP) [80][81][82] that manipulated the flow resistance using a pair of microthrottles molded into a PDMS substrate. An offset in PZT disk placement with respect to the throttles results in bimorphic flexion of the glass diaphragm such that the throttles operate out of phase from one another.…”

“…In another strategy developed by Yang and coworkers [83], a planar diffuser-nozzle channel design is used for a piezoelectric/PMMA device. When designing the pumping chamber for piezoelectric actuators, it should be noted that circular pumping chambers could induce the formation of microvortices during pump operations [80,83]. [81]).…”