Micro throttle pump employing displacement amplification in an elastomeric substrate

Abstract

We report a micro throttle pump (MTP) with enhanced throttling resulting from beneficial deformation of its elastomer substrate. In the MTP reported, this has doubled the effective deflection of the piezo electric (PZT) actuator with a consequent five-fold enhancement of throttling ratio. This mode of throttling has been modelled by finite element method and computational fluid dynamic techniques whose predictions agreed well with experimental data from a throttle test structure; providing typical throttling ratios of 8:1 at low pressures. The improved throttles have been incorporated in a prototype, single PZT, MTP, fabricated with double-depth microfluidics, which pumped both water and a suspension of 5 µm polystyrene beads at a maximum flow rate of 630 µl min−1 and a maximum back-pressure of 30 kPa at a pumping frequency of 1.1 kHz. This represents an approximate five-fold enhancement of both performance metrics compared to our previous single PZT device.

Whole blood pumping with a microthrottle pump

“…Initial variants of the microthrottle pumps incorporated a defined pump chamber with throttles constricting normal to the axis of compression. 22 Subsequent developments included the use of throttles constricting parallel to the axis of compression implemented within double depth structure, 22 providing enhanced throttling ratios via displacement amplification, 20 effects within pump chambers as reported by Andersson et al 25 The resulting linear microthrottle pumps ͑LMTP͒ demonstrated pumping rates up to 1.4 ml min −1 and the ability to pump against a back pressure of 35 kPa of water. 21…”

“…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.…”

“…The LMTPs were fabricated and assembled in the manner we have previously described in detail, 20 which is briefly summarized here. Molds were microfabricated from SU8 ͑Microchem Corp., MA, USA͒ structural photoresist on silicon wafers.…”

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.…”

Asymmetric fluttering ferromagnetic bar-driven inertial micropump in microfluidics

“…Diverse micropump technologies and working principles have been introduced in previous reports 5–10 and these can be classified according to the installation location (internal vs. external pumps) and pumping schemes 11 (mechanical vs. non-mechanical or passive vs. active pump). For instance, electro-wetting technology 12 was well developed as a fluid transporting method, which can be integrated with any microfluidic system without any external fluidic connections.…”