Sensors and Actuators A 233 (2015) 1–8 Contents lists available at ScienceDirect Sensors and Actuators A: Physical journal homepage: www.elsevier.com/locate/sna Wireless powered thermo-pneumatic micropump using frequency-controlled heater Pei Song Chee a,b , Marwan Nafea Minjal a , Pei Ling Leow a , Mohamed Sultan Mohamed Ali a,c,∗ a Faculty of Electrical Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia b Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, 43000 Bandar Sungai Long, Selangor, Malaysia c Flextronics, Pelabuhan Tanjung Pelepas (PTP), 81560 Gelang Patah, Johor, Malaysia a r t i c l e i n f o Article history: Received 28 January 2015 Received in revised form 9 June 2015 Accepted 17 June 2015 Available online 22 June 2015 Keywords: Wireless actuation Micropump Thermo-pneumatic a b s t r a c t This paper reports a novel, wirelessly powered micropump based on thermo-pneumatic actuation using a frequency-controlled heater. The micropump operates wirelessly through the energy transfer to a frequency-dependent heater, which was placed underneath the heating chamber of the pump. Heat is generated at the wireless heater when the external magnetic field is tuned to the resonant frequency of the heater. The enclosed air in the chamber expands and forces the liquid to flow out from the reservoir. The developed device is able to pump a total volume of 4 ml in a single stroke when the external field frequency is tuned to the resonant frequency of the heater at the output power of 0.22 W. Multiple strokes pumping are feasible to be performed with the volume variation of ∼2.8% between each stroke. Flow rate performance of the micropump ranges from 1.01 L/min to 5.24 L/min by manipulating the heating power from 0.07 W to 0.89 W. In addition, numerical simulation was performed to study the influence of the heat transfer to the sample liquid. The presented micropump exclusively offers a promising solution in biomedical implantation devices due to its remotely powered functionality, free from bubble trapping and biocompatible feature. © 2015 Elsevier B.V. All rights reserved. 1. Introduction Micropumps have been widely applied in self-contained biomedical and micro-total-analysis system (TAS) areas, includ- ing transdermal drug delivery and therapeutic implants devices due to their precise dosage controllability. Numerous actuation mechanisms have been developed towards the compatibility of the micropump devices for clinical applications including refractory epilepsy treatment [1], in-vitro diabetics injection [2], fibroblast growth factor (bFGF) controlled for tissue regeneration [3] and pain management [4]. Of other actuation mechanisms such as pneumatic [5–7], piezoelectric [8,9] and electromagnetic principles [10–12], thermo-pneumatic actuation benefits from low operat- ing voltage and no involvement of external peripheral driving equipment setup [13], making it a promising option for clinical biomedical usage. A thermo-pneumatic micropump can be operated through the motion of the membrane’s deflection induced by the heating and cooling of the air due to the temperature gradient of the heating ∗ Corresponding author. region [14,15]. The pump, in order to control its flow direction, is often coupled with a pair of passive check valve [16] or active valve. Alternatively, a series of multiple actuators arrangement generates a peristaltic motion, which can also convey the flow in a desired direction [17,18]. In these approaches, however, the devices tend to have limited longevity due to the aging and easy tearing of the moving elements such as the thin elastic membrane and flap valves. These constraints deteriorate when multiple actuators are involved. Moreover, they are sensitive to the trapping of bubbles within the moving boundary, and eventually weaken the pump- ing performance [19]. A straight forward single stroke micropump can potentially address the above-mentioned issues [20]. In this case, the liquid is pushed from a pre-filled reservoir to the out- let microchannel based on the volume expansion of a trapped air upon heating operation. This actuation mechanism eliminates the risk from the mechanical failure of the moving elements and was successfully deployed in portable point-of-care diagnostics [21] and discrete droplet manipulation [22]. Nonetheless, the mobil- ity of the devices was severely restrained by the utilization of a wired and battery interface, which further narrows their applica- tion ranges. The ability of wireless power and control of the thermal operation appears to be a key to promote the practicality of the http://dx.doi.org/10.1016/j.sna.2015.06.017 0924-4247/© 2015 Elsevier B.V. All rights reserved.