Electrowetting-on-Dielectric by Wireless Powering

Abstract

Electrowetting-on-dielectric (EWOD), in which microdroplets are manipulated using electrical inputs, has drawn a great deal of attraction with applications of digital lab-on-a-chip and hot-spot cooling. In most EWOD actuations, the commonly used powering method is wired transmission, which may not be suitable for isolating and employing EWOD devices in hard-to-reach areas. In this study, we investigate wireless power transmission for EWOD utilizing inductive coupling. Since EWOD is typically operated by a high-input voltage although the current is minimal, wireless EWOD also requires a similarly high voltage at the receiver, unlike conventional inductive coupling. To meet this condition, the resonant inductive coupling method at a high resonant frequency is introduced and investigated. To optimize the transmission efficiency, we study the effects of many parameters, such as the frequency, inductance, and capacitance at the transmitter and receiver, the gap between the transmitter coil and receiver coil, and the droplet size, by measuring the voltage at the receiver and the contact angle of the droplet placed on a wirelessly operated EWOD chip. In addition, by applying amplitude modulation to the resonant inductive coupling, wireless AC-EWOD, which generates droplet oscillations and is a common mode for EWOD droplet handling, is also achieved. Finally, it is successfully demonstrated that a droplet is transported laterally by using an array of electrodes, which is also powered by an amplitude-modulated wireless signal.

Inherent amplitude demodulation of an AC-EWOD (electrowetting on dielectric) droplet

“…[5][6][7][8][9][10] In the mean time, being aligned to the current trend for the implantation of microfluidics inside animal and human bodies, EWOD is currently looking for integration with wireless powering. 11,12 Since the EWOD works well with AC input signals, an easy and immediate approach to a wireless EWOD may be to utilize magnetic induction using transmitter and receiver coils. Typically, this wireless powering method uses a transmitting signal of high frequency (.…”

“…In order to address this issue, Byun and Cho recently introduced amplitude modulation and experimentally demonstrated droplet oscillations using amplitude modulated (AM) signals, in which the frequency of the envelope signal was within the dynamic range of the droplet oscillation while the transmission frequency was well above the envelope signal frequency, in order to achieve an efficient transmission. 12 In the experiment, however, the tested range was narrow, and our understanding of the fundamental properties of AM EWOD systems was very limited.…”

Design and characterization of a passive, disposable wireless AC-electroosmotic lab-on-a-film for particle and fluid manipulation

“…Operating at high voltages can have detrimental effects on bioparticle viability and if used improperly, may cause detachment of biomolecules resulting from bioparticle death [61]. Moreover, their functionality is generally limited to only one microfluidic function as in the case of other devices used for particle concentration [30], droplet manipulation [32][33][34][35][36], and fluid pumping [36]. The operational functionality of the LOF presented in this work is truly reconfigurable and its functionality can be externally and wirelessly controlled by adjusting the voltage level Table 1 Comparing characteristic of proposed wireless lab-on-a-film with previously published wireless lab-on-a-chips.…”

“…Recently, the AM scheme has been used for implementation of wireless electrowetting-on-dielectric (EWOD) devices [32][33][34][35]. Byun et al has presented a wireless EWOD device for droplet oscillation and transportation [32,35].…”

Thermal analysis of wirelessly powered thermo-pneumatic micropump based on planar LC circuit

“…The heat generated from the frequency sensitive inductor-capacitor (LC) circuit can be controlled simply by tuning the external field frequency, rather than the field intensity [19]. This feature was exploited in powering the pumping device using various transmitter-receiver configurations, including spool-type [20,21] and metal disc [22,23] receiver coils. Despite that, they not well suited for transdermal application due to issues related to the bulky devices and not compatible with conventional MEMs fabrication technique [24].…”