Wirelessly Powered Electrowetting-on-Dielctric (EWOD)

Recently, EWOD (Electrowetting on dielectric) has attracted a great deal of interest with applications of digital lab-on-a-chip in which microfluids are manipulated in a discrete form of droplets using electrical inputs. In most EWOD applications, the commonly used powering method is wired transmission, which may not be suitable for implantable lab-on-a-chip applications. In this paper, we will investigate wireless power transmission for EWOD utilizing the inductive coupling. Unlike the conventional inductive coupling, wireless EWOD requires a high voltage (> 50 V) at the receiver side which is connected to the EWOD chip since EWOD naturally operates under high input voltages. To satisfy 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, the inductance and the capacitance at the transmitter as well as receiver, the gap between the transmitter coil and receiver coil, and so on, by measuring the voltage at the receiver and the contact angle of droplets placed on wirelessly operated EWOD chip. In addition, by introducing amplitude modulation (AM) to the resonant inductive coupling, wireless AC electrowetting which generates droplet oscillations and is one of the commonly used operational modes is also achieved.