Abstract
The gallium-based eutectic liquid metal alloys exhibit unique properties of deformability, excellent electrical conductivity and low vapour pressure. The liquid metal-based circuits’ element or actuator have drawn considerable attention in stretchable electronics and microelectromechanical (MEMS) actuators. Yet, the motion of the liquid metal within the electrolyte needs to be precisely regulated to satisfy application requirements. Herein, we investigated the locomotion of liquid metal within the alkaline aqueous solution under electrostatic actuation. The relationship between the travelling speed of the liquid metal slug and the relative influential parameters, such as the voltage amplitude and frequencies of the applied electric field, electrolyte concentration, electrodes distance and the liquid metal volume, were experimentally characterized. A travelling speed up to 20.33 mm/s was obtained at the applied voltage of 4 Vpp at 150 Hz at 6 V DC offset. Finally, the frequency-dependent liquid metal marble movements were demonstrated, namely oscillation and forward locomotion while oscillating. The oscillation frequency was determined by the frequency of the applied alternate current (AC) signal. The remarkable transportation and oscillating characteristic of the liquid metal marble under the electrostatic actuation may present potentials towards the development of flexible electronics and reconfigurable structures.
Highlights
Due to various remarkable advantages, such as reduced agent consumption, smaller analysis volume, less reaction time and increasing device portability, the droplet-based microfluidic has recently played increasing important in the fields of microelectromechanical systems (MEMS) and lab-on-a-chip microfluidic devices [1,2,3]
The chip structure and the fabrication processes of the liquid metal-based microfluidic device were depicted in Figure 1, which incorporated a liquid metal slug confined in the alkaline solution-filled channel and two graphite electrodes located on both ends of the liquid metal
To the pumping pumping performance performanceofofthethe proposed surface tension-induced device, experimentally investigated the relationship between the actuation speeds of the liquid metal slug we experimentally investigated the relationship between the actuation speeds of the liquid metal slug and the the electrolyte electrolyte concentration, concentration, voltage voltage magnitudes magnitudes and and driving driving frequencies frequencies of of the the applied applied electric electric and field, as as well well as as the the galinstan galinstan liquid liquid metal metal droplet droplet volume
Summary
Due to various remarkable advantages, such as reduced agent consumption, smaller analysis volume, less reaction time and increasing device portability, the droplet-based microfluidic has recently played increasing important in the fields of microelectromechanical systems (MEMS) and lab-on-a-chip microfluidic devices [1,2,3]. Unlike the traditional pumping effect requiring moving parts, electrowetting is a popular electrocapillary phenomenon for transferring droplets, in which the interface tension between the driving electrode and conducting liquid phase was electrostatic-adjusted through the external potential gradient acting on the liquid droplet. The EWOD actuation mechanism has the merit of no moving parts, no heating of the transporting medium and lower power consumption, the fabrication of a dielectric-coated electrode such as ITO thin film in the microchannel is complicated It always required several electrodes and intricate control circuit to accomplish long distance transportation. While recently, another surface tension-induced mechanism, the continuous electrowetting, was introduced to actuate the discrete liquid metal by tailoring the liquid–liquid interfacial tension [42,43,44,45]. We determined the dependence of droplet pumping mode on the frequency of the input AC signal, including unidirectional pumping, oscillation and forward locomotion while oscillating
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