This study presents a dielectrophoresis-based liquid metal (LM) droplet control microfluidic device. Six square liquid metal electrodes are fabricated beneath an LM droplet manipulation pool. By applying different voltages on the different electrodes, a non-uniform electric field is formed around the LM droplet, and charges are induced on the surface of the droplet accordingly, so that the droplet could be driven inside the electric field. With a voltage of ±1000 V applied on the electrodes, the LM droplets are driven with a velocity of 0.5 mm/s for the 2.0 mm diameter ones and 1.0 mm/s for the 1.0 mm diameter ones. The whole chip is made of PDMS, and microchannels are fabricated by laser ablation. In this device, the electrodes are not in direct contact with the working droplets; a thin PDMS film stays between the electrodes and the driven droplets, preventing Joule heat or bubble formation during the experiments. To enhance the flexibility of the chip design, a gallium-based alloy with melting point of 10.6 °C is used as electrode material in this device. This dielectrophoresis (DEP) device was able to successfully drive liquid metal droplets and is expected to be a flexible approach for liquid metal droplet control.

Digital isolation chips are widely used in signal or energy transmission between high-current and low-current circuit, which can significantly improve the reliability and security of systems. Circuit power density and efficiency would be greatly limited by the common mode interference, which is induced by isolation transformers of digital chips. In this current work, the impact of common mode current from the transformer in digital isolation chips on electromagnetic radiation was studied by simulation analysis. With regard to the radiation electric field caused by common mode currents generated in the transformer, a three-dimensional (3-D) electromagnetic field model was developed for the digital isolation chip. In addition, the effect of various fitting functions of the common mode current on radiation was investigated using this model. The results of this investigation provide great significance to the design and optimization of digital isolation chips.