A 2D Tunable Frequency Selective Absorber Based on Liquid Metal

This paper describes a 2D tunable frequency selective absorber that incorporates a liquid metal and NaOH solution. The structure consists of circular chambers and small steps on a 3D printed substrate, where the radius of liquid metal [eutectic gallium indium (EGaIn)] can be controlled by electrochemical method. The novelty of the proposed design lies in its reconfigurable response, depending on the size of EGaIn on a 2D surface. By changing the radius of EGaIn, the unit cell of frequency selective absorber is capable of achieving four tunable states in simulation. Experimental results show the circular EGaIn patch can be easily created and controlled by DC bias, and produces a tunable absorption peak of 25-30 dB.