Voltage-tunable acoustic metasheet with highly asymmetric surfaces

We report the experimental demonstration of a voltage-tunable acoustic metasheet device with two highly asymmetric surfaces, made by combining two decorated membrane resonators (DMRs) separated by a sealed air column. The front surface of the metasheet is impedance matched to air and perfectly absorbing, while the back surface is hard and totally reflecting. When a suitable DC voltage is applied to the back side of the DMR via proper electrodes, the back surface of the metasheet can be tuned to impedance matched to air and perfectly absorbing, while the front surface is totally reflecting. The metasheet also exhibits high transmission contrast around two frequencies. The tunability of the reflection is over 23 dB at 388 Hz and that of the transmission is over 33 dB at 240 Hz and 590 Hz with 600 V of applied voltage.