Near-zero Poisson's Ratio and Large-area Metamaterial Made of UV-PDMS Using Three-dimensional Backside Exposure

In this study a micro-fabrication method is proposed for UV-PDMS, a UV-curable silicone rubber required for flexible polymer MEMS. The three-dimensional backside exposure method for structure fabrication using the flow of liquid UV-PDMS improved the relative patterning error of the dimensions from 40% to 12.5% compared to that with vertical backside exposure. In addition, large-sized specimens consisting of two-dimensional mechanical metamaterial structures were fabricated from UV-PDMS, and the elongation and Poisson's ratio were evaluated by uniaxial tensile testing. The flexible structure of the metamaterial maintained a Poisson's ratio near zero.