UV-curable Polydimethylsiloxane Photolithography and Its Application to Flexible Mechanical Metamaterials

Polymers are increasingly being used as flexible structural materials in MEMS.We have focused on UV-cured polydimethylsiloxane (UV-PDMS), which is both photoreactive and highly flexible.In this study, we propose a photolithography-based patterning method to enable the microfabrication of UV-PDMS.The processing conditions related to patterning accuracy were also investigated.Furthermore, as a demonstration of the practical advantages of this processing method, free-standing flexible metamaterials with a negative Poisson's ratio were fabricated and uniaxial tensile tests were performed.The results showed a minimum Poisson's ratio of -1.30.Compared with the same type of specimen fabricated with a common permanent structural photoresist, the UV-PDMS specimen exhibited deformation approximately 12 times larger.