Negative to zero Poisson’s ratio adjustable UV-PDMS flexible metamaterials fabricated by using 3D photolithography

• Mechanical metamaterials (MMs) are fabricated using 3D photolithography. • Rubber-like MMs with submillimeter unit structures are fabricated. • MMs with different linewidths are fabricated using single mask pattern. • Negative to zero Poisson’s ratio of MMs are controlled by adjusting linewidth. Mechanical metamaterials (MMs) exhibit mechanical characteristics that are challenging to achieve using existing isotropic materials. Due to their unique characteristics, MMs hold significant potential for applications in diverse fields such as space, architecture, and robotics. This study proposes a method for processing and tuning the mechanical characteristics of MMs composed of UV-curable silicone rubber (UV-PDMS) submillimeter-sized thorough holes, specifically for integration into flexible microdevices. We focused on the microfabrication of polymeric materials with elastic limits and MMs regions, which have traditionally been difficult to achieve. Using 3D photolithography, UV-PDMS was successfully processed to incorporate submillimeter-sized through-holes. Furthermore, MMs with different linewidths were fabricated using from an identical mask pattern by only adjusting the UV incidence angle and exposure dose using 3D photolithography. The resulting flexible MMs exhibited tunable Poisson’s ratios within the range of −0.16 to −0.06.