3D printing of high-efficiency biomimetic tendon connection structure for biohybrid robots.

Biohybrid robots actuated by living cells/tissues are promising candidates for biomedical and environmental monitoring applications. However, conventional connection methods between biological materials and mechanical bodies in biohybrid robots create weak links in mechanical transmission at their connection interfaces, seriously limiting the motion performance of biohybrid robots and restricting their application. To address this limitation, inspired by the structure of natural bullfrog tendons, an elastic connection structure with coiled fiber morphology was designed and manufactured through 3D printing. The energy storage density of the connection structure is 9.367 × 10^-6 mJ·mm^-3, and the release velocity of elastic recoil is 4.695 mm·s^-1. Furthermore, a biohybrid robot with the elastic connection structure was constructed, achieving a motion speed of 192.35 μm·s^-1. Compared to robots without elastic structures, robots with elastic structures have improved performance by approximately 122 %. We believe that this research has the potential to provide possibilities for designing faster robots in the future and bring breakthroughs to the field of tissue engineering and microrobot technology. STATEMENT OF SIGNIFICANCE: Conventional connection methods between biological materials and mechanical bodies in biohybrid robots create weak links in mechanical transmission at their connection interfaces, seriously limiting the motion performance of biohybrid robots. Inspired by the structure of natural bullfrog tendons, we designed a connection method and manufactured an elastic connection structure with coiled fiber morphology by 3D printing that mimics tendons. Then, we constructed a biohybrid robot with the elastic connection structure. Compared to robots without elastic structures, robots with elastic structures have improved performance by approximately 122 %. We believe that this research has the potential to provide possibilities for designing faster robots in the future and bring breakthroughs to the field of tissue engineering and microrobot technology.