Climbing mini-machines using plant-inspired micropatterned adhesive wheels fabricated via two-photon lithography

Abstract

Here, we report a microfabricated untethered lightweight mobile climbing machine with plant-like micropatterned adhesive wheels for complex and unstructured three-dimensional (3D) surfaces. By taking inspiration from the ratchet-like climbing mechanism of the hook climber Galium aparine, we first designed a custom-made machine using two millimeter-scale wheels with bioinspired directional microhooks for mechanical interlocking. Secondly, we fully microfabricated the machine via two-photon lithography, a high-resolution 3D additive manufacturing technique. Then, we characterized the shear forces of the microhooks over natural complex surfaces, like plant leaves. Finally, we demonstrated the climbing behavior of the machine over an inclined slope covered by leaf tissues, as well as its ability to carry a payload. Our research shows potential for prototyping sustainable climbing plant-like small-scale machines for exploration and inspection of unstructured and/o $r$ confined terrains, which paves the way for future applications in environmental monitoring and ecosystem conservation.