3D micromolding of seed-like probes for self-burying soft robots

Abstract

Here, we propose a microfabricated soft probe for soil drilling inspired by the seeds of the Erodium malacoides plant. Firstly, we studied the morphology and biomechanics of the head of Erodium, which is called capsule. Secondly, based on the extracted biological parameters, we designed the artificial capsule-like probe. Then, we microfabricated artificial capsules using a 3D micromolding approach via two-photon lithography in combination with casting of biodegradable thermoplastic polycaprolactone polymer (PCL). Finally, we tested and characterized the penetration forces of natural and artificial capsules in different substrates, including natural and artificial soils with different particle sizes. This focused research on material characterization and fabrication methodology shows great potential for prototyping seed-inspired miniature probes for soil penetration, which may be embedded in ad hoc built soft robots. Such robots can find applications in natural fields for in situ monitoring of soil parameters (e. g. humidity) and for improving the preservation of natural ecosystems.