A Voxel‐Based Approach for the Generation of Advanced Kinematics at the Microscale

Abstract

In soft robotics, the ability to generate advanced kinematics is a necessary step toward any more sophisticated tasks such as microobject manipulation, locomotion, or configuration changes. To this end, herein, a modular voxel‐based methodology adaptable to any scale and with any soft transducer is presented. The methodology is implemented at the micrometer scale with a one‐step fabrication process. An innovative gray‐tone lithography method using the two‐photon polymerization of photosensitive poly(N‐isopropylacrylamide) hydrogel is developed to print the voxels. Bending, compression, and twisting voxels are designed, printed, and characterized. A voxel consists of an isotropically shrinking active material reinforced adequately with a passive pattern. Each elementary voxel deforms along one degree of freedom and is a building block for superstructures able of advanced kinematics. With a side length of 40 μm, the bending voxel achieves a bending angle of 25º or curvature of . The compression voxel reaches an actuation strain of 40%, and the twisting voxel bends up to 18º. Advanced kinematics are demonstrated by printing complex structures composed of multiple elementary voxels. Herein, a foundation toward soft microrobots capable of performing complex tasks is constituted.

Recent Advances in Multi‐Photon 3D Laser Printing: Active Materials and Applications

“…fabricated structural elements for bending compression and twisting deformation, demonstrating complex geometries based on hydrogels featuring advanced kinematics. [ 50 ] Deng et al. presented photoresponsive PNIPAAm‐based microactuators by printing a carbon nanotube doped bilayer structure composed of a responsive layer featuring assembled metamaterial unit cells and a solid nonresponsive layer both printed using similar fabrication conditions.…”

“…In another example, Decroly et al fabricated structural elements for bending compression and twisting deformation, demonstrating complex geometries based on hydrogels featuring advanced kinematics. [50] Deng et al presented photoresponsive PNIPAAm-based microactuators by printing a carbon nanotube doped bilayer structure composed of a responsive layer featuring assembled metamaterial unit cells and a solid nonresponsive layer both printed using similar fabrication conditions. [51] By smart exploitation of the proximity effect -usually reducing resolution quality -the inner part of the metamaterial unit cells was crosslinked with low density allowing for example the fabrication of an artificial light-driven beating heart.…”