A research team led by Professor Wu Dong from the Micro-Nano Engineering Laboratory at the University of Science and Technology of China, Chinese Academy of Sciences, has proposed a femtosecond laser dual-process strategy for writing multiple materials, resulting in the creation of micro-mechanical joints composed of thermosensitive hydrogels and metallic nanoparticles. Subsequently, they developed multi-joint humanoid micromachines with various deformation modes. The research findings were published in “Nature Communications”.
Femtosecond Laser Dual-Process for Light-Triggered Multi-Joint Microactuators
In recent years, femtosecond laser two-photon polymerization technology has been widely applied in the manufacturing of various functional microstructures due to its true three-dimensional processing capability with nanometer precision. These microstructures show great application prospects in fields such as micro-nano optics, micro-sensors, and micro-machine systems. However, utilizing femtosecond lasers for composite multi-material processing and further constructing multi-modal micro-nano mechanics remains a significant challenge.
The researchers introduced that the femtosecond laser dual-process strategy includes using asymmetric two-photon polymerization to construct hydrogel joints and laser reduction deposition of silver nanoparticles in localized regions of the joints. Among them, the asymmetric photopolymerization technology creates anisotropic crosslinking density in the localized regions of the hydrogel micro-joints, ultimately allowing for controllable bending deformation in direction and angle. In-situ laser reduction deposition enables precise processing of silver nanoparticles on the hydrogel joints. These silver nanoparticles exhibit strong photothermal conversion effects, resulting in excellent characteristics of ultra-short response time and ultra-low driving power for the modal switching of multi-joint micromachines.
As a typical example, eight micro-joints were integrated into a humanoid micromachine. Subsequently, spatial light modulation technology was utilized to achieve multi-focus beams in 3D space, thereby precisely stimulating each micro-joint. The coordinated deformation among multiple joints enables the humanoid micromachine hand to complete various reconfigurable deformation modes. Ultimately, a “dancing microrobot” was realized at the micron scale. As a proof of concept, the researchers designed the distribution and deformation direction of the micro-joints, allowing the dual-joint micro-mechanical arm to collect multiple micro-particles in both the same and opposite directions.
The researchers stated that the femtosecond laser dual-process strategy can construct deformable micro-joints in various three-dimensional microstructures, achieving multiple reconfigurable deformation modes. In the future, micro-mechanical hands with various deformation modes will show great application prospects in micro cargo collection, microfluidic operations, and cell manipulation.Related link:https://dx.doi.org/10.1038/s41467-023-40038-x
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