New research on achieving femtosecond laser machining of multi joint micromachines

The team of Wu Dong, professor of the Micro/Nano Engineering Laboratory of University of Science and Technology of China, proposed a processing strategy of femtosecond laser two in one writing into multiple materials, manufactured a micromechanical joint composed of temperature sensitive hydrogel and metal nanoparticles, and then developed a multi joint humanoid micromachine with multiple deformation modes (>10). The relevant research results were recently published in Nature Communications.

In recent years, femtosecond laser two-photon polymerization technology has been widely used as a true three-dimensional machining method with nano precision to manufacture various functional microstructures. These microstructures exhibit broad application prospects in fields such as micro nano optics, micro sensors, and micro machine systems. However, it is still highly challenging to utilize femtosecond lasers to achieve composite multi material processing and further construct multimodal micro/nano machinery.

Femtosecond laser two in one processing strategy includes the use of asymmetric two-photon polymerization to build hydrogel joints, and laser reduction deposition of silver nanoparticles in the local area of the joint. Among them, the asymmetric photopolymerization technology makes the cross-linking density of the local area of the hydrogel micro joint produce anisotropy, and finally enables it to realize the bending deformation with controllable direction and angle.

In situ laser reduction deposition can accurately process silver nanoparticles on hydrogel joints. These silver nanoparticles have a strong photothermal conversion effect, which enables the mode switching of multi joint micromachines to exhibit excellent characteristics such as ultra-short response time (30 milliseconds) and ultra-low driving power (<10 milliwatts).

As a typical example, 8 micro joints are integrated into a humanoid micromachine. Subsequently, researchers utilized spatial light modulation technology to achieve multifocal beams in 3D space, thereby accurately stimulating each micro joint. The collaborative deformation between multiple joints promotes the completion of multiple reconfigurable deformation modes in humanoid micro robotic arms. Finally, at the micrometer scale, humanoid micromachines "danced".

In concept validation, by designing the distribution and deformation direction of micro joints, a dual joint micro robotic arm can collect multiple micro particles in the same and opposite directions. In summary, the femtosecond laser two in one machining strategy can construct deformable micro joints in various local areas of three-dimensional microstructures, achieving various reconfigurable deformation modes.
Researchers have introduced that micro robotic arms with multiple deformation modes will exhibit broad application prospects in micro cargo collection, microfluidic manipulation, and cell manipulation.

Source: Micro and Nano Engineering Laboratory, University of Science and Technology of China