Chinese researchers create dancing microrobots using lasers

Scientists develop a new technique for using lasers to create "dancing" microrobots with movable joints that have a wide variety of applications.
Paul Ratner
Illustration of human-shaped robots moving their arms.
Researchers develop tiny "dancing" robots.
  • Chinese researchers use pulsed lasers to create "dancing" humanoid microrobots with a number of movable joints.
  • The scientists were inspired by the flexible joints of humans.
  • Possible applications of the developed technique include micro sensors, artificial muscles, wearable devices and a variety of others.

A team of researchers has come up with a method that utilizes femtosecond lasers to make micromachined joints, showcased by tiny “dancing” micro robots that look like humans.

Inspired by the flexible joints of humans, the scientists from the University of Science and Technology of China (USTC), of the Chinese Academy of Science, led by Prof. Wu Dong, proposed a two-in-one multi-material laser writing strategy that creates the joints from temperature-sensitive hydrogels as well as metal nanoparticles. 

What are femtosecond lasers? 

Femtosecond lasers are pulsed lasers that use short, intermittent irradiation. They feature the shortest pulse width, just one quadrillionth of a second (10-15 sec). Unlike a continuous wave laser, the material that’s affected by the pulse is instantly removed. 

The technique of femtosecond laser two-photon polymerization, a “true three-dimensional fabrication technique with nanoscale precision,” as the press release from USTC  describes it, has been widely used recently to create a number of functional microstructures. 

Such microstructures have been showing promise for applications in micro-nano optics, micro sensors, microelectromechanical systems. The study specifically mentions soft grippers, artificial muscles, and wearable devices as possibilities. The challenge lies in “integrating multiple microjoints into soft robots at the micrometer scale to achieve multi-deformation modalities,” as the scientists write in their paper, published in Nature Communications. 

One possibility would be to equip terrestrial robots with multiple shape memory alloy joints that can "realize linear/curvilinear crawling, walking, turning, and jumping by laser-inducing," as the study proposes. Another use would be to create flexible hands with multiple joints as an aid to disabled people. This would allow them to grip different kinds of objects.

Dancing microrobots

As the researchers explain in their study, “Flexible joints exist widely in natural organisms, and the cooperation between joints leads to elaborate movements and the realization of variable functions.” A typical human uses their multi-jointed limbs for walking, running or jumping. Their multi-jointed fingers allow them to manipulate objects. 

What the USTC researchers were able to achieve with their method is to build humanoid micro machines with a number of joints and multiple deformation modes — in other words, the ability to change their shape and size. The machines were made up of micro-joints, which were affected by multi-focal beams in 3D space. This allowed the machines to achieve different deformation modes that made it look like the microrobots were “dancing” at the micrometre scale.

The particulars of the method involved the femtosecond laser dual-function fabrication strategy that utilizes asymmetric two-photon polymerization to make hydrogel joints. Laser reduction was used to locally deposit silver nanoparticles (Ag NPs) into the joints. 

Insight from the researchers

Interesting Engineering reached out to the team from the University of Science and Technology of China for more insight on their accomplishment. In an email exchange, Xin Chen of USTC elaborated on why they chose to create dancing microrobots.

The researchers were inspired by the flexibility of human joints to construct micro-joints at the micrometer scale. “As humans can realize a variety of dancing movements through multiple joints, our microrobot also could reconstruct a variety of modalities (>10) using the collaboration between their microjoints, “shared Xin Chen, adding that “the dancing microrobots could highlight their reconfigurable multi-modality in an impressive way.”

Chinese researchers create dancing microrobots using lasers
Design and fabrication of light-triggered multi-joint microactuators by two-in-one laser printing.

On the question of how the femtosecond laser technique produces functional microstructures, Xin Chen pointed out that the fabrication of functional microstructures involves two steps. For the first step, a 3D hydrogel-based microstructure is created by the “asymmetrical direct femtosecond laser writing.” In the second step, femtosecond laser reduction selectively deposits silver nanoparticles on the surface of the microstructures. 

With regards to the possible applications of the technology, the representative of the research team shared that the so called two-in-one femtosecond laser processing technology could fabricate multi-modal microstructures. The scientists believe that the manufacturing technology they are developing could be used to create technical tools for the fields of microcargo manipulation, microfluidic chips, and microoptics. “Specifically, we could integrate these microactuators in a microfluidic chip, which in turn enables cell sorting and manipulation,” said Xin Chen.

What’s next for the research team? As stated in the correspondence, the current microstructure has limitations in its functionality, being a static microactuator. What the researchers are planning for their future work is to “develop a new generation of multi-joint microrobots that can move controllably in dynamic environments for performing more complex functions.” 

One example of this would be introducing magnetic materials into existing microactuators that would result in movable microrobot systems with multiple programmable modalities. In this way, magnetic fields would control locomotion, and light fields would control deformation. Another research goal for the team is to achieve “integrated control of multiple functional microstructures in the same system.” 

Xin Chen explained that an example of that would to “realize independent control of ten or even hundreds of microstructures at the same time, and thus realize multiple micro-object operations.”

Check out the full study “Light-triggered multi-joint microactuator fabricated by two-in-one femtosecond laser writing,”published in Nature Communications. 


Inspired by the flexible joints of humans, actuators containing soft joints have been developed for various applications, including soft grippers, artificial muscles, and wearable devices. However, integrating multiple microjoints into soft robots at the micrometer scale to achieve multi-deformation modalities remains challenging. Here, we propose a two-in-one femtosecond laser writing strategy to fabricate microjoints composed of hydrogel and metal nanoparticles, and develop multi-joint microactuators with multi-deformation modalities (>10), requiring short response time (30 ms) and low actuation power (<10 mW) to achieve deformation. Besides, independent joint deformation control and linkage of multi-joint deformation, including co-planar and spatial linkage, enables the microactuator to reconstruct a variety of complex human-like modalities. Finally, as a proof of concept, the collection of multiple microcargos at different locations is achieved by a double-joint micro robotic arm. Our microactuators with multiple modalities will bring many potential application opportunities in microcargo collection, microfluid operation, and cell manipulation.

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