Smart and advanced materials for future generations of soft medical microrobots

Plant-based materials give life to tiny soft robots that can potentially conduct medical procedures.


Hydrogels that respond to stimuli have attracted much interest as a diverse class of soft actuators. Responsive hydrogels with anisotropic characteristics and shape-change programmability offer various possibilities for creating soft robotics. In a new study, scientists report the synthesis of pH-responsive hydrogel nanocomposites with predetermined microstructural anisotropy, shape-transformation, and self-healing.

Scientists from the University of Waterloo have devised smart, advanced materials that will be used to develop future generations of soft medical microrobots.

These tiny robots can perform less invasive medical operations like cell and tissue transport and biopsy. They can transport delicate and light cargo, such as cells or tissues, to a desired location while moving through cramped and flooded environments, such as the human body.

The tiny soft robots are non-toxic and biocompatible, with a maximum length of one centimeter. The robots are constructed from cutting-edge hydrogel composites containing biodegradable cellulose nanoparticles from plants.

This study illustrates a comprehensive approach to the design, synthesis, manufacture, and manipulation of microrobots under the direction of Hamed Shahsavan, a Department of Chemical Engineering professor. When subjected to external chemical stimulus, the hydrogel employed in this work adapts to the environmental change. Researchers can now program such shape-change, which is essential for creating functional soft robots, by orienting cellulose nanoparticles in any direction.

Another distinguishing feature of this advanced smart material is its capacity for self-healing, which enables a wide variety of robot shapes to be programmed. Researchers can cut the material and put it back together to create various forms for various operations without using glue or other adhesives. 

The substance can be further altered with a magnetic to make it easier for soft robots to navigate the human body. Researchers used a magnetic field to direct the tiny robot’s movement through a maze as proof of concept for how the robot would navigate through the body.

Hamed Shahsavan, a Department of Chemical Engineering professor, said“Chemical engineers play a critical role in pushing the frontiers of medical microrobotics research. Interestingly, tackling the many grand challenges in micro-robotics requires the skillset and knowledge chemical engineers possess, including heat and mass transfer, fluid mechanics, reaction engineering, polymers, soft matter science, and biochemical systems. So, we are uniquely positioned to introduce innovative avenues in this emerging field.”

The next step in this research is to scale the robot down to submillimeter scales.

Journal Reference:

  1. Nasseri, R., Bouzari, N., Huang, J. et al. Programmable nanocomposites of cellulose nanocrystals and zwitterionic hydrogels for soft robotics. Nat Commun 14, 6108 (2023). DOI: 10.1038/s41467-023-41874-7
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