Over the last decade, small and flexible robots have demonstrated potential for minimally invasive medical procedures. These robots should be able to change their shapes in complex ways to adapt to various conditions in real-world settings, including unpredictable situations. Researchers have now developed new smart materials that serve as the foundation for the next wave of tiny medical robots. These minuscule robots, with a maximum length of just one centimeter, can perform tasks like biopsies or transporting cells and tissues in a minimally invasive manner. They are made of advanced, non-toxic, bio-compatible hydrogel composites, containing plant-derived cellulose nanoparticles. These robots are capable of navigating through tight, fluid-filled spaces like those found within the human body.

For the research, scientists at University of Waterloo (Waterloo, ON, Canada) adopted a holistic approach to designing these microrobots. They focused on every aspect, from conception to the material's synthesis, and even how to control their movements. The hydrogel material can change its shape when influenced by external chemicals. With the use of cellulose nanoparticles, the researchers can program these shape alterations, a critical factor in making functional soft robots. Another remarkable feature of this material is its self-healing property. This means the material can be cut and rejoined without the need for glue or other adhesives, allowing for a wide range of shapes suited to various medical procedures. In addition, the material can be magnetized, enabling easy control of the robot's movement within the human body. To demonstrate this, the team successfully maneuvered the tiny robot through a maze using a magnetic field. The next phase of their research aims to shrink these robots even further, down to sub-millimeter sizes.

"In my research group, we are bridging the old and new," said Shahsavan, director of the Smart Materials for Advanced Robotic Technologies (SMART-Lab). "We introduce emerging microrobots by leveraging traditional soft matter like hydrogels, liquid crystals, and colloids."

"Chemical engineers play a critical role in pushing the frontiers of medical microrobotics research," Shahsavan added. "Interestingly, tackling the many grand challenges in microrobotics 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." 

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