At the University of Minnesota, researchers have developed a soft robotic system that can ‘grow’ like a plant. The mechanism allows it to travel through difficult-to-access areas, such as the tortuous gastrointestinal tract or vasculature. The system works by extruding a liquid through an opening in the device, and at the same time a photopolymerization process results in the rapid solidification of the liquid into a solid structure. The device illuminates the extruded liquid monomers, triggering the photopolymerization. This process mimics the way plants incrementally add material to their growing tips and root tips. The researchers hope that the technology could provide soft robots that can more easily travel to difficult-to-reach parts of the body.
Soft robots are making in-roads in the medical sphere, with their ability to interact with our soft tissues without the risk of abrasion and damage that come with more rigid devices. However, just being soft may not be enough to access everywhere in the body. Some spaces are difficult to travel to, and many of the ‘thoroughfares’ through our body, such as the gastrointestinal tract and our vasculature, are extremely windy, making it challenging to safely maneuver a robotic system through them.
These researchers took inspiration from the way that plants grow to develop a technique that can help a soft robot to navigate tight spaces. “We were really inspired by how plants and fungi grow,” said Matthew Hausladen, a researcher involved in the study. “We took the idea that plants and fungi add material at the end of their bodies, either at their root tips or at their new shoots, and we translated that to an engineering system.”
The device works by extruding a liquid out of a hole. As this occurs, the liquid monomer solution is activated using a light, triggering a photopolymerization process and resulting in a solid polymer ‘stalk’ that emerges from the back of the robot. This flexible and ever-growing stalk helps to push the robot through tight and winding spaces.
The researchers hope that this technique could lead to new types of soft robots that have unique advantages in accessing difficult-to-reach areas in the body.
Study in journal Proceedings of the National Academy of Sciences: Synthetic growth by self-lubricated photopolymerization and extrusion inspired by plants and fungi