The tool, developed by researchers at the University of Illinois at Urbana-Champaign and collaborators, could overcome a key barrier to the clinical application of thin tissue grafts and flexible electronics, which have a host of applications for wound healing, regenerative medicine and biosensing.
“For the last few decades, cell or tissue sheets have been increasingly used to treat injured or diseased tissues. A crucial aspect of tissue transplantation surgery, such as corneal tissue transplantation surgery, is surgical gripping and safe transplantation of soft tissues. However, handling these living substances remains a grand challenge because they are fragile and easily crumple when picking them up from the culture media,” said study leader professor Hyunjoon Kong.
Current methods of transferring sheets involve growing them on a temperature-sensitive soft polymer that, once transferred, shrinks and releases the thin film. This process takes 30-60 minutes to transfer a single sheet, however, while requiring skilled technicians and running the risk of tearing or wrinkling, said Kong.
“During surgery, surgeons must minimise the risk of damage to soft tissues and transplant quickly, without contamination,” he added.
Seeking a way to quickly pick up and release thin, delicate sheets of cells or electronics without damaging them, the researchers turned to the animal kingdom for inspiration. Seeing the way an octopus or squid can pick up wet or dry objects of all shapes with small pressure changes in their muscle-powered suction cups, rather than a sticky chemical adhesive, gave the researchers an idea.
The team designed a manipulator made of a temperature-responsive layer of soft hydrogel attached to an electric heater. To pick up a thin sheet, the researchers gently heat the hydrogel to shrink it, then press it to the sheet and turn off the heat. The hydrogel expands slightly, creating suction with the soft tissue or flexible electronic film so it can be lifted and transferred. Then they gently place the thin film on the target and turn the heater back on, shrinking the hydrogel and releasing the sheet.
The entire process takes about 10 seconds, as shown in a YouTube demonstration.
The researchers hope to develop the manipulator by integrating sensors. “By integrating pressure sensors with the manipulator, it would be possible to monitor the deformation of target objects during contact and, in turn, adjust the suction force to a level at which materials retain their structural integrity and functionality,” said Kong. “By doing so, we can improve the safety and accuracy of handling these materials. In addition, we aim to examine therapeutic efficacy of cells and tissues transferred by the soft manipulator.”
Kong collaborated with researchers at Purdue University, the University of Illinois at Chicago, Chung-Ang University in South Korea and the Korea Advanced Institute for Science and Technology.
The research was published in Science Advances.
Want the best engineering stories delivered straight to your inbox? The Professional Engineering newsletter gives you vital updates on the most cutting-edge engineering and exciting new job opportunities. To sign up, click here.
Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.