Until now, stitches and surgical sutures have acted matter-of-factly as medical tools — they close your wound until the incision or cut heals. Now, there's a new kind of suture on the horizon, one that comes fitted with micro-thin sensors to monitor the health of the wound, as well as deliver healing heat to the site on the fly.
Here, two kinds of ultra-thin temperature sensors are fitted to thin silicon membranes, which are wrapped around the polymer or silk suture. These nano sensors detect spikes in temperature around the wound, which could signal possible infection. If that is the case, then gold filaments also attached to the suture act as tiny little heaters when stimulated by a current, and help deliver healing heat to the wound.
If all this sounds like a lot to put on a tiny little suture, it is. It's completed on a scale that's only a few hundred nanometers thick. To keep the smart suture together, scientists use micro-thin films of silicon that are transferred to a polymer or silk strip. The electrodes and wires are placed on top of the silicon and the entire suture is covered in an epoxy coating.
The process is meant to keep the suture flexible enough to be sewn and tied in the body. The silicon that holds the sensors is the most brittle, so it is designed in a winding pattern to build in elasticity. Further, it's built like a sandwich — with the polymer or silk on the bottom and the epoxy coating on top so the greatest strain is on the outward facing materials.
John Rogers, professor of materials science and engineering at the University of Illinois at Urbana-Champaign, is responsible for creating the smart suture and he noted in the online journal Small that ensuring flexibility was one of the greatest challenges. But, it has been successfully trialed in rats without degrading the sensors. The next step is to test the sutures with the sensors active.
Rogers and his colleagues see a bright future for the smart sutures. The hope is they can be used to deliver drugs directly to a wound and be controlled wirelessly. That could lead to a day when your doctor could check your wound and prescribe drugs or painkillers for it via your existing sutures, and all from their smartphone or computer.