From a tattoo that monitors our muscles to measuring oxygen levels in blood through skin, these non-invasive technologies in bio-medical engineering are advancing rapidly. Now, think of an electronic device embedded in sutures that can monitor the wound site and send the displayable feedback from the stitching area to your device using Bluetooth. Yup, that’s a stepping stone in the field of Flexible electronics and a team of researchers from Tufts University has accomplished that feat.
These “smart sutures” are made from different materials that can absorb and direct body fluids. Tuft’s researcher says that they have a suite of different threads, “cotton coated with carbon nanotubes, cotton coated with graphitic carbon, and threads electroplated with copper, platinum or silver.” He also mentioned that his research group has invented stretchable polyurethane threads with carbon nanotubes.
The sutures/ threads were stitched into both mice and also ex vivo (tissue sample in a petri dish outside living body). These threads were then able to collect the data from their environment and send feedback based on stress, temperature and pressure at the suture site. Additionally, the smart sutures also measures glucose and pH level in the wound which is important since these are the key indicators of wound healing and the presence or absence of infection.
This study published by Sonkusale and colleagues shows that the electrical resistance of polyurethane threads covered with carbon nanotubes changes with the strain induced on them. Therefore, by measuring the change in resistance, it can be determined how successful the wound-healing process is going and this indicator was used to monitor wound healing in mice. In the same way, the metallic threads changes depended on the temperature. So if the wound gives a high temperature, that is the indication of infection. This concept was introduced already by the research on temperature-sensing sutures.
The methodology in the paper is simple. The threads were attached to a small circuit-board, smaller than your smartphone screen, which was placed on mice skin. The board sent the data collected to a computer or even a smartphone using Bluetooth. Sonkusale (corresponding author for this study) is of the view that the circuit board could be even smaller in future and may shrink to the size of a single silicon chip.
“The ability to suture a thread-based diagnostic device intimately in a tissue or organ environment in three dimensions adds a unique feature that is not available with other flexible diagnostic platforms,” said Sonkusale. “We think thread-based devices could potentially be used as smart sutures for surgical implants, smart bandages to monitor wound healing, or integrated with textile or fabric as personalized health monitors and point-of-care diagnostics.”
The research paper by Tufts University researchers was published in journal Microsystems & Nanoengineering.