Tech Briefs

Threads sutured through layers of tissue gather data wirelessly in real time.

Implantable diagnostic devices and smart wearable systems that are capable of in situ sample collection and integration with the complex 3D structure of biological tissues offer significant opportunities for diagnosing and treating diseases. To that end, researchers led by Tufts University engineers have integrated nanoscale sensors, electronics, and microfluidics into threads that can be sutured through multiple layers of tissue to gather diagnostic data wirelessly in real time. The threads can range from simple cotton to sophisticated synthetics. The research suggests that the thread-based diagnostic platform could be an effective substrate for a new generation of implantable diagnostic devices and smart wearable systems.

Threads penetrate multiple layers of tissue to sample interstitial fluid and direct it to sensing threads that collect data, such as pH and glucose levels. Conductive threads then deliver the data to a flexible wireless transmitter sitting on top of the skin. The inset figure, upper left, shows liquid flowing in threads sutured into skin. (Credit: Nano Lab, Tufts University)

The researchers used a variety of conductive threads that were dipped in physical and chemical sensing compounds, and connected to wireless electronic circuitry. The result was a flexible platform that they sutured into tissue in rats, as well as in vitro. The threads collected data on tissue health (e.g. pressure, stress, strain, and temperature), pH, and glucose levels that can be used to determine such things as how a wound is healing, whether infection is emerging, or whether the body’s chemistry is out of balance. The results were transmitted wirelessly to a cell phone and computer (see figure).

The three-dimensional platform is able to conform to complex structures such as organs, wounds, or orthopedic implants. While more study is needed in a number of areas, including investigation of long-term biocompatibility, researchers said initial results raise the possibility of optimizing patient-specific treatments.

“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 Sameer Sonkusale, Ph.D., Director of the Interdisciplinary Nano Lab in the Department of Electrical and Computer Engineering at Tufts University’s School of Engineering. “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.”

Until now, the structure of substrates for implantable devices has essentially been two-dimensional, limiting their usefulness to flat tissue such as skin. Additionally, the materials in those substrates are expensive and require specialized processing.

“By contrast, thread is abundant, inexpensive, thin and flexible, and can be easily manipulated into complex shapes,” said Pooria Mostafalu, Ph.D., who was a doctoral student at Tufts when he worked on the project and is now a postdoctoral research fellow with the Harvard-MIT Division of Health Sciences and Technology, Brigham and Women’s Hospital, and the Wyss Institute for Biologically Inspired Engineering at Harvard University. “Additionally, analytes can be delivered directly to tissue by using thread’s natural wicking properties.”

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