Smart Sutures Integrate Microfluidics and Nanosensors

New three-dimensional flexible platform makes it possible to envision its use for more complex shapes

"Smart" thread in vitro
Photo: Nano Lab/Tufts University
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The role of nanomaterials in textiles has evolved from comparatively simple hydrophobic materials to the creation of textile electrodes that leverage graphene and the weaving of nanowires into t-shirts to make them into supercapacitors.

Now researchers at Tufts University have taken nanomaterials for wearable systems to a new level with the development of a “smart” thread consisting of nanoscale sensors and microfluidics. The thread could be used in sutures, providing critical information in medical treatments.

In research described in the journal Microsystems and Nanoengineering, the Tufts researchers first took raw cotton thread and coated it with carbon nanotubes (CNTs) and other conductive materials. They then took this array of conductive threads and dipped them into physical and chemical sensing compounds.

To produce strain sensors, elastic threads (polyurethane threads) were coated with CNTs and a polymer. The polymer improved the mechanical integrity of the conductive layer and reduced the occurrence of delamination. For pH sensors, the working electrode was made from nano-infused threads coated with carbon and another type of conducting polymer that provided biocompatibility, high electrical conductivity, and superior stability in electrolytes.

The treated threads were all connected to wireless electronic circuitry so that when they were used as sutures, it was possible to collect data on tissue health.

When the tissue health measurements—including temperature, strain, and pressure—are combined with glucose and pH measurements, it becomes possible to determine how a wound is healing or whether an infection is developing. All this data is sent wirelessly to a computer.

“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,” said Sameer Sonkusale, a corresponding author on the paper and director of the interdisciplinary Nano Lab at the Tufts School of Engineering, in a press release.

While the initial research appears hopeful, the researchers do concede that more work needs to be done, most notably in the area of long-term biocompatibility.

Nonetheless, the work does represent a watershed moment in the development of substrate structures for implantable devices. Up till now, the structures have been limited to two dimensions, restricting their use only to flat tissue such as skin. However, this new three-dimensional flexible platform makes it possible to envision its use for more complex shapes such as those needed for fractures and orthopedic implants, which have complex 3-D structures.

Sonkusale added: “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.”

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IEEE Spectrum’s nanotechnology blog, featuring news and analysis about the development, applications, and future of science and technology at the nanoscale.