Sensor Patch Offers Non-Invasive Leak Diagnosis and Sealing of Post-Abdominal Surgery Sutures

Even today, these leaks pose a life-threatening complication. While the concept of sealing sutures in the abdominal cavity with plaster has been introduced in operating rooms, clinical success is not always guaranteed due to variations in tissue adhesion. The problem lies in the fact that the patches, made of protein-containing material, dissolve too quickly upon contact with digestive juices. Until now, healthcare professionals have had to rely on physical symptoms experienced by patients or delayed laboratory tests to identify leaking sutures, which often provide insufficient and delayed information. Now, a new and innovative solution in the form of a hydrogel-polymer patch addresses this challenge. This new patch prevents highly acidic digestive juices and bacteria-laden food residues from escaping the digestive tract, thus averting peritonitis or potentially life-threatening blood poisoning (sepsis). What sets this patch apart is the integration of non-electronic sensors that sound an "alarm" before digestive juices can leak into the abdominal cavity.

Researchers at Empa (Zurich, Switzerland) and ETH Zurich (Zurich, Switzerland) have developed a synthetic hydrogel material for the sensor patch, consisting of four different acrylic substances. To enable the hydrogel patch to detect leaks, the team collaborated with hospitals in Switzerland and international research partners to devise this innovative solution. The novel material possesses "vision" through its sensitive response to changes in pH value and the presence of specific proteins near the wound. Depending on the location of the leak, the reaction occurs within minutes or a few hours. The sensor patch detects escaping digestive fluid due to its composite structure. For instance, when acidic gastric juice interacts with the sensor material, gas bubbles emerge within the patch's matrix. These bubbles can then be visualized using ultrasound.

Moreover, these patches can be customized with sensors designed for various parts of the digestive tract. Additionally, if required, the patch can release medication like antibacterial agents. In the latest development, the researchers have further enhanced the patch's capabilities. The sensor response now includes a visible change during patient examinations using computed tomography (CT). If a leak is present at the surgical site, contrast deviations in ultrasound and CT images indicate its occurrence. The new material composition of the integrated sensor aids in detecting leaks, as it can be shaped into a form that stands out in imaging processes, thanks to an insoluble tantalum oxide compound. Upon contact with digestive fluid, the material changes its shape from circular to ring-shaped, for example.

According to the researchers, in the future, a sensor with a distinctive shape compared to anatomical structures in CT and ultrasound images could reduce ambiguity in diagnosing impending leaks. Moreover, the material possesses the necessary properties for wound closure, including a strong bond to tissue, the ability to form networks and stability against digestive fluids. As a result, this cost-effective and biocompatible "super glue," consisting predominantly of water, has the potential to not only reduce the risk of complications following abdominal surgery but also shorten hospital stays and save healthcare costs.

"Even today, such leaks are a life-threatening complication," explains Inge Herrmann, a researcher at Empa and professor of Nanoparticulate Systems at ETH Zurich. "The intestinal patch project is already attracting a great deal of interest from the medical profession."

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