Stretchable catheter may detect dangerous arterial plaque before heart attacks strike

A new catheter under development at the USC Viterbi School of Engineering could give physicians a more detailed view of the plaques that accumulate inside arteries and trigger heart attacks or strokes. Led by Hangbo Zhao, an assistant professor of aerospace and mechanical engineering and biomedical engineering, the project aims to identify plaques that are biologically active and vulnerable to rupture—features that conventional medical imaging may not fully reveal. The research has received a National Institutes of Health Trailblazer Award from the National Institute of Biomedical Imaging and Bioengineering, a program designed to support innovative work by early-career investigators working across engineering, physical science and medicine.

Arterial plaque, or atherosclerotic plaque, forms when fatty deposits, cholesterol, inflammatory cells and other materials accumulate within the arterial wall. Some plaques remain relatively stable for years, while others develop internal characteristics that make them more likely to rupture. A rupture can expose thrombogenic material to the bloodstream, prompting the formation of a clot. If that clot blocks blood flow to the heart, it can cause a myocardial infarction; if it obstructs circulation to the brain, it can cause an ischemic stroke. The danger is that plaque size alone does not always indicate how unstable it is.

Zhao’s project, titled “High-Resolution 3D Electrical Impedance Mapping of Metabolically Active Plaques Using Multilayered Stretchable Liquid Metal Electronics,” is designed to provide information about plaque composition and metabolic activity. Instead of replacing ultrasound, computed tomography, magnetic resonance imaging or other established imaging methods, the proposed catheter would add electrical measurements that may distinguish tissue types and reveal biological changes associated with vulnerable plaque. The approach is based on electrical impedance, a property describing how strongly tissue resists or conducts an applied electrical signal.

Different biological tissues and chemical environments can exhibit different electrical responses. Lipid-rich regions, fibrous tissue, calcified areas and inflamed or metabolically active regions may therefore produce distinct impedance patterns. By collecting measurements across the inner surface of an artery and combining them spatially, the device could generate a high-resolution three-dimensional electrical map. Such a map may eventually help clinicians assess not only where plaque is located, but also whether its composition suggests an elevated risk of rupture.

The central engineering challenge is creating electronics that can function inside a blood vessel without behaving like a rigid foreign structure. Arteries are soft, curved and constantly moving as the heart pumps blood. They also vary in diameter and can be extremely narrow, making it difficult for conventional electronic components to maintain reliable contact with the vessel wall. Zhao’s research group addresses this problem through soft electronics and mechanics-driven manufacturing techniques that use liquid metal to form multilayered, stretchable circuits.

Liquid-metal conductors can carry electrical current while deforming substantially more than traditional metal traces. Integrated into elastic structures, they can bend, stretch and conform to complex biological surfaces. The challenge is to arrange multiple conductive layers, insulating materials and sensing elements with sufficient precision while preventing electrical short circuits or mechanical failure. Zhao’s group focuses on manufacturing strategies that preserve the electrical pathways as the device changes shape, allowing the sensing system to remain functional while it moves with the artery.

The electronics will be integrated onto a balloon catheter, a familiar medical device that can be guided through blood vessels in a compact form. After reaching a target location, the balloon can be gently inflated, expanding the sensing surface until it makes close and relatively uniform contact with the arterial wall. That contact is critical because electrical impedance measurements are sensitive to the distance and interface between the sensor and tissue. A more consistent interface could reduce measurement variability and allow the system to collect data around the circumference of the vessel rather than from a single point.

By combining conformable contact with multiple sensing elements, the catheter is intended to capture electrical information at many locations simultaneously or in rapid sequence. The resulting dataset could be processed into a three-dimensional representation of the artery’s internal surface and the plaque beneath it. In principle, this would give physicians a way to compare electrical signatures across a lesion, identify regions with unusual metabolic or compositional characteristics and integrate the information with images produced by existing diagnostic systems. The research is still at the development stage, and its clinical value will depend on how accurately the electrical signals correspond to plaque biology.

To evaluate that question, Zhao will collaborate with Tzung Hsiai, a professor of medicine and bioengineering at UCLA. The two research groups will test the technology in animal models of cardiovascular disease, where the catheter can be assessed under physiologically realistic conditions. These studies will examine whether the flexible device can be delivered safely, maintain contact with the vessel wall, produce stable measurements in a moving circulatory system and distinguish plaque features associated with disease progression. Results from such experiments will be necessary before the technology could be considered for human investigations.

The project reflects a broader movement toward medical devices that conform to the body rather than forcing biological tissue to accommodate rigid hardware. If successful, the stretchable liquid-metal catheter could provide physicians with an additional layer of information during cardiovascular procedures, potentially improving the ability to identify plaques that appear deceptively ordinary but contain dangerous biological activity. Zhao describes the Trailblazer Award as an opportunity to translate advances in soft-electronics manufacturing into surgical tools. The immediate goal is a high-resolution electrical map; the longer-term promise is a more personalized assessment of cardiovascular risk before a silent arterial lesion becomes a life-threatening emergency.

Web References: https://viterbi.usc.edu/directory/faculty/Zhao/Hangbo; https://www.nibib.nih.gov/funding/trailblazer-r21-awards; https://www.nibib.nih.gov/; https://sites.usc.edu/zhaogroup/; https://www.hsiailab.com/meetthelab.html