At the University of Delaware, Laure Kayser and her group have been developing soft electronic materials that can interface more naturally with the human body. Their latest work focuses on a hydrogel that moves between liquid and gel states depending on temperature. The team describes it as a reversible, conductive material that can be injected, shaped by the body, and later removed without surgery by cooling it back into a liquid. The results, add to a broader effort in bioelectronics to create materials that accommodate tissue rather than forcing the body to adapt to rigid devices.
Damani, V. S., Xie, X., Daso, R. E., Suman, K., Ghasemi, M., Xie, W., Wu, R., Wu, Y., Chao, C. L., Alberto, J. E., Lorch, C. M., Yang, A.-N., Nguyen, D. M., Shrestha, T., Otero, K., Lo, C.-Y., Pochan, D. J., Gomez, E. D., Rivnay, J., & Kayser, L. v. (2025). Thermo-reversible gelation of self-assembled conducting polymer colloids. Nature Communications, 16(1), 10879. https://doi.org/10.1038/s41467-025-66034-x
The material is based on linking two well-known polymers: the conductive polymer PEDOT:PSS and the thermoresponsive PNIPAM. While blends of these polymers have been explored before, the Delaware team created a block copolymer in which the two components are connected at the molecular level. This structural control appears to be central to the reversible behaviour. The hydrogel remains fluid below 35°C, then becomes a gel just above that point—close to body temperature. That transition makes it possible to inject the material as a liquid and have it solidify inside the body long enough to record nerve activity or deliver electrical stimulation.
Laure Kayser from University of Delaware stated,
“We’re hoping this material can be used as a platform for others. We’ve been shipping the material to labs across the world, who are excited to try it for their own applications.”
Experiments showed that one millilitre of the material could convert from liquid to gel in under a minute, and the process could be repeated at least ten times without major loss in conductivity. The gel also remained stable over long storage periods and liquefied again when cooled. According to the group, both ionic conductivity and electronic conductivity were maintained, which is an important distinction. Most conductive hydrogels carry ionic signals only, limiting their use in devices that need to bridge electronic hardware with biochemical processes.
To understand how the material organizes itself during heating and cooling, the Delaware team collaborated with researchers at Penn State and the University of Delaware’s own materials characterization facilities. Microscopy and scattering measurements showed that the block copolymer architecture enables orderly self-assembly, which appears necessary for the gel to maintain mechanical and electrical integrity throughout the transition cycle. Similar attempts using blends or less-controlled polymer structures did not demonstrate the same reversibility.
Biocompatibility studies were carried out in collaboration with Jonathan Rivnay’s group at Northwestern University. Tests in cultured cells and in rat models indicated that the material elicited minimal adverse reactions and was tolerated by surrounding tissue. The team then used small samples of the gel as electrodes on a human forearm. When the volunteer opened and closed a fist, the hydrogel recorded muscle signals with amplitudes far higher than those of standard commercial electrodes, suggesting the gel forms good contact with uneven or hair-covered skin.
Researchers in the field have been exploring soft electronic materials for several years, particularly those that can conform to tissues or be delivered through injection. Thermoresponsive hydrogels have been used in drug delivery and tissue engineering, but combining that behaviour with conductivity and reversibility is relatively new. The Delaware group notes that several labs have already requested samples to test in their own systems, ranging from neural probes to epidermal sensors.
The team has applied for a U.S. patent, and their next steps involve adapting the same chemistry for thin-film devices. They are developing organic electrochemical transistors based on the material, with the goal of building sensors that respond not only to biological signals but also to physiological changes such as temperature shifts. One example they mention is an implanted device that could detect local inflammation and trigger the release of an anti-inflammatory compound.
The work highlights how combining established polymers in new architectures can produce behaviours not easily achieved with standard formulations. For Kayser’s group, the reversible hydrogel represents a platform that may extend across several technologies. Whether used as an injectable, a temporary electrode, or a component in more complex biosensors, it offers a direction for building electronics that operate more comfortably at the interface between hardware and living tissue.
Adrian graduated with a Masters Degree (1st Class Honours) in Chemical Engineering from Chester University along with Harris. His master’s research aimed to develop a standardadised clean water oxygenation transfer procedure to test bubble diffusers that are currently used in the wastewater industry commercial market. He has also undergone placments in both US and China primarely focused within the R&D department and is an associate member of the Institute of Chemical Engineers (IChemE).
