10/1/2025 Michael O'Boyle
Researchers, led by Assistant Professor Yuecheng "Peter" Zhou during his postdoctoral work at Stanford University, demonstrated how to optimize electrochromic polymers — materials that change color in response to voltage — as non-invasive sensors for recording electrical activity in biological systems. By tailoring the polymer chemistry to specific systems like cardiac tissue and neurons, the team achieved sensitivity matching conventional electrode sensors without damaging cells. Zhou is continuing to develop these polymer-based recording methods for practical use in biological research.
Written by Michael O'Boyle
Electrochromic polymers change color when exposed to electricity. Researchers show how to optimize them for recording bioelectric signals.
Electrochromic polymers change color in response to applied voltage, making them strong candidates for studying electrical activity in biological systems without invasive sensor insertion. A new study demonstrates how individual polymers can be engineered to maximize sensitivity to specific systems.
The research was conducted by Yuecheng "Peter" Zhou – at the time a postdoctoral researcher at Stanford University and currently a materials science and engineering professor in The Grainger College of Engineering at the University of Illinois Urbana-Champaign – and was recently published in Nature Communications. By exploring three electrochromic polymers acting on cardiac and neural systems, he and his colleagues demonstrated that a sensitivity of 3.3 microvolts could be achieved, putting the sensitivity on par with conventional sensors.
“In this study, we investigated how the biology and polymer chemistry synergically influence the recording sensitivity,” Zhou said. “In my current group at Illinois, we’re tailoring the properties of electrochromic polymers to specific biological systems to achieve the highest recording sensitivity to bioelectric signals.”
Electrical activity provides important information about biological processes such as neurological and muscular activity. Standard methods for observing these processes require inserting probes into cells that could irreparably damage the cells and limit the recording duration.
Electrochromic polymers have emerged as a desirable alternative. Their color changes and can be used to observe bioelectricity over time when in physical contact with the cells. The main challenge in implementing such polymers as sensors is tuning their sensitivity in a way that matches the probing light’s wavelength.
Zhou and his colleagues studied how polymers with different chemistries interact with the specifics of the biology by considering three dioxythiophene-based conjugated polymers and three biological systems: isolated rat hearts, human-induced pluripotent stem cell-derived cardiomyocytes, and cultured rat hippocampal neurons. They found that adjusting the polymer backbone and sidechain chemistry significantly improved detection sensitivity.
“This creates a feedback loop,” Zhou said. “You start with a biological system. You perform recording experiments to see how the biology interacts with the polymer. Then, you reverse design the polymer to adapt it to the biological system. You then iterate until you have an optimal polymer.”
Zhou’s research group in Illinois Grainger Engineering is developing new tools grounded in materials science that would allow researchers to synthesize and optimize electrochromic polymers for specific biological systems under consideration. In addition, they are exploring how to improve the time and spatial resolution of such methods so they can map electrical signals in more detail.
“I want to develop this technique into new directions here at Illinois,” Zhou said. “That means going beyond the fundamental chemistry of these polymers and viewing them with a materials science mindset. We don’t just want to understand them. We also want to engineer working methods for practicing researchers.”
This study’s other contributors are Erica Liu, Pengwei Sun, Yang Yang, Ching-Ting Tsai, Tomasz Zaluska, Wei Zhang, and Bianxiao Cui of Stanford University; Anna Österholm, Austin Jones, and John Reyonolds of the Georgia Institute of Technology; and Holger Müller of the University of California, Berkeley.
The article, “Ultrasensitive label-free optical recording of bioelectric potentials using dioxythiophene-based electrochromic polymers,” is available online. DOI: 10.1038/s41467-025-61708-y
Support was provided by the National Institutes of Health and the Office of Naval Research.
Illinois Grainger Engineering Affiliations
Yuecheng "Peter" Zhou is an Illinois Grainger Engineering assistant professor of materials science and engineering in the Department of Materials Science and Engineering. He is also affiliated with the Department of Bioengineering. He is a faculty member of the Materials Research Laboratory and the Beckman Institute for Advanced Science and Technology.