Researchers at the University of California, Irvine (UC Irvine) and Columbia University have developed a new sensor implant that uses soft, conformable materials embedded with transistors to monitor neurological functions. This biocompatible device adapts to a patient’s physiological changes over time, making it particularly useful for pediatric applications.
Researchers at UC Irvine have created a soft, conformable implant that measures neurological signals in patients’ developing brains. Seen here on the wing of a butterfly, this invention uses an organic polymer material that’s more compatible with sensitive living tissues than rigid, silicon-based medical devices. Image Credit: Duncan Wisniewski / University of California, Irvine
In a recent paper published in Nature Communications, UC Irvine scientists detailed the creation of complementary, ion-gated, organic electrochemical transistors (OECTs). These devices, designed with organic polymers, are more chemically, biologically, and electronically compatible with living tissues than traditional rigid, silicon-based technologies. The resulting medical device can function in sensitive parts of the body while conforming to organ structures as they grow.
Advanced electronics have been in development for several decades now, so there is a large repository of available circuit designs. The problem is that most of these transistor and amplifier technologies are not compatible with our physiology. For our innovation, we used organic polymer materials that are inherently closer to us biologically, and we designed it to interact with ions because the language of the brain and body is ionic, not electronic.
Dion Khodagholy, Study Co-Author and Henry Samueli Faculty Excellence Professor, University of California, Irvine
Traditional bioelectronics use complementary transistors made from different materials to handle various signal polarities. However, these rigid designs can be bulky, difficult to implement, and even toxic in sensitive areas. To overcome these limitations, the researchers developed asymmetric transistors that operate with a single, biocompatible material.
A transistor is like a simple valve that controls the flow of current. In our transistors, the physical process that controls this modulation is governed by the electrochemical doping and de-doping of the channel. By designing devices with asymmetrical contacts, we can control the doping location in the channel and switch the focus from negative potential to positive potential. This design approach allows us to make a complementary device using a single material.
Duncan Wisniewski, Study First Author, University of California, Irvine
He added that integrating transistors into a compact, single-polymer material significantly streamlines the fabrication process, making large-scale manufacturing feasible and opening possibilities for applying the technology to a wide range of biopotential processes beyond its initial neurological focus.
According to Khodagholy, Head of the UC Irvine Translational Neuroelectronics Laboratory, which recently relocated from Columbia University to Irvine, his team's work has the added advantage of scalability: “You can make different device sizes and still maintain this complementarity, and you can even change the material, which makes this innovation applicable in multiple situations.”
Another advantage emphasized in the Nature Communications paper is the device's ability to be implanted in a developing animal and adapt to changes in tissue structures as the organism grows—something that hard, silicon-based implants cannot achieve.
“This characteristic will make the device particularly useful in pediatric applications,” said Co-Author Jennifer Gelinas, UC Irvine Associate Professor of Anatomy and Neurobiology as well as pediatrics, who’s also a physician at Children’s Hospital of Orange County.
We demonstrated our ability to create robust complementary, integrated circuits that are capable of high-quality acquisition and processing of biological signals. Complementary, internal, ion-gated, organic electrochemical transistors will substantially broaden the application of bioelectronics to devices that have traditionally relied on bulky, non biocompatible components.
Dion Khodagholy, Study Co-Author and Henry Samueli Faculty Excellence Professor, University of California, Irvine
Claudia Cea, Liang Ma, Alexander Ranschaert, Onni Rauhala, and Zifang Zhao of Columbia University also contributed to this project alongside Khodagholy, Gelinas, and Wisniewski. The research was funded by the National Institutes of Health and the National Science Foundation.
Electrical engineering: Neuroelectronics for the brain
Video Credit: University of California, Irvine
Journal Reference
Wisniewski, D. J., et al. (2025) Spatial control of doping in conducting polymers enables complementary, conformable, implantable internal ion-gated organic electrochemical transistors. Nature Communications. doi.org/10.1038/s41467-024-55284-w.