Light-sensitive materials mimic synapses in the brain

An interdisciplinary research team has engineered a new class of organic photoelectrochemical transistors (OPECTs). These tiny devices can convert light into electrical signals and mimic the behavior of synapses in the brain. The research results have now been published in the research journal Advanced Science.

The team included Professor Francesca Santoro and Dr. Valeria Criscuolo from the Institute of Biological Information Processing—Bioelectronics at Forschungszentrum Jülich, in cooperation with colleagues from RWTH Aachen University—Professor Daniele Leonori and Junior Professor Giovanni Maria Piccini (now University of Modena and Reggio Emilia).

Our brains work by passing signals between nerve cells, adapting over time to learn and remember. Scientists are trying to recreate this kind of behavior in electronic devices, a field known as neuromorphic electronics. One way to do this is by developing materials that can “learn” in similar ways to how the brain does.

The team from Jülich and Aachen has taken an important step forward in this field. What makes their new technology special is that its properties can be precisely adjusted using chemistry. This means the material can be tailored to be particularly sensitive to light or able to transmit signals especially stably.

This opens up numerous potential applications: the platform could serve as an interface between technology and nerve cells, for example in visual prostheses or other medical devices. Highly sensitive optical sensors and novel brain–machine interfaces are also possible. Another advantage is that the components have low power consumption and can be adapted flexibly to different requirements.

In order for the device to be used later with real nerve cells or eye tissue, the material must be biocompatible—in other words, compatible with the human body—and function at body temperature. The researchers therefore use a special plastic called PEDOT:PSS, which has been modified with light-sensitive molecules. This material conducts electricity while remaining soft and flexible, making it suitable for use at the interface between electronics and biological tissue.

In the long term, this research could pave the way for new approaches to treating retinal diseases, such as age-related visual disorders. However, before it can be used in medicine, the technology must be tested carefully to ensure it is compatible with living tissue. To do so, the researchers carry out in vitro analyses—laboratory tests performed outside the body—and examine nerve tissue, among other things.