Biodegradable electronics: Artificial synapse; microplastic problems; printing zinc circuits.
Researchers from Ulsan National Institute of Science and Technology (UNIST) designed a biodegradable, energy efficient artificial synapse that uses a layered structure made from naturally-derived polymers that break down naturally within 16 days in soil.
“The device is built like a tiny sandwich, with ion-active layers separated by an ion-binding layer made from cellulose acetate—derived from plant stems—and other layers sourced from shells and beans. When electricity is applied, sodium ions—similar to natural neurotransmitters—are released inside the device. These ions bind at the interfaces, a process called ion dipole coupling, which allows the synapse to hold onto some ions even after stimulation stops. This retention enables the device to produce cascade-like responses, supporting various forms of synaptic plasticity, including short-term and long-term memory,” explained JooHyeon Heo of UNIST in a press release.
The artificial synapse can hold its memory for nearly 6,000 seconds and uses just 0.85 femtojoules per signal. The team demonstrated the device in a simple robotic reflex system that triggers a robotic hand to move away from a hot object. [1]
Researchers from Northeastern University warn that materials used in transient electronics may not be as biodegradable as suggested. In particular, the polymer PEDOT:PSS was found to persist for more than eight years, and could form microplastic fragments when degrading. The team assessed a partly degradable pressure sensor and a fully degradable photodetector.
“You have to look at these materials carefully,” said Ravinder Dahiya, a professor of electrical and computer engineering at Northeastern University, in a statement. “Normally at the end of their life, electronics are dumped into the soil. When you put an electronic board in soil, we need to understand if the electronic board, during the degradation process, is enriching the soil or if the soil is unaffected. In some cases, degradation might damage the soil permanently, and that is a big environmental and health issue.”
In contrast to PEDOT:PSS, polymer materials such as cellulose and silk fibroin have high rates of degradation and release byproducts that are not harmful to the environment. The researchers are currently running a six-month degradation test to determine how long it takes certain transient electronics materials to fully degrade. [2]
Researchers from the University of Glasgow developed a method of printing zinc-based electronic circuits on biodegradable surfaces such as paper and bioplastics. The growth and transfer additive manufacturing process works by electroplating conductive bulk zinc onto a temporary carrier, which is then transferred to a biodegradable base. The method is capable of producing metal traces that are five microns wide.
The circuits performed comparably to traditional boards when used in devices including tactile sensors, LED counters, and temperature sensors, with performance remaining stable for more than a year. 99% of their materials can be disposed of through soil composting or by dissolving in chemicals like vinegar.
“One key aspect of our work is that almost any substrate material can be used in the process, ranging from paper and bioplastics for more realistic applications, to chocolate for tasty but probably not very practical demonstrations,” said Jeff Kettle, professor in the James Watt School of Engineering at the University of Glasgow, in a press release. “We are now exploring ways to adapt this technique to other fields such as mouldable electronics or biosensing, which could also benefit from a cheap and versatile way to make high quality circuits with low environmental footprints.” [3]
[1] Y. Chang, S. Na, Y.G. Ro, et al. Robust biodegradable synapse with sub-biological energy and extended memory for intelligent reflexive system. Nat Commun 16, 10610 (2025). https://doi.org/10.1038/s41467-025-66511-3
[2] S. Sandhu, R. Dahiya. End-of-Life usefulness of degradation by products from transient electronics. npj Flex Electron 9, 37 (2025). https://doi.org/10.1038/s41528-025-00411-w
[3] J.R. Harwell, T. Zhang, A. Rollo, et al. Additively manufacturing printed circuit boards with low waste footprint by transferring electroplated zinc tracks. Commun Mater 7, 17 (2026). https://doi.org/10.1038/s43246-025-01031-7
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