Researchers at three universities in Sweden have successfully grown electrodes in living tissue, using the body’s own molecules as triggers. The results, published in the journal Science, pave the way for forming fully integrated, biocompatible electronic circuits in living organisms.

By injecting a gel containing enzymes as the “assembly molecules,” the researchers were able to grow soft, conductive electrodes in the living tissue of zebrafish and medicinal leeches. In the future, it may be possible to fabricate fully integrated electronic circuits in living organisms, including humans, according to the researchers.

In experiments, the researchers achieved electrode formation in the brain, heart, and tail fins of zebrafish and around the nervous tissue of medicinal leeches. Contact with the body’s substances changed the structure of the gel and made it electrically conductive.

The animals were not harmed by the injected gel and were not affected by the electrode formation, which was accepted by the brain tissue and immune system, says Xenofon Strakosas, a researcher at the Laboratory for Organic Electronics and Lund University, and one of the study’s authors.

Body’s own tissues trigger formation of bio-friendly electrodes

With the new method, the body’s own molecules are enough to trigger the formation of electrodes. There is no need for genetic modification, implanted objects, or external signals, such as light or electrical energy, which have been required in previous experiments.

Linking electronics to biological tissue is important in combating diseases in the brain, developing future human-machine interfaces, and understanding complex biological functions, according to the researchers. Conventional bioelectronics systems are based on a fixed design that makes them difficult or impossible to combine with living biological signal systems.

Citation: Xenofon Strakosas et al. Metabolite-induced in vivo fabrication of substrate-free organic bioelectronics. Science. 23 Feb 2023 Vol 379, Issue 6634 pp. 795-802 https://www.science.org/doi/10.1126/science.adg4761

Abstract

Electronic devices implanted into a tissue close to neurons of interest are meant to exchange signals with the nervous system. Such bioelectronic devices not only facilitate the study of neural communication, they can also hijack neural circuitry in a therapeutic approach known as bioelectronic medicine. The success of these applications relies on the robustness of the implanted devices and their compatibility with the body. Conventional bioelectronic devices have solid substrates that carry conducting films. Their rigidity can damage soft tissues and reduce an implant’s long-term performance. On page 795 of this issue, Strakosas et al. (1) address the mechanical mismatch between soft and wet biological matter and solid-state electronics and describe an approach that generates electronics directly inside a tissue without a substrate, causing little damage to the tissue.

https://www.science.org/doi/10.1126/sciadv.aay5347?intcmp=trendmd-adv#

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