A single hair-thin fiber replaces three brain tools in mice tests

A team at the Technical University of Denmark has built a soft, hair-thin fiber that can record, stimulate, and deliver drugs to mouse brains from a single implant, [according to a peer-reviewed paper in Advanced Science](https://pmc.ncbi.nlm.nih.gov/articles/PMC13042959/).

The device, which the team calls the mAxialtrode, is a thermally drawn polymer fiber with electrodes and microfluidic channels spaced along its length. That pattern lets each function address a different layer of brain tissue, so one fiber reaches several depths at once.

In mouse tests, the team used the fiber to read electrical activity from multiple sites, trigger neurons with light, and inject drugs through the same shaft. A bioRxiv preprint describes the same design.

The shift from silicon probes matters because rigid implants tend to drift and trigger inflammation as the brain moves around them. The polymer version is soft enough, the authors report, to suppress that response and stay in place longer. Postdoc Kunyang Sui and Associate Professor Christos Markos at DTU led the work, per the university's news release.

The work is a research tool, not a therapy. The team's stated use cases are probing how signals travel during epilepsy, memory, and decision-making experiments in mice, with the DTU release framing localized drug delivery plus stimulation as a long-term therapeutic direction. No human or primate data is in the paper, and the result comes from a single group without independent replication.