KAIST Wireless Neural Chip Tracks Acetylcholine Changes in Minipig Brains After Alzheimer's Drug

In the prefrontal cortex of a minipig, a probe thinner than anything a fingertip would notice has been recording a chemical signal and sending it out over Bluetooth. The animal was given donepezil, a drug used to treat Alzheimer's disease, and the signal for acetylcholine rose, then slowly drifted back to where it began.

The device behind that observation comes from a joint team led by KAIST, which announced the work on October 27. Professor Kyung-In Jang of the Department of Mechanical Engineering led it, working with researchers at the Daegu Gyeongbuk Institute of Science and Technology (DGIST), the Korea Brain Research Institute (KBRI), and the Korea Research Institute of Bioscience and Biotechnology (KRIBB). The chip combines three things: a sensor for acetylcholine, a light-stimulation component, and miniaturized wireless measurement electronics.

Acetylcholine carries signals between nerve cells and matters for memory and learning. Donepezil works by inhibiting acetylcholinesterase, the enzyme that breaks acetylcholine down, so the neurotransmitter stays active longer. Following that effect in a specific brain region, as it happens, is the point of the chip. The prefrontal cortex, where the team placed it, is involved in judgment, attention, and memory. The result shows that a chemical response in one region can be tracked continuously from an external device.

The sensing layer is the core of the design. The researchers paired porous chitosan with ultrathin silver–platinum nanowires. The porous material offers a large surface for attaching the enzymes that detect acetylcholine, and the nanowires turn the hydrogen peroxide produced by the enzymatic reaction into an electrical signal.

To cut interference from other molecules, the team put an enzyme-coated electrode on one side of the probe and an enzyme-free electrode on the other. Comparing the two lets the system subtract what both pick up and isolate changes tied to acetylcholine. A small circuit processes the readings and passes them by Bluetooth to an outside device.

The chip can also stimulate neurons with light. In a separate experiment with transgenic mice, the team saw acetylcholine signals increase when a micro-LED built into the chip delivered light. KRIBB supplied the minipigs and surgical support, while KBRI supported the mouse surgeries and experiments.

The researchers see two uses. One is comparing neurotransmitter responses across drug doses and dosing intervals. The other is groundwork for closed-loop neural interfaces, in which a sensor detects the brain's response to stimulation and the intensity or timing of the next stimulation is adjusted. Putting sensing and light stimulation on one chip is meant to be a foundation for that.

The limits are stated plainly. The study measured neurotransmitter changes in animal brains. It did not show any therapeutic effect on Alzheimer's disease or any improvement in memory. Before human use, the technology needs further validation, including long-term safety and the stability of its measurements after implantation. Professor Jang said the work lays the groundwork for technologies that monitor the brain and adjust stimulation to its response.

Jieun Son, Saehyuck Oh, and Jeongdae Ha of DGIST were co-first authors, with Jang as corresponding author. The paper, titled "Implantable neural chip with electrochemical sensing and optogenetic stimulation for monitoring of cholinergic pharmacological responses," appeared October 14 in Device, a Cell Press journal (DOI 10.1016/j.device.2026.101329). The team plans to commercialize the technology through N-Side Inc., a faculty-founded startup whose CEO is Jang.