The latest study out of Denmark and the UK introduces the microchannel axialtrobe (mAxialtrobe). It’s a soft, multifunctional neural probe that brings together light delivery, electrical recording, and fluid channels—all packed into one needle-thin device.
This flexible probe moves with brain tissue. The goal? Cut down on chronic inflammation compared to stiff silicon implants, while still enabling optogenetic control, electrophysiology, and precise drug delivery along its shaft.
Overview of the mAxialtrobe technology
The mAxialtrobe uses custom-drawn optical fibers. These feature a 200-μm polycarbonate core, acrylic cladding, and eight tiny axial hollow microchannels just outside the core.
It carries light at 470 nm and 650 nm—wavelengths chosen to activate a bunch of opsins. The fiber stays under 0.5 mm thick, and it’s flexible enough to move with brain tissue. That’s supposed to reduce insertion damage and inflammation compared to the usual rigid implants.
Instead of the typical perpendicular tips, researchers cut the fiber tips at sharp angles. This angled-tip design changes how light spreads, helps reduce insertion trauma, and lets the probe shine light along its shaft in a more distributed way.
The microchannels run in parallel, offering a path for drugs or for threading in tiny recording or stimulation wires. So, you can deliver drugs, record signals, and trigger optogenetic effects all with one device.
Design and materials
The mAxialtrobe packs several features into a small form. Here are the main material and design highlights:
- 200-μm polycarbonate core with acrylic cladding to guide light efficiently
- Eight axial hollow microchannels just outside the core for fluid delivery or housing thin wires
- Overall thickness < 0.5 mm, keeping it flexible and compatible with brain tissue
- Acute-angle tips that shape light emission and lower insertion damage
- Light delivery at 470 nm and 650 nm for activating a wide set of opsins
The design also lets you deliver drugs through the hollow channels. You can fit in thin tungsten wires (about 20 μm) for recording and stimulation. This multi-modal approach could make surgeries simpler and boost data quality by disturbing less tissue.
Integrated functionality: light, fluids, and recording
By combining light delivery, fluid handling, and electrophysiology on one slim shaft, the mAxialtrobe allows simultaneous optogenetic activation, chemical modulation, and neural recording.
The microchannels give a direct path for drug delivery to specific brain areas. Meanwhile, 20-μm recording wires capture high-resolution electrophysiological signals.
The angled-tip design spreads light along the shank and helps minimize tissue damage during insertion. That could mean less chronic inflammation and gliosis over time.
For optogenetics, using 470 nm (blue) and 650 nm (red) light expands the range of tools you can use. This makes it easier to manipulate neural circuits with precision in live tissue.
Having optical, chemical, and electrical functions all in one biocompatible probe feels like a big step toward more flexible, less invasive brain interfaces.
In vivo performance in mice
In mouse experiments, the mAxialtrobe with electrodes spanning the hippocampus and cortex picked up strong neural signals. Researchers saw higher-amplitude theta waves—a well-known hippocampal rhythm—when they used the right bandpass filter.
They also managed to modulate neural activity with blue light by targeting specific opsins. This shows the device can do optogenetic stimulation in living animals. The multimodal setup opens doors for more detailed studies of circuit dynamics across different brain regions along the probe’s length.
Implications for neuroscience and clinical translation
The soft, polymer-based architecture aims to cut down on chronic tissue irritation. It also lets researchers probe multiple layers of neural tissue with just one device.
Right now, the team wants to push into real-time sensing experiments. They’re hoping to move this technology from animal models to actual clinical trials—maybe even to human applications someday.
If all goes well, the mAxialtrobe could give scientists a smoother way to combine optical control, chemical modulation, and electrophysiological readouts. That would be a big deal for both neuromodulation therapies and neuroscience research.
Here is the source article for this story: Improving Optical-Fiber Brain Probes