TechnologyHow do neural interfaces work?
How we interface with the nervous system
Every neural interface trades access, resolution and invasiveness against each other. This explorer places 32 of them on one map, by what they do and how far they have come, so that an EEG cap, a deep brain stimulator and an intracortical array can be read on the same terms.
BCI is evolving from decoding the nervous system to interacting with it.
- Reading
- Writing
- Closed loop
- Biohybrid
32 interfaces
Read
Bidirectional
Write
Non-invasive
Around the head
On the skin
Minimally invasive
Vessel or skull window
Invasive
Nerve or sense organ
On the cortex
In the cortex
Deep brain
Biohybrid · Adjacent frontier
Living neural tissue outside the body. Not an interface with a person.
Colour · function
- Read
- Write
- Bidirectional
- Biohybrid
Fill · maturity as a clinical modality
- Established
- Human feasibility
- Early human
- Preclinical
- Research frontier
- Adjacent frontier
WriteInvasiveElectrical
Retinal stimulation
An implant in the eye stimulates the retinal cells that survive when photoreceptors are lost, and the pattern travels on through the optic nerve. Photovoltaic implants are powered by the projected image itself.
Showing Retinal stimulation: Write, Invasive.
- Where it acts
- Under or on the retina
- Information flow
- Implant → retinal cells
How far it has come
- As a clinical modality
- Human feasibilityOne implant is authorised in Europe for geographic atrophy. Earlier devices left the market.
- As a BCI application
- Human feasibilityThe clearest current example of writing visual information into the nervous system.
- Access
- Invasive. Eye surgery, outside the skull.
- Mechanism
- Electrical
- Target
- Retina
- Signal
- Electrical stimulation of surviving retinal cells
Characteristics · write interfaces
- Spatial precisionEnough for letters and words, with magnification
- Temporal precisionTens of milliseconds
- TargetabilityA patch of central retina
- CoverageA small part of the visual field
- InvasivenessEye surgery
- ReversibilityThe implant is intended to stay
Each track runs from low to high. A wide bar means the characteristic varies across implementations.
Strengths
- Uses the eye's own optics and the remaining retinal circuits
- Photovoltaic implants need no cable through the wall of the eye
Trade-offs
- Needs surviving inner retina and an intact optic nerve
- Restores coarse, not natural, vision
Common applications
- Geographic atrophy from age-related macular degeneration
- Retinitis pigmentosa, with earlier devices
Human evidence
In a multicentre trial of a subretinal photovoltaic implant, 26 of 32 participants assessed at 12 months had a clinically meaningful gain in visual acuity (2025). Serious adverse events related to the procedure or device were reported.
What needs to happen next
Smaller pixels for sharper vision, longer follow-up, and use beyond one indication.
- Used by
- Science Corporation
- Clinical
- PRIMAvera
- Use cases
- See
- Patent activity
- 220 patent families name this interface, most often on peripheral interfaces, neural decoding, signal processing. The patent landscape
Descriptions, ranges and maturity levels are editorial analysis, kept qualitative where the literature does not support exact comparison across technologies. Specific devices differ.
All 32 interfaces as a table
| Interface | Function | Access | Mechanism | Target | Clinical modality | BCI application |
|---|---|---|---|---|---|---|
| Read | Non-invasive | Electrical | Cortex | Established | Human feasibility | |
| Read | Non-invasive | Magnetic | Cortex | Established | Research frontier | |
| Read | Non-invasive | Optical | Cortex | Human feasibility | Research frontier | |
| Read | Non-invasive | Electrical | Muscle / neuromotor | Established | Established | |
| Read | Minimally invasive | Electrical | Cortex | Human feasibility | Human feasibility | |
| Read | Minimally invasive | Acoustic | Cortex, Deep brain | Early human | Preclinical | |
| Read | Invasive | Electrical | Peripheral nerve, Muscle / neuromotor | Early human | Early human | |
| Read | Invasive | Electrical | Cortex | Established | Human feasibility | |
| Read | Invasive | Electrical | Cortex | Human feasibility | Human feasibility | |
| Read | Invasive | Electrical | Deep brain, Cortex | Established | Early human | |
| Write | Non-invasive | Magnetic | Cortex | Established | Research frontier | |
| Write | Non-invasive | Electrical | Cortex | Human feasibility | Research frontier | |
| Write | Non-invasive | Acoustic | Cortex, Deep brain | Early human | Research frontier | |
| Write | Invasive | Electrical | Peripheral nerve | Established | Early human | |
| Write | Invasive | Electrical | Retina | Human feasibility | Human feasibility | |
| Write | Invasive | Electrical | Cochlea | Established | Established | |
| Write | Invasive | Electrical | Brainstem | Established | Established | |
| Write | Invasive | Electrical | Cortex | Established | Early human | |
| Write | Invasive | Electrical | Cortex | Early human | Early human | |
| Write | Invasive | Optical, Molecular | Cortex, Deep brain, Retina | Early human | Preclinical | |
| Write | Invasive | Electrical | Deep brain | Established | Early human | |
| Bidirectional | Invasive | Electrical | Peripheral nerve, Muscle / neuromotor | Early human | Early human | |
| Bidirectional | Invasive | Electrical | Cortex | Established | Early human | |
| Bidirectional | Invasive | Electrical | Cortex, Deep brain | Established | Human feasibility | |
| Bidirectional | Invasive | Electrical | Cortex, Spinal cord | Early human | Early human | |
| Bidirectional | Invasive | Electrical | Cortex | Early human | Early human | |
| Bidirectional | Invasive | Electrical | Deep brain, Cortex | Established | Early human | |
| Bidirectional | Invasive | Electrical | Deep brain | Established | Human feasibility | |
| Biohybrid | Ex vivo | Electrical, Biological | Cultured neural tissue | Adjacent frontier | Adjacent frontier | |
| Biohybrid | Ex vivo | Electrical, Optical, Biological | Cultured neural tissue | Adjacent frontier | Adjacent frontier | |
| Biohybrid | Ex vivo | Biological, Electrical | Cultured neural tissue | Adjacent frontier | Adjacent frontier | |
| Biohybrid | Ex vivo | Biological, Electrical | Cultured neural tissue | Adjacent frontier | Adjacent frontier |
Use-case explorer
Start from what people want to do
Nine human goals. Each one connects the technology, the companies, the research, the studies and the tools behind it, and says plainly what is available today.
Decoding attempted speech or writing into text and voice.
Can someone who cannot speak hold a conversation again?
Research participants with paralysis have used implanted BCIs to produce text and synthesised voice from attempted speech. All such systems remain in early feasibility studies.
Latest milestoneA single surface implant decoded speech and upper-body gestures at the same time in three participants.
- Companies
- NeuralinkSynchronPrecision NeuroscienceParadromicsBlackrock NeurotechBrainGateStairMedNeuroXessNeuCyber NeuroTechABILITY NeurotechJiMEDg.tec medical engineeringArayaCognixion
- Research
- Simultaneous speech and gesture decoding for multimodal communication in paralysisAn Accurate and Rapidly Calibrating Speech NeuroprosthesisAn instantaneous voice-synthesis neuroprosthesisA high-performance speech neuroprosthesisA high-performance neuroprosthesis for speech decoding and avatar control+10 more
- Clinical
- VOICEConnect-OneBrainGate2BRAVOUNPCortiCom+3 more
- On the calendar
- BCI Meeting 2027
Why do such different devices exist for the same goal? Each trades signal quality against surgical access. Read the dossier