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
ReadNon-invasiveOptical
Optical sensing
Near-infrared light shone through the scalp measures changes in blood oxygenation that follow neural activity. Wearable, but slow. Higher-density and time-resolved systems sharpen the picture without changing what is measured.
Showing Optical sensing: Read, Non-invasive.
- Where it acts
- Light sources and detectors on the scalp
- Information flow
- Brain → light detectors
How far it has come
- As a clinical modality
- Human feasibilityA widely used research method in people. Not a routine clinical test of brain function.
- As a BCI application
- Research frontierUsed in research and early consumer devices. Too slow for fast control.
- Access
- Non-invasive
- Mechanism
- Optical
- Target
- Cortex
- Signal
- Haemodynamic response in the outer cortex
Characteristics · read interfaces
- Spatial resolutionCentimetre scale, superficial cortex
- Temporal resolutionSeconds
- Signal richnessIndirect: blood oxygenation, not electrical activity
- CoverageLarge areas of outer cortex
- InvasivenessNone
- Long-term stabilityModerate
Each track runs from low to high. A wide bar means the characteristic varies across implementations.
Strengths
- Wearable and tolerant of movement
- Insensitive to electrical noise
Trade-offs
- Too slow for fast control
- Reaches only the outer cortex
Common applications
- Cognitive and developmental research
- Brain-state monitoring
- Consumer wearables
Human evidence
Large research literature. As an interface, evidence is limited to slow, coarse signals.
What needs to happen next
Evidence that higher-density systems add usable information, not only sharper images.
- Same site, other direction
- Used by
- Axem Neurotechnology
- Patent activity
- 86 patent families name this interface, most often on optical 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