Catalog specification sheet - Intracortical
Neurotrophic Electrode (Kennedy cone electrode)
Physical interfaceOptical micrograph
Neurotrophic cone-electrode assembly photographed under magnification; 2 mm scale retained.
Example assembly from the cited 2020 paper; experimental wire configurations differ.
Image credit & source
Gearing and Kennedy, Frontiers in Human Neuroscience (2020), Fig. 1A · Frontiers · Figure 1A · CC BY 4.0.
Photographic panel cropped from the original figure; resized and re-encoded. Original scale bars and annotations retained.
- Code
- ?3R
- Reviewed
- 2026-02-06
- Interface
- intracortical
- Evidence stage
- human
Independent, source-linked catalog sheet. Not a manufacturer-issued datasheet, regulatory decision or instructions for clinical use. Human evidence does not establish approval. Source-specific restrictions, conflicts and missing specifications are retained below.
Neurotrophic Electrode (Kennedy cone electrode)
The tables use the same field framework as the other implant-device sheets. Values belong to the named study or configuration. A blank cell means the reviewed sources do not establish a value, not that the device lacks that property.
Identity
| Field | Value and source scope |
|---|---|
| Device | Neurotrophic electrode, Kennedy cone family |
| Manufacturer | Neural Signals research program; 2008 assembly report |
| Interface class | Intracortical neurite-ingrowth electrode |
| Origin | Kennedy and collaborators; historical human recording program |
| First demonstrated | |
| First human implant | A human restoration report was published in 1998; earliest implantation date not established by this audit |
| Species studied | Human in reviewed 2008 and 2020 reports |
| Regulatory status | 2020 study reports FDA IDE G960032; not general commercial approval |
| Function | Recording for communication research |
| Target tissue | Motor speech cortex in the reviewed subject |
Geometry and architecture
| Field | Value and source scope |
|---|---|
| Interface type | Penetrating intracortical glass cone with ingrown neuropil |
| Array layout | Hollow glass cone containing gold wires |
| Electrode count | Three gold wires and two recording channels in 2020 subject 5; 2008 abstract describes a four-wire version, not one universal count |
| Pitch | Configuration dependent; wires offset inside cone, no uniform grid pitch |
| Electrode lengths | Cone length 1.5-2 mm, 2020 Methods |
| Shank width and thickness | Cone openings: 50 µm at deep end and 200-300 µm at upper end, 2020 Methods; wall thickness not reported |
| Tip and exposed site geometry | Hollow tip; closest wire end about 500 µm from deep opening in subject 5, 2020 |
| Contact coating | 99.9% gold wire, 2020 Methods; separate coating not reported |
| Insulation | Teflon-insulated 2 mil gold wires, glass cone and acrylic assembly, 2020 Methods |
| Insertion method | Surgical insertion into cortex; depth and angle not generalized across versions |
| Anchoring and fixation | Neurite ingrowth through cone; coiled flexible leads reduce strain, 2020 Methods |
Electrode and channel physics
| Field | Value and source scope |
|---|---|
| Exposed site area | |
| Electrode material | 99.9% gold wires inside glass cone, 2020 Methods |
| Impedance (with measurement frequency) | |
| Noise floor or SNR | 2020 subject 5: neural amplitude 12-80 µV peak-to-peak, system noise reported as 10 µV without a standardized RMS bandwidth qualification |
| Recording modality | Single-unit and continuous neural recordings, 2020 Methods |
| Sampling rate | Not given as a single hardware sampling rate; 2020 describes digital filtering and approximately 1 ms spike windows |
| Stimulation capability | Not used for stimulation in 2020 configuration |
| Charge injection limit | Not applicable to reviewed recording configuration |
| Reference and ground | Three wires feed two differential recording channels in 2020; pin-level reference assignment not reported |
Tissue interface and bioresponse
| Field | Value and source scope |
|---|---|
| Target tissue | Motor speech cortex |
| Insertion trauma and BBB disruption | Penetrating cortical placement; quantitative BBB injury not reported |
| Vascular disruption risk | |
| Micromotion sensitivity | Coiled leads intended to reduce strain at tip, 2020; quantified micromotion not reported |
| Gliosis and encapsulation | 2020 single-subject tip histology reports neurofilaments and absence of gliosis inside tip after 13 years; not a whole-cortex or cohort claim |
| Neuron loss near sites | |
| Foreign-body response mitigation | |
| Typical failure modes | 2020: handling-related trauma required three electronics replacements; electrode itself did not need replacement |
System architecture
| Field | Value and source scope |
|---|---|
| Onboard electronics | Subcutaneous skull-mounted differential amplifiers and FM transmitters, 2008/2020; not a percutaneous tether in this configuration |
| Data path | Cone wires to subcutaneous electronics, FM transmission through scalp to external receiver |
| Telemetry bandwidth | FM carrier 42 ± 8 MHz and amplifier bandpass 5-5,000 Hz in 2020; carrier range is not digital throughput |
| Sampling rate | Configuration dependent; exact rate not reported in reviewed Methods |
| Power | External induction coil powers implanted receiver coil; no battery in 2020 configuration |
| Thermal management | |
| Packaging and hermeticity | Elvax internal and Silastic external protection, 2020; hermetic qualification not reported |
| MRI compatibility | |
| Surgical complexity | Cortical insertion plus subcutaneous electronics fixed to skull with acrylic, 2020 |
| Output connectors | Internal miniature connector in 2008 assembly; external receiver captures FM signal |
Performance envelope
| Field | Value and source scope |
|---|---|
| Acute yield | |
| Chronic yield | |
| Stability over time | Functional neural activity at year nine, 2020 subject 5 report |
| Longevity | Recordings through 10 years in subject 5; histology after 13 years implanted. Implant duration is not recording duration |
| Revision and explant experience | Three electronics replacements due to handling trauma; electrode recovered postmortem, 2020 |
| Adverse events | Subject became too ill to record after year 10 owing to stroke progression; no device adverse-event rate established |
| Notable demonstrations | Functional single-unit conditioning at year nine; prior communication experiments cited in 2020 report |
Clinical and preclinical evidence
| Field | Value and source scope |
|---|---|
| Human subjects | 2020 histology: one locked-in subject, designated subject 5; designation is not an audited cohort size |
| Preclinical cohort | |
| Follow-up duration | |
| Indications | Locked-in syndrome after brainstem stroke; experimental communication |
| Trials and registries | FDA IDE G960032 reported in 2020; modern registry record not reported |
| Primary outcomes | Histological confirmation of myelinated filaments in cone and relation to decade-long recordings |
| Key limitations | Single-subject histology, hand-built version differences, few recording channels; not comparative lifetime evidence |
Engineering tradeoffs
| Field | Value and source scope |
|---|---|
| Strengths | Single-subject decade-long recording with postmortem ingrowth confirmation |
| Limitations | Few channels, hand assembly, and repeated electronics repair in reviewed case |
| Scaling constraints | Each cone requires implantation and wire routing; high-channel scaling not reported |
References
- Bartels et al. 2008. Neurotrophic electrode: method of assembly and implantation into human motor speech cortex. Assembly abstract; four-wire configuration.
- Kennedy et al. 2020. Histological Confirmation of Myelinated Neural Filaments Within the Tip of the Neurotrophic Electrode After a Decade of Neural Recordings. Subject 5 Methods and histology.
- Kennedy and Bakay 1998. Restoration of neural output from a paralyzed patient by a direct brain connection. Historical report; not used to infer earliest implant date.