Catalog specification sheet - Peripheral nerve
Macro-Sieve Electrode
Physical interfaceOptical micrograph
Optical micrograph of the fabricated macro-sieve electrode and bonded micro-PCB; 2016 configuration.
Exact MacEwan et al. 2016 macro-sieve electrode in assigned catalog record. Panel crop, not a reconstruction. Include 600µm scale and region labels. License version to root-check through the article's actual CC BY link (4.0 expected).
Image credit & source
MacEwan, Zellmer, Wheeler, Burton & Moran, Frontiers in Neuroscience (2016), Figure 1B. DOI: 10.3389/fnins.2016.00557 · Frontiers · original figure · CC BY 4.0.
Photographic panel cropped from the original figure; resized and re-encoded. Original scale bars and annotations retained.
- Code
- ?1R
- Reviewed
- 2026-02-06
- Interface
- pni
- Evidence stage
- research
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.
Macro-sieve regenerative electrode with transit zones (MacEwan et al., 2016)
All rows follow the shared implant-device template. Measurements belong to the named study or configuration. A blank cell means the reviewed sources do not establish a value. Proposed use, terminal assays and continuously functioning implants are not treated as equivalent.
Identity
| Field | Value and source scope |
|---|---|
| Device | MacEwan 2016 macro-sieve electrode (MSE) |
| Manufacturer | Washington University research fabrication, MacEwan 2016 |
| Interface class | Regenerative peripheral nerve sieve |
| Origin | MacEwan, Zellmer, Wheeler, Burton and Moran team |
| First demonstrated | 2016 reviewed report; earliest prototype date not established |
| First human implant | Reviewed study uses rats |
| Species studied | Adult male Lewis rats |
| Regulatory status | Preclinical animal research |
| Function | Stimulation of regenerated sciatic nerve axons |
| Target tissue | Regenerated sciatic nerve through sieve transit zones |
Geometry and architecture
| Field | Value and source scope |
|---|---|
| Interface type | Regenerative sieve between transected nerve ends |
| Array layout | 2 mm diameter porous region; nine transit zones around eight electrode sites |
| Electrode count | Eight Pt-Ir sites; four curved around central zone, four straight on alternating spokes |
| Pitch | No uniform pitch reported; central transit hole about 600 µm diameter and each zone about 0.285 mm² |
| Electrode lengths | Not applicable to shanks; two 3 mm silicone conduit segments attached to sieve |
| Shank width and thickness | Polyimide wafer thickness not reported in audited article; assembly elastomer encapsulation 1-2 mm is not wafer thickness |
| Tip and exposed site geometry | Curved central sites about 33,000 µm²; straight peripheral sites about 24,000 µm² |
| Contact coating | Pt-Ir metallized/platinized sites as described by article; terminology preserved |
| Insulation | Polyimide base, medical epoxy at connections and elastomer encapsulation; silicone nerve conduits |
| Insertion method | Transect sciatic nerve, secure stumps in conduit assembly with about 4 mm gap |
| Anchoring and fixation | Nerve stumps secured inside conduits; connectors placed subcutaneously for terminal re-exposure |
Electrode and channel physics
| Field | Value and source scope |
|---|---|
| Exposed site area | About 33,000 µm² central curved and 24,000 µm² peripheral straight sites, Results |
| Electrode material | Pt-Ir/platinized active sites with gold traces on polyimide, Figures/Methods |
| Impedance (with measurement frequency) | At 1 kHz before implantation: 2.3-6.3 kΩ, mean 4.2 ± 0.9 kΩ; not chronic impedance |
| Noise floor or SNR | |
| Recording modality | Electrical stimulation through MSE; CNAP/EMG assay recordings use separate electrodes, not chronic MSE neural recording |
| Sampling rate | 40 kHz CNAP and 10 kHz EMG assay acquisition; not MSE onboard sampling specifications |
| Stimulation capability | Monopolar individual-site and simultaneous-site stimulation evoked reinnervated muscle force at three months |
| Charge injection limit | |
| Reference and ground | Monopolar assay configuration; exact assembly reference/ground pin map not reported |
Tissue interface and bioresponse
| Field | Value and source scope |
|---|---|
| Target tissue | Regenerating peripheral sciatic nerve |
| Insertion trauma and BBB disruption | BBB: not applicable; intentional sciatic nerve transection |
| Vascular disruption risk | Microvasculature seen crossing MSE; quantified vascular injury rate not reported |
| Micromotion sensitivity | Micro-PCB increases rigidity, Results; quantified micromotion not reported |
| Gliosis and encapsulation | Myelinated/unmyelinated fibers through transit zones; quantitative fibrosis burden not reported |
| Neuron loss near sites | |
| Foreign-body response mitigation | Large transit zones; GDNF tested versus saline and conduit controls, not universal coating efficacy |
| Typical failure modes | No assembly damage/failure observed through three months; longer-term failure rate not reported |
System architecture
| Field | Value and source scope |
|---|---|
| Onboard electronics | Passive electrode on micro-PCB; external stimulator for terminal evaluation |
| Data path | Gold traces to micro-PCB/microwires, subcutaneous Omnetics connector re-exposed at terminal experiment |
| Telemetry bandwidth | Not applicable; wired assay |
| Sampling rate | External assay-specific, no onboard ADC |
| Power | External test equipment |
| Thermal management | |
| Packaging and hermeticity | Epoxy EpoTek 730 protects connections; elastomer MDX4-4210 encapsulation; no hermetic certification |
| MRI compatibility | |
| Surgical complexity | Nerve transection, conduit assembly, lead routing and subcutaneous connector pocket |
| Output connectors | Female Omnetics 20-pin connector, Methods |
Performance envelope
| Field | Value and source scope |
|---|---|
| Acute yield | All tested metallized sites functional at implantation, Results; tested-site denominator not reported |
| Chronic yield | Assembly integrity maintained in all implanted animals through three months; not channel-by-channel chronic recording yield |
| Stability over time | Three-month terminal stimulation evidence; longitudinal recording stability not reported |
| Longevity | Three months observed, not maximum lifetime |
| Revision and explant experience | Terminal explant/histology, no clinical revision cohort |
| Adverse events | No assembly damage/failure reported in study; nerve injury inherent to model, not a general safety claim |
| Notable demonstrations | Individual MSE sites selectively recruited reinnervated muscles; all-site stimulation evoked force comparable to epineurial stimulation |
Clinical and preclinical evidence
| Field | Value and source scope |
|---|---|
| Human subjects | Not applicable to reviewed preclinical study |
| Preclinical cohort | 40 rats randomized to five groups of eight; two MSE groups of eight, two conduit groups and unoperated controls |
| Follow-up duration | Three months, terminal physiology; gait tracked at one, two and three months |
| Indications | Preclinical regenerative peripheral interface |
| Trials and registries | Animal research; human registry not applicable |
| Primary outcomes | Histomorphometry, CNAP, EMG, muscle force and behavior |
| Key limitations | Rat regenerative capacity and short follow-up limit human inference; terminal assay not continuous implanted recording |
Engineering tradeoffs
| Field | Value and source scope |
|---|---|
| Strengths | Large transit zones with regenerated axons and selective stimulation at three months |
| Limitations | Transection required; PCB stiffens thin sieve; no long-term human or recording evidence |
| Scaling constraints | Eight large sites access sectors rather than isolate each axon; density versus transit-area tradeoff |
References
- MacEwan et al. 2016. Regenerated Sciatic Nerve Axons Stimulated through a Chronically Implanted Macro-Sieve Electrode. Methods, Results and figures.