Tin multielectrode fiber

The same 2015 MIT paper separately reports a polymer-metal recording fiber. A two-step thermal drawing process places tin electrodes within polyetherimide, with a sacrificial polyphenylsulfone outer layer. This is distinct from its conductive-polymer multimodal fiber.

Demonstrated structures

Published Figure 3a-c reports a 416 µm fiber before outer-cladding removal and an 85 µm structure after etching. The corresponding image shows seven tin electrodes. These dimensions apply to that demonstrated before/after structure, not every fiber or later variant.

Figure 3 also shows a preform with 36 electrodes and its resulting fiber, plus a separate nine-electrode structure surrounding a hollow channel. Those fabrication demonstrations do not establish 36 simultaneously recorded units or a 36-channel chronic mouse result. The hollow channel is described as filled with epoxy for cross-section polishing and microscopy; it is left open in the electrode-exposure image.

Recording and tissue response

The linked mouse study includes single-neuron recordings from the medial prefrontal cortex, separable units and multiple active recording electrodes. Optically evoked activity is also shown, but this recording-fiber entry does not inherit the integrated optical waveguide of the all-polymer architecture.

Figure 4 compares tissue markers surrounding these multielectrode probes and steel microwires from three days to three months after implantation, with n = 6 for each device and time point. Three-month histology is not a three-month electrical recording endpoint or proof of no tissue response.

Limits and model status

No clinical or human result is claimed. No complete 3D model is added: the accessible evidence gives selected cross-sections, but does not settle an entire implant, backend or exact geometry for every demonstrated variant. Individual electrode diameter and spacing values from unofficial full-text mirrors are deliberately not adopted.

Primary sources

• 2015 primary paper.
• Figure 3: etched geometry, recording and larger electrode-count variants.
• Figure 4: tissue-response comparison.
• Publisher supplement: two-step drawing, histology and explanted probes.

The inspected publisher page restricts the full main article. Abstract, published figure captions and the supplement support this entry; unavailable methods are not reconstructed.