Data Drop: Dr. Jiayi Zhang on Tellurium Nanowires and Broad-Spectrum Retinal Prostheses

In plain terms, what’s the big idea here - and why tellurium?

[Jiayi Zhang (JZ)]: Our team developed a subretinal nanoprosthesis using tellurium nanowire networks (TeNWNs), which offers several novel capabilities for vision restoration:

1. Broad-spectrum light sensitivity (visible to near-infrared-II): TeNWNs can convert both visible and NIR-II light (up to 1550 nm) into electrical signals. This significantly expands the spectral range usable for artificial vision.

2. Zero-bias photocurrent generation: TeNWNs generate photocurrents spontaneously, without requiring external power or bias. This mimics the function of natural photoreceptors and allows for fully passive operation.

3. High photocurrent density: We measured record-high photocurrent densities (up to 30 A/cm²), with broad sensitivity from visible through NIR-II wavelengths—well beyond what previous devices could achieve.

Tellurium was chosen because of its exceptional properties:

• High optical absorbance (up to 9% per layer).

• Built-in asymmetry in its crystal structure, with Sn substitutions and Te vacancies that drive spontaneous photocurrent generation.

• Flexibility in growth and tuning, allowing us to optimize morphology, defect properties, and bandgap for subretinal applications

These combined features make TeNWNs a powerful platform for light-to-electric signal transduction in retinal prosthetics.

You tested the device in both blind mice and macaques. What did each model reveal?

[JZ]: Our research in blind mice showed that TeNWNs could restore visual function both in the retina and cortex. Implanted mice exhibited improved pupillary light reflexes and performed significantly better in visually guided learning tasks, including water-reward associative learning and shape discrimination.

The macaque model allowed us to evaluate long-term biocompatibility and integration in an eye with closer anatomical and physiological similarity to humans. We observed good surgical outcomes and stable device performance over four months—crucial milestones for eventual human application.

What do we know about the spatial and temporal resolution of TeNWNs?

[JZ]: In terms of spatial resolution, we mapped retinal ganglion cell (RGC) receptive fields in blind mice implanted with TeNWNs. These receptive fields were comparable in size to those of normal mice, translating (by rough scaling) to an angular resolution of about 10-15 degrees in human terms—enough for detecting large objects, though not fine detail. Mice were able to distinguish geometric shapes under both white and NIR light with 62.3% accuracy.

For temporal resolution, TeNWN-mediated RGCs responded to flicker frequencies up to 5 Hz, albeit with delayed onset. This suggests that the device can support low-frequency dynamic visual tasks but may not capture rapid scene changes.

Stability and safety are essential for any implant. What do your in vivo results tell us about long-term durability?

[JZ]: We observed no signs of inflammation, rejection, retinal detachment, or neovascularization in the macaque model over four months. This indicates good tissue integration and short-to-mid-term biocompatibility.

However, open questions remain about longer-term mechanical and electrical stability. Factors such as eye movements, fluid exposure, or slow material degradation could impact performance. Encapsulation may extend device longevity, but risks compromising retinal interfacing. Monitoring for fibrosis or encapsulation over time will be critical in future studies.

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“If we can restore vision and extend it into new spectral ranges, are we merely treating blindness or enhancing human capability?”

How did you find your way into this project—and why optical materials?

[JZ]: Our lab has been working on vision restoration for over a decade. Many prostheses still rely on bulky glasses or external power sources, so we began exploring photoactive nanomaterials as an alternative; that is, ones that could restore light sensitivity without external hardware.

In 2018 and 2023, we demonstrated titanium dioxide nanowire prostheses that restored visible-light vision in rodents and primates. The next frontier was spectral expansion: could we restore not only normal vision, but extend it into NIR-II to capture information inaccessible to the naked eye?

That’s where TeNWNs came in. I encouraged the team to move beyond conventional device designs and push the material science to support this vision.

Looking ahead: is this headed for human trials, a startup, or something else?

[JZ]: We are cautiously optimistic about human translation. Our immediate focus is continued development and validation in the academic setting, but we are open to startup pathways as opportunities arise.

One question we’re thinking deeply about is ethics: if we can restore vision and extend it into new spectral ranges, are we merely treating blindness or enhancing human capability? That tension will likely shape how this technology evolves.