Efficacy and usability of facial dry-printed electrodes for transocular stimulation

Transorbital electrical stimulation (TES) has emerged as a promising approach for eliciting visual percepts, or phosphenes, in both sighted and visually impaired individuals. However, the utility of these approaches is limited owing to cumbersome setups consisting of wired gel electrodes and the difficulty in optimizing stimulation paradigms. Overall, optimizing transorbital stimulation paradigms, remains a huge challenge, particularly regarding electrode type and waveform characteristics. In this study, we investigated whether the type of electrode (i.e. wet versus dry) affects the psychometric curve for phosphene detection. Our findings indicate that both electrode types yield comparable detection thresholds, suggesting that dry electrodes could offer a viable, practical alternative for TES without compromising efficacy, while dramatically enhancing usability. Building on this, we explored whether temporal interference (TI) stimulation, a technique leveraging high-frequency signals to create a low-frequency envelope at a targeted neural region, could enhance phosphene perception when optimized for the posterior retina. Our results demonstrate that TI stimulation significantly increases phosphene detection rates in sighted subjects, highlighting its potential to improve TES precision and effectiveness.Clinical relevanceThese findings have significant implications for the development of non-invasive neurostimulation technologies aimed at testing, restoring, or augmenting vision. The high performances of dry electrodes pave the way for more user-friendly, portable stimulation devices, reducing the reliance on cumbersome electrode preparations. Additionally, the enhancement of phosphene perception via TI suggests a pathway toward more selective, spatially targeted stimulation strategies, potentially refining TES for future clinical applications. Put together, these results contribute to the optimization of TES paradigms, bringing the technology closer to real-time, wearable neurostimulation solutions for visual rehabilitation and augmentation.