Plasmon-Coupled Photocapacitor Neuromodulators

Abstract

Efficient transduction of optical energy to bioelectrical stimuli is an important goal for effective communication with biological systems. For that plasmonics has significant potential via boosting the light-matter interactions. However, plasmonics has been primarily used for heat-induced cell stimulation due to membrane capacitance change (i.e., optocapacitance). Instead, here we demonstrate that plasmonic coupling to photocapacitor biointerfaces improves safe and efficacious neuromodulating displacement charges for an average of 185% in the entire visible spectrum while maintaining the Faradaic currents below 1%. Hot-electron injection dominantly leads the enhancement of displacement current at blue spectral window, and nanoantenna effect is mainly responsible for the improvement at redspectral region. The plasmonic photocapacitor facilitates wireless modulation of single cells at 3-orders of magnitude below the maximum retinal intensity levels corresponding to one of the most sensitive optoelectronic neural interfaces. This study introduces a new way of using plasmonics for safe and effective photostimulation of neurons and paves the way toward ultrasensitive plasmon-assisted neurostimulation devices.

Nanoengineering InP Quantum Dot-Based Photoactive Biointerfaces for Optical Control of Neurons

“…After mixing, the pH of aCSF solution was adjusted to 7.4 by adding a stoichiometric amount of NaOH. Light pulses were applied via Thorlabs M450LP1 LED with 445 nm nominal wavelength, and the LED spectrum is provided in our previous study (Melikov et al, 2020b). The blue LED was driven with Thorlabs DC2200 -High-Power 1-Channel LED Driver.…”

“…To investigate the internal operation of our devices, we conducted Mott-Schottky analysis and electrical impedance spectroscopy (EIS), which together allow us to investigate the charge-carrier dynamics and calculate the depletion width and minority carrier diffusion length (Melikov et al, 2020b). Mott-Schottky analysis can be applied to the devices that contain a semiconductor-semiconductor junction in which one semiconductor is much more doped than the other one (Chang et al, 2013).…”