Enhancing the specificity of optical probes

Optogenetics, devices that use light to alter the activity of neurons, offer a new way to probe and modulate the neural circuits involved in neurological diseases, such as Parkinson’s. The small size and complicated distribution of neurons requires spatially precise light stimulation. To replace traditional electrical and pharmacological light stimulation treatment methods, optogenetic devices must be safe and exhibit high spatial resolution.

Currently, the most common optogenetic devices are based on LED light. However, LED light has a diffuse emission, which lowers the spatial resolution of these devices. Zhou et al. designed and fabricated an optical probe based on an array of resonant-cavity light-emitting diodes (RCLEDs), which feature a narrower emission spectrum. Whereas traditional optogenetic devices are based on sapphire substrates, the authors integrated the RCLED array onto silicon, which has a higher thermal conductivity.

With these changes, the RCLED-based device demonstrated a smaller divergence angle, lower optical crosstalk, and less emission spectra shift than the LED-based devices. These improvements increased the spatial resolution of the optical probe, allowing precise neuron stimulation or modulation.

“The RCLEDs proposed in this work have offered a feasible technical solution for achieving lower optical crosstalk and more spectrally stable emission properties, both of which could meet the demands of precise neural regulation for bioprobes,” said author Binru Zhou. “This work provides a powerful protocol for studying specific neuronal functions.”

The RCLEDs used in this work emitted green light, but different wavelengths of light will enable researchers to study different types of neurons.

“Next, we will fabricate color-tunable RCLED devices on silicon platforms, which can be used to study the functions of multi-channel neurons,” Zhou said.

Source: “Linear flip-chipped resonant-cavity green µLEDs arrays for low crosstalk optogenetic probes with low damage,” by Binru Zhou, Guohong Wang, Xingfei Zhang, Yulong Tang, Xiaoping Zhou, Jin Lin, Jinpeng Huang, Zhicong Li, Ning Lv, Yuqiu Zhang, Yiyun Zhang, Xiaoyan Yi, Junxi Wang, and Jinmin Li, Applied Physics Reviews (2025). The article can be accessed at https://doi.org/10.1063/5.0237052 .