CAREER: Electro-optic Multiplexing for Massive Scaling of Neural Recording

Our perception of the outside world, cognition, and memory are all mediated through our brain. It is not yet completely known how processing in the brain gives rise to the richness of our experience. To understand how the activity of neurons contributes to the transformation of information in the brain, it is important to record neural signals across different areas of the brain with high resolution.

One of the widely used tools to record neuronal activity is a needle-shaped implantable device, called neural probe that penetrates through the tissue and has multiple recording sites to capture the activity of different neurons in the brain. Given the complexity of brain, the number of recording channels on the neural probe should be increased so that more signals can be captured from the central nervous system.

However, this comes at the cost of enlarging the implantable probe, causing severe damage to the brain tissue. In this project, the researchers aim to break this trade-off by designing a completely new class of ultrahigh density neural probes but with a very slim form factor to unravel the neural basis of brain function. This will be enabled by using light to carry the recorded signals from the brain.

This novel scalable technology offers a unique approach for high-density neural recording that can revolutionize the design of next generation brain-machine interfaces and also new therapeutics for mitigating brain disorders such as epilepsy, Parkinson’s and Alzheimer’s disease. This project provides a unique training opportunity for a new generation of students in the interdisciplinary field of neural engineering at the interface of nanotechnology, photonics, electronics and neuroscience.

The technical goal of this integrative research project is to design a novel ultrahigh density neural interface platform by directly recording the electrophysiology activity in the brain and encoding it into different optical wavelengths using the exquisite electro-optic properties of graphene. The optical signals will then be densely multiplexed using on-chip silicon photonic microresonators.

This method will massively scale up the number of neurons which can be simultaneously recorded and will provide unprecedented sensitivity and signal fidelity. This multidisciplinary research builds on a host of technological breakthroughs to leverage (i) the exceptional electro-optic properties of graphene for encoding electrophysiology signals onto optical signals and (ii) the narrowband resonance of high-quality photonic microresonators for on-chip wavelength-domain multiplexing of many recorded neural signals.

The proposed method enables simultaneous electro-optic neural recording from thousands of neurons without the need for any exogenous optical tags.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.