Nanophotonics: A High Bandwidth Optical Neural Interface
Light is a powerful tool for interrogating and manipulating biological systems, enabling targeted stimulation, sensing, and imaging. Optical methods such as optogenetics have transformed the study of neural circuits by making it possible to control neural activity using light. However, there remains a critical demand in research and medicine for miniaturized high resolution optical tools that can be embedded deep within biological systems like the brain. The brain poses particular challenges due to the sheer number of densely packed interconnected neurons and the strong tissue scattering and absorption of light. Nanophotonics, or chip-scale optical circuits, can enable unprecedented spatiotemporal resolution by leveraging nanoscale coherent control of a large set of optical channels within subwavelength waveguides with high speed reconfiguration capability, potential for integration with electronics, and low-cost scalable manufacturability. This potential high bandwidth optical neural interface can be as thin as a few neurons and have the ability to test spatial, temporal, and cell-type-specific aspects of neural encoding from cellular to system level within the brain.
I will present the first implantable nanophotonic probe for optogenetic stimulation and recording of neurons in live mice. To achieve this, we developed a reconfigurable visible nanophotonic platform based on phase-controlled silicon nitride interferometric waveguide structures that can control cellular-sized coherent emitters at blue wavelengths (peak of optogenetic actuators), far from traditional infrared wavelengths. This enabled a neural interface that can generate and read multi-neuron spike patterns deep within the brain with single-cell and sub-millisecond resolution, the highest resolution neuromodulation shown with an implantable probe.
In addition, I will highlight two building blocks for future nanophotonic stimulation and sensing devices that I developed using this platform: wide-angle chip-scale visible beam steering and multiplexing within a single waveguide by utilizing the transverse spatial degree-of-freedom of light. I will show how precise phase control and novel nanoscale photonic design of these building blocks has been applied to emerging high bandwidth optical applications like portable display technology and quantum optical systems. Finally, I will present a future outlook towards a new generation of implantable and wearable biomedical devices based on nanophotonic 3D light projection and sensing techniques including high-dimensional multiplexing, volumetric beam shaping, and quantum sensing.
Aseema Mohanty is currently a postdoctoral research scientist in Electrical Engineering at Columbia University in the Lipson Nanophotonics Group. Aseema received her Bachelor’s degree in Electrical Science and Engineering from the Massachusetts Institute of Technology and PhD in Electrical and Computer Engineering from Cornell University under the mentorship of Professor Michal Lipson. She was selected for a Lester B. Knight Graduate Fellowship, National Science Foundation Graduate Research Fellowship, and Rising Stars in EECS. Aseema’s research interests span the interdisciplinary fields of nanophotonics, biomedical devices, neuroscience, and quantum optics, and she welcomes every opportunity for exciting collaborations to translate knowledge across fields.
Host: Marc Baldo