UC Santa Cruz engineers Ahsan Habib (left) and Ali Yanik have developed ultrasensitive nanoscale optical probes to monitor the bioelectric activity of neurons and other electrogenic cells. CREDIT: Carolyn Lagattuta
A new ultrasensitive nanoscale optical probe that can monitor the bioelectric activity of neurons (and other cells that generate electrical impulses) could help researchers better understand how neural circuits function at hitherto unexplored scales by measuring the activity of huge numbers of individual neurons at the same time. The device could also help in the development of high-bandwidth brain-machine interfaces in the future.
“Scientists have wanted to harness the unprecedented spatiotemporal resolution capability of light to detect electrophysiological signals from electrogenic cells (neurons and heart cells) for over 50 years,” says Ali Yanik of the University of California Santa Cruz, who led this new research effort. “This goal has remained elusive, however, for lack of electro-optical translators than can efficiently convert electrical activity into high photon-count optical signals.
“In this work, we have developed a novel electro-plasmonic nanoantenna that allows for extracellular (that is, non-invasive), high signal-to-noise ratio and real-time optical recording of electrophysiological signals for the first time.”
Poor spatial resolution and bio-incompatibility
Today, researchers monitor the electrical activity of neurons using microelectrode arrays, but these cannot simultaneously address large numbers of neurons. The technique also suffers from poor spatial resolution. The extremely limited bandwidth of the electronic wiring in these devices – created by the very nature of electrons – is a bottleneck too, explains Yanik.
“We have turned to photons for the same reason that the telecommunications industry moved to fibre-optics – because light offers a 109-fold enhanced multiplexing and information carrying capability. By converting bioelectric signals into photons, we are now able to transmit large-bandwidth neural activity optically.”
