|Schematic showing nonsurgical injection of mesh electronics into the vitreous body of the eye, allowing conformal coating of the mesh on the surface of retina for electrophysiological recording of individual retinal ganglion cells in live animals. Credit: Lieber Group, Harvard University. All rights reserved
Topics: Biology, Materials Science, Optics, Research
Mesh electronics, a macroporous network of components with mechanical properties similar to that of biological tissue, is a relatively new technology that can be used to probe activity in the brain. Now, researchers at Harvard University in the US have developed an injectable mesh that can record the neural activity of mouse eyes in vivo. The device, which does not interfere with eye movement or light-processing, could help neuroscientists study the fundamental properties of primary vision input retinal ganglion cells (RGCs) and how these cells connect with other vision-related brain regions for the first time. The work could also help in the development of retinal prosthetics for restoring vision through non-surgical procedures.
“Mesh electronics is a submicron-thick, large-area macroporous network,” explains team leader Charles Lieber. “We fabricate the meshes as flat 2D sheets using standard semiconductor photolithography-based techniques and suspend them (like a colloid) in aqueous solution. Our specific design, which we first reported on back in 2015, enables mesh electronics to be rolled up into a tubular structure and drawn into a syringe needle.”
On the scale of a single neuron
“We can deliver these structures into specific brain regions with a spatial precision of 20 microns (which is on the scale of a single neuron) using the controlled injection approach we developed. This allows us to control the rate at which we withdraw the needle during injection and means that the mesh structure remains fully extended in the dense tissue of the brain during injection and does not crumple.”
In their new work Lieber and colleagues “non-coaxially” injected the mesh electronics onto the highly curved retinal cup of the eye. As the structure unrolls it forms a stable recording interface to RGCs, which process visual information received by photoreceptors (rods and cones). The researchers then did a series of experiments.
Injectable mesh electronics opens up a new window into vision research Belle Dumé, Physics World