Recording the activity of large populations of single neurons in the brain over long periods of time is important for our understanding of neural circuits, for enabling new medical device-based therapies, and for future, high-resolution brain-computer interfaces. Electrophysiological data.
But today there is a tradeoff between how high-resolution data an implanted device can measure and how long it can maintain recording or stimulating performance. Rigid, silicone implants with many sensors can collect a lot of information but cannot stay in the body for long. Flexible, small devices are less invasive and can linger in the brain but provide only a fraction of the available neural information.
Recently, Harvard John A. An interdisciplinary team of researchers from the Paulson School of Engineering and Applied Sciences (SEAS), in collaboration with the University of Texas at Austin, MIT and Axoft, Inc., developed a soft implantable device with dozens of sensors. which can record single-neuron activity in the brain stably for months.
The study was published Nature Nanotechnology.
We have developed brain-electronics interfaces with single-cell resolution that are more biocompatible than traditional materials. “This work could revolutionize the design of bioelectronics for neural recording and stimulation and for brain-computer interfaces.”
Paul Le Floch, first author of the paper and a former graduate student in Jia Liu’s lab, assistant professor of bioengineering at SEAS
Le Floch is currently the CEO of Axoft, Inc., a company founded in 2021 by Le Floch, Liu, and Tianyang Ye, a former graduate student and postdoctoral fellow at Harvard’s Park Group. Harvard’s Office of Technology Development protected the intellectual property associated with this research and licensed the technology to Axsoft for further development.
To overcome the tradeoff between high-resolution data rate and longevity, researchers turned to a group of materials known as fluorinated elastomers. Fluorinated materials such as Teflon are resilient, stable in organic fluids, have excellent long-term dielectric performance, and are compatible with standard microfabrication techniques.
The researchers combined these fluorinated dielectric elastomers with stacks of soft microelectrodes -; A total of 64 sensors -; to create a durable probe that is 10,000 times softer than conventional flexible probes made of engineering plastics such as polyamide or parylene C.
The team demonstrated the device aliveRecording neural data from rat brain and spinal cord over several months.
“Our research highlights that, by carefully engineering various factors, it is possible to design novel elastomers for long-term-stable neural interfaces,” said Liu, who is a corresponding author of the paper. “This research could expand the range of design possibilities for neural interfaces.”
The interdisciplinary research team also included SEAS professors Katia Bertoldi, Boris Kozinski, and Zhigang Su.
“Designing new neural probes and interfaces is a very interdisciplinary problem that requires expertise in biology, electrical engineering, materials science, mechanical and chemical engineering,” said Le Floch.
The study was co-authored by Siyuan Zhao, Ren Liu, Nicola Molinari, Eder Medina, Hao Shen, Zheliang Wang, Junsu Kim, Hao Sheng, Sebastian Partariu, Wenbo Wang, Chanan Sessler, Guogao Zhang, Hyunsu Park, Jian Gong, Andrew. Spencer, Zhongha Li, Tianyang Ye, Jin Tang, Xiao Wang, and Nanshu Lu.
The work was supported by the National Science Foundation through the Harvard University Materials Research Science and Engineering Center grant no. DMR-2011754.
Le Floch, P., etc. (2023). 3D spatiotemporally scalable in vivo neural probes based on fluorinated elastomers. Nature Nanotechnology. doi.org/10.1038/s41565-023-01545-6.