Newly Designed Implantable Device Enables Long-Term Recording of Individual Neurons

January 26, 2024

This article has been looked over in accordance with Science X's editorial guidelines and principles. Certain qualities were given consideration while guaranteeing the credibility of the content:

• Fact-checked
• Peer-reviewed publication
• Trusted source
• Proofread

By Leah Burrows, Harvard John A. Paulson School of Engineering and Applied Sciences.

Gaining a deeper understanding of neural circuits requires chronic recording of single neuron activity across large populations in the brain. This is also crucial for brain-computer interfaces necessitating high-resolution electrophysiological data and for the development of innovative device-based therapies.

Yet, the longevity of recording or stimulation performance has been a constant tradeoff with the high resolution data that can be measured by an implanted device. Implants made of rigid silicon that houses multiple sensors are capable of collecting substantial data but have very limited longevity within the body. Conversely, smaller and flexible devices that are less invasive and can stay implanted for longer periods collect significantly less neural data.

An interdisciplinary group of researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), MIT, The University of Texas at Austin, and Axoft, Inc. recently fabricated a soft, implantable instrument outfitted with various sensors that can record single-neuron activity over several months.

The research was featured in Nature Nanotechnology.

'We've engineered more biocompatible brain-electronics interfaces that provide single-cell resolution than conventional materials,' said Paul Le Floch, the paper's primary author and a former graduate student in Jia Liu's lab, Assistant Professor of Bioengineering at SEAS. 'This work could significantly change how bioelectronics for neural recording and stimulation and brain-computer interfaces are designed.'

Currently, Le Floch is Axoft Inc.'s CEO, a company he co-founded with Liu and Tianyang Ye, a former graduate student and postdoctoral fellow at Harvard's Park Group, in 2021. The intellectual property of the research is protected and licensed for further development to Axoft by Harvard's Office of Technology Development.

To deal with this high-resolution data rate and implant longevity compromise, the team turned to fluorinated elastomers. This type of material including Teflon is not only resilient and stable in biofluids but it also demonstrates excellent long-term dielectric performance and compatibility to standard microfabrication techniques.

The researchers merged stacks of soft microelectrodes with these fluorinated dielectric elastomers to create a durable probe that is 10,000 times less rigid than traditional flexible probes made of polyimide or parylene C engineering plastics.

The team carried out in vivo demonstrations, amassing neural data from the brains and spinal cords of mice for several months.

'Our study underscores that novel elastomers for long-term-stable neural interfaces can indeed be designed by carefully adjusting various parameters,' says Liu, the paper's corresponding author. 'This opens up a range of new possibilities for designing neural interfaces.'

The in-depth study was co-authorized by researchers, all experts in their fields, including professors from SEAS-- Katia Bertoldi, Boris Kozinsky, and Zhigang Suo.

Designing novel neural interfaces is a multifaceted challenge that requires extensive knowledge in various fields including biology, electrical engineering, and materials, mechanical and chemical engineering,' said Le Floch.

Additional co-authors include Siyuan Zhao, Ren Liu, Nicola Molinari, Eder Medina, Hao Shen, Zheliang Wang, Junsoo Kim, Hao Sheng, Sebastian Partarrieu, Wenbo Wang, Chanan Sessler, Guogao Zhang, Hyunsu Park, Xian Gong, Andrew Spencer, Jongha Lee, Tianyang Ye, Xin Tang, Xiao Wang and Nanshu Lu.

Journal Information: Nature Nanotechnology

Provided by Harvard John A. Paulson School of Engineering and Applied Sciences.