NeuroPrint: Scientists Bioprint Brain Implants for Custom Neural Interfaces

Researchers have developed a new 3D printing technology that makes it possible to rapidly customize muscular and neural implants for monitoring and restoring motor and autonomic functions. The neural interfaces can be used to link brains to computers and could enable customized bioelectronics to treat patients with nervous system problems, like multiple sclerosis, epilepsy, Alzheimer’s, and Parkinson’s disease.

In a new study published in the journal Nature Biomedical Engineering, a team led by Ivan Minev, professor of Intelligent Healthcare Technologies at the University of Sheffield, England, and Pavel Musienko, head of the Neuroprosthetics Lab at Saint-Petersburg State University, in Russia, created a neural implant that was used to stimulate the spinal cord of animal models with spinal cord injuries. The technology now has the potential to develop new treatments for human patients with paralysis.

Electrode implants printed from platinum microparticles and silicone can be adapted to the anatomy of electrogenic tissues. Image courtesy of Saint-Petersburg State University/University of Sheffield.

This new patient-specific approach is possible due to NeuroPrint hybrid 3D printing technology developed at Saint-Petersburg State University. Using a 3DDiscovery bioprinter from Swiss 3D biotechnology company RegenHU, they created the geometry of the future implant made of silicone – which also serves as an insulating material. Then microparticles of platinum or another electrically conductive element of the implant are applied to the framework, and then the surface is activated by cold plasma.

The number and configuration of electrodes in the neural implant can be changed, producing devices for implantation in the tissue of the spinal cord, brain, or muscles. Furthermore, the average production time from project creation to prototyping can take just 24 hours. The capacity of hybrid printing to integrate soft materials and composites into the bioelectronic devices proved well adapted to various anatomical structures and experimental models to investigate, enable, and recover functions of the neuromuscular system.

Neuroscientists have already exploited the NeuroPrint technology to carry out research on various model objects. Through the monitoring and activation of neuronal pathways in the brain, spinal cord, and neuromuscular system of cats, rats, and zebrafish, the team showed that the printed bioelectronic interfaces permitted long-term integration and functional stability.

“We have tested our development in experiments on freely moving rats for chronic recording of the electrocortical signals of the cerebral cortex, that is a necessary element of the brain-computer interface,” said Musienko. “The experiments on paralysed animals have shown that electrical stimulation of neural networks effectively restores locomotor function. Thus, the NeuroPrint technology opens up new opportunities both for basic research into the central nervous system and for neuroprosthetics when people suffer from various diseases and injuries.”

According to the research, neuromuscular interfaces are required to translate bioelectronic technologies for application in clinical medicine. Neural interfaces establish communication between biological systems and electronic devices, which is why the possibility to interface with neural circuits has attracted a new generation of researchers and companies, like Neuralink, Elon Musk’s neural engineering company founded to make brain-machine interfaces to help individuals with paralysis. Scientific tool developer Qrons also announced research to develop innovative 3D printable biocompatible materials to treat penetrating brain injuries. While earlier this year, a team of researchers at MIT made implants that are not only soft enough for the human body but conductive enough to interact with the human brain.

Prototype soft bioelectronic implants for use as neuromuscular interfaces. Image courtesy of the University of Sheffield.

Linking the human brain to a computer via a neural interface is an ambition for many researchers. However, innovation in the field is hampered by the huge costs and long development time it takes to produce prototypes, which are needed for exploring new treatments. According to the University of Sheffield, the technology promises great potential to bring new medical treatments for injuries to the nervous system based on a fusion of biology and electronics. The vision relies on implants that can sense and supply tiny electrical impulses in the brain and the nervous system.

Through the new study, the team has shown how 3D printing technology can be used to make prototype implants much quicker and more cost-effectively in order to speed up research and development in the area. The team claims the implants can be easily adapted to target specific areas or problems within the nervous system.

Moreover, using the new technique, a neuroscientist could order a design which the engineering team can transform into a computer model that feeds instructions to the printer. The printer would then apply a palette of biocompatible, mechanically soft materials to realize the design. The implant can be quickly amended if changes are required, giving neuroscientists a quicker and cheaper way to test their ideas for potential treatments.

“The research we have started at TU Dresden (Dresden University of Technology) and continuing here at Sheffield has demonstrated how 3D printing can be harnessed to produce prototype implants at a speed and cost that hasn’t been done before, all whilst maintaining the standards needed to develop a useful device,” explained Minev. “The power of 3D printing means the prototype implants can be quickly changed and reproduced again as needed to help drive forward research and innovation in neural interfaces.”

The integrated platform for hybrid printing combines ink-jet dispensing of low-viscosity conductive inks, extrusion of insulating silicone pastes, and in situ surface activation via cold-air plasma. Image courtesy of Saint-Petersburg State University/University of Sheffield.

The researchers have shown that 3D printers can produce implants that can communicate with brains and nerves. Following this early work, they aim to demonstrate how the devices are robust when implanted for long periods. The researchers’ ambition, however, is to translate their work to the clinic and open up the possibilities of personalized medicine to neurosurgeons. Minev and Musienko expressed their desire to see the innovative neural implant technology in the operating theatre. Suggesting that perhaps in the future it will be possible to produce patient-specific neural implants right in the hospital, while the patient is being prepared for surgery.