A study led by Dartmouth Engineering professors demonstrates a new possible technique for connecting electronic implants with the surface of the brain, as well as a new method for ensuring safe, long-term medical access to the brain.
Alexander Boys and Katie Hixon combined their research areas of thin-film bioelectronics and regenerative tissue engineering to produce a neural device that promotes healing of the skull following implantation onto the brain. Their study is published in Advanced Materials Technologies and will be featured on the journal’s cover in March.
“Katie’s done a lot of work on bone regeneration in the skull, and my lab has built neural interfaces for various applications,” Boys says. “So we looked at solving two problems at once. One is developing a method for long-term access to larger regions of the brain, and the second is regrowing the skull over an implanted electronic device.”
The study demonstrates the feasibility of integrating the Boys Lab’s thin-film recording arrays with bone-regenerating cryogel scaffolds developed in Hixon’s lab. The scaffold consists of a degradable chitosan- and gelatin-based cryogel designed to provide an interconnected macroporous architecture that supports cell infiltration and tissue integration.
“We know my lab’s scaffold works to regrow bone, and we saw comparable bone formation between a cryogel-only scaffold and one with the integrated neural device,” Hixon says. “We also checked for any immune response over a period of about two weeks and saw none.”
The study’s first authors are Thayer School of Engineering PhD students Levi Olevsky, from Hixon’s lab, and Jonathan Pelusi, from Boys’ lab.
“In the beginning, we were just brainstorming how we can combine our two fields,” Olevsky says. “Combining bioelectronics with tissue regeneration was probably the coolest thing—seeing how you can bridge different areas of engineering.”
“Now,” Pelusi says, “we’re looking at ways to bridge the gap between the organic and the inorganic to create a direct interface between the two.”
To place any type of electronic brain implant—such as a stimulation device for Parkinson’s disease or epilepsy—or monitoring device, neurosurgeons need to remove a portion of the skull, Boys says.
“If you want to place a larger piece of hardware, you need to cut a bigger hole,” Boys explains. “What’s typically done for a larger monitoring device is to remove a piece of the skull, put the device onto the brain, take measurements, then remove the device and put the skull piece back on. This is due to a lack of methods to run the implant through the skull.”
“Or, perhaps the surgeon cuts a hole and, in order to maintain an implant’s placement, screws a metal plate back onto the skull,” he continues. “The patient then has metal protruding under the skin, which can cause problems. Our method would essentially regrow the region with natural bone while maintaining the implant placement.”
The innovation could remove the need for a lot of the closure methods, “like screws, that can erode your skin,” Hixon adds. “So it’s hopefully a faster recovery process and the implant can stay in longer.”
The research team says there also are several paths this work could take, including applications for brain-computer interfaces, pain monitoring in orthopedics, and increased understanding of fundamental bone physiology, “which is challenging to do in real time,” Boys says. “With these implants, anything that’s happening we can record as it happens.”
Adds Hixon, “I think long term, there’s a lot of things we could do. There’s work in electrical stimulation of bone that’s already used clinically, and it would only take a few tweaks to make the scaffold more conductive.”
“We could also add mineral to induce faster bone formation, or even look at healing of soft tissues,” she says. “That’s the cool thing about tissue engineering—you have base materials and methods that you can adapt with various cell types or additives for different uses.”
The team also is interested in investigating increased levels of integration for tissue-engineered bioelectronic devices. “This study shows that it works,” Boys says. “You can combine these types of systems, and they both work independently, and that’s good.”
That knowledge can serve as a basis for producing a more integrated system that’s not simply a combination. “We can advance and refine our approach of actually fabricating the scaffold around the device, to have a more seamless structure between the electronics and the tissue engineering components,” Boys says. “Or we can look at integrating with cells, for example, and growing them out to include an engineered cellular element in the system.”
Pelusi says that another already established approach would be to make it so that both the scaffold and the electronic device can be reabsorbed by the body. “So over a certain amount of time, you eliminate the need for an additional surgery to remove the device, which is huge,” he says.
Additional members of the research team are Amir Khan, a postdoctoral researcher in the Boys Lab; PhD candidate Peter Bertone and doctoral student Aleyna La Croix in the Hixon Lab; engineering sciences major Avery Jones ’26; and Caleb Stewart, a neurosurgery resident at Dartmouth Hitchcock Medical Center.
“We have a lot of overlap, and our students are closely integrated,” Hixon says. “They’re in classes together and have developed strong working relationships. We started a monthly meeting we call a ‘synergy session,’ where students share what they’ve been working on and present what’s happening in their labs, as well as identify areas for collaboration. Being so closely connected at Thayer—and being a smaller community—really helps foster that kind of interaction.”
The team also has collaborative relationships with DHMC and Geisel School of Medicine. “So for translation-oriented clinical and surgical work, we’ve got a pipeline to that,” Boys says.
“We’re all working to the strengths that Dartmouth has where there’s no real sense of competition between labs,” Pelusi says. “It’s this synergistic collaboration where you have labs excited to reach out to one another and combine fields to produce unique solutions.”
