Synchron Chief Technology Officer Riki Banerjee [Photo courtesy of Synchron]
After 12 years in Medtronic’s neuromodulation operating unit and two years as R&D VP at Synchron, Riki Banerjee is the brain-computer interface (BCI) developer’s new chief technology officer.
More electrodes and thinner electrodes were always goals at Medtronic. But neuro device makers across the industry have faced the difficulties of developing chronic implants for stimulation, as well as designing interconnects to bridge the implants with the rest of the physical system.
“I think we’re on a good path to be successful” at Synchron, Banerjee said in an interview with Medical Design & Outsourcing in 2023 before she was promoted to CTO.
Related: Synchron’s plan to beat Neuralink in the neuroprosthetic BCI race
Synchron’s brain-computer interface (BCI) system uses the Stentrode brain implant to sense brain signals and relay them to a receiver implant in a patient’s chest. [Illustration courtesy of Synchron]
For one, while Synchron designed its BCI system for permanent implantation, it only senses brain signals and doesn’t stimulate. And Synchron believes it has solved the interconnect challenge with a lead that connects its electrode-stent Stentrode brain implant to the implantable receiver telemetry unit (IRTU) in a patient’s chest.
“I’ve been reflecting a lot on the process of developing a product when you have an implanted device, but also a complex system implanted device that has software, electrical, mechanical, all aspects of the tech stack,” she said. “You can’t really get true voice of customer until you have implants. You’ve got a little bit of a chicken-and-egg problem.”
So Synchron starts with a stent — or at least what looks like a stent. The Stentrode doesn’t need to prop the vessel open or resist external crushing forces, but uses the tubular shape to stay in place inside the blood vessel where it senses brain signals.
“It’s paramount that it’s safe. You can’t get approval to do anything until it’s safe, so foundationally it has to be safe, but it doesn’t have to be manufacturable,” she said. “You can hand build 10 units for clinical study, you can have a technician in Minnesota handbuilding something and as long as you can inspect quality and you can demonstrate that it’s safe.”
“Early on, when you’re doing a few patients, that’s the starting point,” she later continued. “And then [it’s] how do you make it manufacturable? … The early story of Synchron is really just taking existing stent technology and putting electrodes on it.”
A close-up of the Synchron Stentrode brain implant [Image courtesy of Synchron]
Instead of a laser-cut tube to provide physical support to the vessel like a traditional stent, Synchron manufactures its Stentrode implant with a thin-film process that prints layers of nitinol and layers of insulation contacts that serve as electrodes.
“It’s a sputtering technology on a silicon wafer, and the whole Stentrode is built up layer by layer using MEMS-based processing … and then the silicon wafer is like a carrier for it. So it’s released off of that, and it’s released in a flat format,” she said. “If you thought of the Stentrode, but unwrapped it and it’s flat and then it’s shaped around a mandrel, that’s how it gets its cylindrical shape. … It’s a very unique manufacturing process.”
For the lead between the Stentrode and the IRTU, Synchron’s tapped technology already in use for deep brain stimulation and other implant applications. Banerjee declined to say who manufactures that particular component.
With regards to outsourcing generally, Banerjee said she wants to keep key competencies internal but find opportunities to work with manufacturing partners. “There are a lot of great manufacturing partners out there. We’re pretty small, so definitely taking on more of the design aspect, but working closely moreso with external manufacturing partners.”
The plan is ultimately for all sterile, clinical product manufacturing to be done externally.
“We have a design facility, our verification testing labs, a lot of deep testing going on in our Brooklyn facility,” she said. “But formal manufacturing requires ISO certification, clean rooms, sterilization — it’s a whole different aspect of the business to take on. To me, it’s a stepwise approach and being smart about where we’re deepening our expertise.”
The fragility of thin-film devices will be a challenge when manufacturing at scale, she said.
“You have to manage handling very, very carefully at all aspects,” she said. “We are very carefully evaluating, and we have different suppliers that might do different pieces of it. When you’re shipping in between suppliers as the Stentrode is being assembled, that’s something you need to evaluate very carefully as each team handles it, making sure that you’ve done process development and evaluation and testing at each of those handling points.”
Asked for advice she might share with other device developers, Banerjee said she’s “always gravitated toward these very complex interdisciplinary spaces” and understanding the intersection of different disciplines, starting with user needs, through use conditions and all the way through manufacturing.
“So any mechanical implant, understanding those use conditions, which are: How is the physician handling it? How is it implanted in the body? How does it stay in place in the body? What are the chronic effects in the body? And really understanding that. And then the other side of it is, OK, so you can take those inputs and come up with designs, but the DFM (design for manufacturing) side of it — how do you make sure that design is manufacturable? Because if you end up in a lot of novel process development, that will inhibit your ability to scale and build product, too. Or a very novel supply chain, for example, could be very, very, very challenging.”
Opening the brain’s secret back door: A conversation with Synchron co-founder and CEO Dr. Tom Oxley