Interview: Flexible Rubber and Plastic Brain Implants

John Rogers, University of Illinois, explains the work he is conducting with Dr. Brian Litt, associate professor of bioengineering and neurology, University of Pennsylvania, in reducing the size and increasing the effectiveness of brain implants.

Listen to the podcast of this interview.

Could you explain the work you’re doing with Dr. Litt on brain implants?

We’re trying to develop technologies for monitoring and stimulating the brain that involve ultra-thin and conformal electrodes and electronics that kind of laminate directly on the surface of the brain and have sufficient flexibility that they can follow the contours and folds associated with the brain surface. So, we’re trying to develop technologies then that enable fundamentally new capabilities in resolution speed and fidelity of measurement. I think that kind of technology can have multiple use scenarios; the one we’re focused primarily on with Dr. Litt is in the diagnosis and treatment of epilepsy because he’s an expert in that area.

How did you arrive at flexible plastic and rubber?

It’s interesting; my group here at U of Illinois is a material science group. We’re interested in unusual electronic materials and have historically been pursuing classes of materials and devices that enable flexible electronics for consumer applications, like paper light displays, roll-up cell phones, that kind of thing. It was really as a result of a seminar I gave at the University of Pennsylvania on those types of technologies that stimulated our interactions with Brian’s group, which was at that time interested in exploring opportunities of using that kind of electronics, not in consumer devices, but in bio-integrated devices, such as those that I just mentioned, for integration with the brain. So, that really was an appealing opportunity for applying our knowledge in flexible semi-conductor devices to an area that has greater societal benefits, quite frankly, than a new type of cell phone or a new type of e-book. It’s really led to a dramatic shift in our focus away from consumer widgets to devices that can have a real benefit on human health, and so that’s, kind of, the trajectory. Started in consumer electronics and has now refocused itself on devices for advanced healthcare. There is a whole set of interesting materials challenges that go along with integrating devices with the human body. For example, these brain monitors might have to be able to operate under salt water, because in their clinical use, they’re completely bathed in biofluid. Designing a circuit that can accommodate that kind of fluid immersion is tough, and that’s one you don’t typically have to worry about too much with consumer electronic devices. So, there is a whole host of interesting material science problems of fundamental nature but applied in an area that I think stands to offer some significant societal benefits in a way that consumer electronic devices probably can’t.

What do flexible plastic and rubber offer that other materials don’t?

If you look at conventional semi-conductor technologies, they’re typically built on the surfaces of semi-conductor wafers, like a silicone wafer. That kind of platform is great for lots of device applications, but it’s inherently a flat, rigid, and brittle type of support. So, the electronics that are formed on those wafers have those attributes. If you look at the human body, it’s much different; it’s curved, and elastic, and soft, and, so, much different than a semi-conductor wafer. To achieve a kind of integration between the body and electronics requires completely new forms and mechanics in the electronics. So, we’ve been focused on new materials and new structures of old materials that can kind of bridge that gap, that can allow one to make high-performance electronics, like you can currently achieve on silicone wafers, but in a format that is soft, and shaped, and mechanically matched to the tissue of the body, say the brain. That’s a challenge, and it’s required a series of different ideas, different mechanical designs, layouts, different materials, different forms to enable that outcome. But we have been working on that problem for 6, almost 7, years and have a set of technologies that really do allow you to integrate electronics with the body in ways that were previously inconceivable. I think it’s going to bring a whole set of new and powerful capabilities to diagnostics, monitors, even therapeutic and surgical devices that will have wide-ranging benefits.

Other than epilepsy, what diseases or conditions can this technology be used for?

Another area of the body that we’re working on is the heart. We’ve worked with Brian and his colleagues in cardiology, and also researchers at the Sarver Heart Institute in Arizona to develop devices that enable a diagnostic and therapeutic capability for treating arrhythmias. You would like an ability to map out electrical activity associated with beating of the heart to identify aberrant tissue that is causing the arrhythmia. And once you have identified where that tissue is located, you would like to destroy it, either through an ablation or a resection process. So, we have built devices, and published papers on devices, that can do that kind of mapping; it’s very high spatial and temporal fidelity to identify those aberrant regions, and in unpublished work, we have similar devices that can take the next step and ablate them, to destroy them and eliminate their adverse effects on the beating of the heart. The brain and heart are the two areas where we’re currently focused, but that’s not because they’re aren’t other opportunities; it’s just because I have a finite group and a finite number of people to work on these problems, and we’ve chosen those two because we think the potential for impact is high and we have excellent collaborators in those areas.

How far are the brain implants from being approved for regular use?

I’m not intimately familiar with the FDA process. I can say, though, that these devices—both the ones designed for the heart and the brain—are used as temporary devices that go in and are used during a surgical procedure. So, they don’t have to face the more stringent hurdles that are associated with a drug or a long-term implant. So, I am told that the approval process, if things go smoothly, can be a 6-to-9-month type of process, rather than a multi-year process. I think the hurdles are not too, too significant. Now, we have extensive test on animals, but currently none of these devices have been used on humans, even in a trial type of basis. The ultimate definition for us for success is implementation in a clinical environment on humans. That’s the goal, and we’re trying to move there as fast as we can.

The kinds of devices they’re using now for monitoring neuro-activity in patients who suffer from epilepsy are crude versions, but otherwise not fundamentally dissimilar from, the devices that we’re building now. So, I think it’s not a huge leap to think that they could be tested in humans in a reasonably near-term timeframe, but I wouldn’t want to put a number on it.

How expensive would the brain implants be?

Usually these procedures are costly, and the device cost is not a significant component of the overall cost; you have surgeon time, you have hospital costs and so on. So, cost is not a main driver. I’d be surprised if that is a major consideration. I can’t give you the exact numbers, but I can tell you balloon catheters that are used in cardiac ablation procedures now are several thousand dollars, they’re one-time use devices, and it’s a small component. It’s like a 10% cost component of the overall procedure, so I don’t think there are any cost hurdles that we’re concerned with.