A new graphene biosensor design, just four atoms thick, could overcome the limitations of its comparatively clunky predecessors and one day find itself in peoples' brains, on their eyes, and anywhere else on the body where the body's electrical signals could usefully be, well, sensed.Conductive biosensors that measure electrical activity in the brain allow neuroscientists to track what, exactly, is happening in that mysterious organ when we—okay, I—do things like decide to eat an entire pizza instead of hit the gym. But traditional sensors have a problem: they're often metallic, rigid, and interrupt other methods of brain scanning like MRI, infrared, and ultraviolet scanning.
Advertisement
According to a new Nature Communications paper by University of Wisconsin-Madison engineers, brain research techniques like optogenetics—genetically modifying neurons to be stimulated by light—require new kinds of transparent sensors that won't block portions of the brain from being investigated. Next gen brain sensors also need to allow for other, more traditional imaging techniques. Because a sensor with these specific attributes doesn't exist yet, they made one.
"Historically, we've kind of looked at one or the other: we either take high-resolution imaging to look at how the brain is structured, or we poke and prod it with electrodes to try and measure its activity," Justin Williams, a professor of biomedical engineering and one of the paper's authors, told me. "The function can be hard to get at because it's very fleeting. It's very fast, and the signals come and go. What we're trying to do here is let you do both."Metal electrodes show up as unhelpful black squares during MRI or ultraviolet scans, and current flexible designs block certain frequencies. Graphene, a superconductive material with all kinds of insanely futuristic applications, provided the perfect base for the new sensor design, Williams said.Graphene can be manufactured in atom-thick layers, and can be transparent to the vast majority of the light frequency band—letting in more than 90 percent of frequencies from the ultraviolet to the infrared spectrum. It can also be made extremely small and flexible; when fitted onto small latex strips, it's a slightly less invasive alternative to the rigid electronic electrodes currently in use.
Advertisement
Blood flowing past the team's sensors, shown as the translucent circles.The first application of the new sensors will certainly be in neuroscience research, since they allow for unprecedented levels of brain activity monitoring. Still, a conductive sensor is an extremely versatile device, and one as small and transparent as the new graphene design is doubly so. From prosthetics that link up to the brain to monitoring for electrical activity in any part of the body you want, the new sensor could have numerous clinical applications, such as smart contact lenses."We've been working with Professor John Hetling at the University of Illinois, Chicago, to put them in contact lenses so we can record activity in the retina from the surface of the eye, and be able to diagnose diseases that way," Williams told me. "Now we can make contact lenses that are perfectly clear, but are blanketed with sensors that are usable from a clinical perspective."The sensor design can be easily modified to detect more than just electricity, WIlliams added. Most biosensors have an electrical conductor at their core anyway, like this e-tattoo that can tell how hard you're working out. Modifying a graphene sensor would just be a matter of adding whatever additional sensors you'd need, although they would presumably have to be just as small and flexible as the graphene lest they defeat the entire purpose.
The thought of transparent, sensor-laden contacts that actively monitor the electricity in my eyes definitely lights up the "holy shit" region of my science fiction-addled brain (note: this region may not actually exist), but the new sensor design will require a ton of research and testing before it makes its way into clinics and research labs beyond Williams's.The longevity of the sensors needs to be assessed in long-term trials, which are currently underway. If they break down in the brain or the body rejects them they'll be useless, but after a few months of testing in rat brains, Williams tells me, they seem to be doing fine.Manufacturing costs need to be brought down as well, if the sensors are ever going to be made in greater numbers. With DARPA funding and membership in the US government's BRAIN initiative, research and development costs for the project shouldn't be an issue.Graphene biosensors are pretty cutting edge stuff, and previous generation technology is still struggling for acceptance among clinicians, Williams noted. The technology's adoption may depend, in part, on the willingness of practicing doctors to try it out. Most of the time, clinicians desire proven methods and incremental changes over complete overhauls of practice. And so, like with nearly any new technology, Williams said, "Baby steps building towards this is the right avenue."
ONE EMAIL. ONE STORY. EVERY WEEK. SIGN UP FOR THE VICE NEWSLETTER.
By signing up, you agree to the Terms of Use and Privacy Policy & to receive electronic communications from Vice Media Group, which may include marketing promotions, advertisements and sponsored content.
"Historically, we've kind of looked at one or the other: we either take high-resolution imaging to look at how the brain is structured, or we poke and prod it with electrodes to try and measure its activity," Justin Williams, a professor of biomedical engineering and one of the paper's authors, told me. "The function can be hard to get at because it's very fleeting. It's very fast, and the signals come and go. What we're trying to do here is let you do both."Metal electrodes show up as unhelpful black squares during MRI or ultraviolet scans, and current flexible designs block certain frequencies. Graphene, a superconductive material with all kinds of insanely futuristic applications, provided the perfect base for the new sensor design, Williams said.Graphene can be manufactured in atom-thick layers, and can be transparent to the vast majority of the light frequency band—letting in more than 90 percent of frequencies from the ultraviolet to the infrared spectrum. It can also be made extremely small and flexible; when fitted onto small latex strips, it's a slightly less invasive alternative to the rigid electronic electrodes currently in use.Blood flowing past the team's sensors, shown as the translucent circles.The first application of the new sensors will certainly be in neuroscience research, since they allow for unprecedented levels of brain activity monitoring. Still, a conductive sensor is an extremely versatile device, and one as small and transparent as the new graphene design is doubly so. From prosthetics that link up to the brain to monitoring for electrical activity in any part of the body you want, the new sensor could have numerous clinical applications, such as smart contact lenses."We've been working with Professor John Hetling at the University of Illinois, Chicago, to put them in contact lenses so we can record activity in the retina from the surface of the eye, and be able to diagnose diseases that way," Williams told me. "Now we can make contact lenses that are perfectly clear, but are blanketed with sensors that are usable from a clinical perspective."The sensor design can be easily modified to detect more than just electricity, WIlliams added. Most biosensors have an electrical conductor at their core anyway, like this e-tattoo that can tell how hard you're working out. Modifying a graphene sensor would just be a matter of adding whatever additional sensors you'd need, although they would presumably have to be just as small and flexible as the graphene lest they defeat the entire purpose.