banner by Helen Richard
The Sixth Sens(or)
by Helen Richard
Vivid blue, silver and black, the smiley face peers out from the jogger’s arm. It looks as though it could be a sticker, as if a child had stuck it to their parent’s arm as they were leaving for a run. Perhaps it is a tattoo. All the same, it is unassuming, barely catching the eye. Yet, it’s much more than that. Masked by the saturated colors is a network of circuits supported by flexible carbon fibers that receive data on sweat composition, weight and physicality. Biosensors may look modest, but this piece of technology has the capacity to be a new and improved Fitbit, brain monitor or even a movie ticket.
State of the art biosensors can be divided into two categories: invasive and non-invasive. Some, like the adhesive sensors developed by Joe Wang, a professor at UC San Diego’s Jacobs School of Engineering, are merely stuck to the skin like a temporary tattoo. Others are implanted under the skin, akin to traditional tattoos with ink.
“Peel and stick” biosensor tattoos interact with the body on a surface level. They can collect a variety of data like the pH of sweat and the voltage generated from electric impulses produced by the brain and muscles. These biosensors are surprisingly noncomplex in their composition, some based in silicon and others in gold leaf. Most often they look like temporary or metallic flash tattoos.
Despite their appearance of simplicity, noninvasive biosensors can still accomplish complex tasks. DuoSkin, a research project at the Massachusetts Institute of Technology (MIT) Media Lab and Microsoft Research, can act as an interface which lets a user control their phone remotely. Epidermal electronics could even be used to monitor fetus vital signs from the comfort of the mother’s living room couch. Instead of hospitals allocating money towards clunky electrocardiogram machines, they could instead purchase biosensor tattoos that would be a fraction of the price with all the same capabilities.
Implanted ink lasts longer than the non-invasive biosensors, although scientist Heather Clark at MIT hopes that sensors can be injected into shallower layers of skin so it can “slough off over time.” This brand of biosensor is created from microscopic polymer beads that contain carbon nanotubule sensor molecules, which generate fluorescence in the presence of glucose. It is currently being devised as a new method of diabetes management. Once the beads have been injected, the amount of fluorescence emitted from the nanotubule sensors can be monitored with a device worn like a watch. This watch-like device would continuously shine an infrared light on the biosensor tattoo and record the emitted florescence. This will reveal the amount of glucose in a person’s blood at essentially a constant rate. The hope is that this technology can provide diabetics with a less painful way to keep track of their glucose levels than the usual practice of finger pricks. These “invasive” biosensors are primarily still in development, although they have experienced promising results with animals.
The potential uses for biosensors are nearly endless. Just consider the following:
Picture a morning subway commute where no one is fumbling for passes. All travelers would have to do is scan their tattoo against a machine, like an E-ZPass. Or imagine a tattoo that could give the user skin care recommendations. The vice president of L’Oréal’s new technology department, Guive Balooch, has paired up with a group helmed by Dr. John Rogers, a Material Science professor at the University of Illinois, to produce biosensors with the ability to monitor skin hydration and UV exposure. A biosensor on a person’s throat can even distinguish the energy used to say basic directional commands and as a result control a cursor on a computer screen. So get ready to leave your thumb cramps in the past, because gaming marathons have just been leveled up.