Animated and programmable LED tattoos connected to your brain? You could show off your latest Flash animations, watch TV on your arm, or have a built-in PDA screen. The possibilities are endless. Perhaps more than simply a fashion statement, you could use such LED tattoos to display medical information about your body such as blood-sugar readings. A recent article in MIT Technology Review describes a new type of super-thin silicon transistor that can be embedded on a dissolvable silk-based film and can do all of that.
Brian Litt, associate professor of neurology and bioengineering at the University of Pennsylvania, is working with researchers from Beckman Institute at the University of Illinois and Tufts University to develop medical applications for the new transistors. Their silk-silicon LEDs can act as photonic tattoos that can show blood-sugar readings, as well as arrays of conformable electrodes that might interface with the nervous system.
Professor Litt’s laboratory is a collaboration between Neurology, Neurosurgery, Neuroscience, and Engineering. While epilepsy is the lab’s core focus, other research includes implantable neurodevices, functional neurosurgery, network and computational neuroscience, movement disorders, intra-operative and ICU monitoring, major mental illness, and other brain network disorders.
Arrays of silk electrodes for… deep-brain stimulation… the electrodes can be wrapped around individual peripheral nerves to help control prostheses.
When the Rolling Stones released Tattoo You in 1981, they had little notion that in a few short years tattoos would become more than the mark of bikers, sailors, and criminals or a fashion statement for hardcore hipsters and flashy rock stars. Tattoos would soon become commonplace among middle-aged housewives and business executives. Today, companies no less prestigious than Royal Philips Electronics of the Netherlands are exploring the potential for electronic tattoos as personal body adornment and self representation. Here’s a rather sensuous video from Philips that shows the human body as a platform for electronics and interactive skin technology:
Professor Litt’s silk-based transistors promise more than just personal adornment or even medical LED tattoos. Arrays of silk electrodes for applications such as deep-brain stimulation –- used to control Parkinson’s symptoms –- can be overlaid to conform precisely to the surface of the brain’s crevice structure to reach otherwise inaccessible regions. And the electrodes can be wrapped around individual peripheral nerves to help control prostheses. So far, these flexible devices have been implanted on mice without harm (The silk degrades over time).
The researchers summarized their experiments in a recent paper, “Silicon electronics on silk as a path to bioresorbable, implantable devices,” published in Applied Physics Letters. The silicon takes the form of nanomembranes built onto water soluble and biocompatible silk substrates. And while electronics must usually be encased to protect them from the body, these electronics don’t need protection. The silk allows the electronics to match the contours of biological tissue. When wetted with saline, the devices conform to tissue surface. The silicon devices are about one millimeter long and 250 nanometers thick. They are manufactured on a stamp and then transferred to the surface of a thin film of silk. The silk holds each device in place, even after the array is implanted.
Tattooing in the Western world has its origins in Polynesia –- the first recorded encounter with the Tahitian tatau occurred during the 1769 expedition of Captain James Cook, the famed British Naval explorer. The Polynesian practice quickly became popular among European sailors, before spreading more widely. Cook’s infamous first officer William Bligh led a subsequent expedition to Tahiti in 1789 in search of breadfruit. Of the 25 mutineers aboard Bligh’s boat, HMS Bounty, court records show that twenty one had tattoos from their time in Tahiti. A century later, the royal princes, Albert and George, would visit tattooists first in Japan, then Jerusalem, while serving in the Royal Navy. The staid Cook and Bligh likely disapproved of this exotic body ornamentation at the time. Nor could they — or the royalty that later adopted the fashion — possibly envision that it might one day result in photonic LED tattoos connected to the brain.