Friday, August 26, 2011

#SENSORS: "Tattoo-Like Sensors Monitor Brain and Muscles"

Wearable electronic devices can be deposited on the skin like a temporary tattoo.

Electronics have been successfully transferred from a dissolvable carrier to the skin, enabling tattoo-like sensors to monitor brain waves and muscle actions for everything from remote medical diagnosis to immersive gaming to spy-inspired covert surveillance.

The next time you see an indecipherable tattoo in San Diego it could be an experimental new electronic sensor being tested by bioengineering professor Todd Coleman. While the device was invented by engineering professor John Rogers who worked with Coleman at the University of Illinois along with Northwestern University engineering professor Yonggang Huang, Coleman is now perfecting applications for the device at UCSD.

An example of tattoo-like wearable electronic devices. (Source: University of Illinois)

The smarter part of the device is its use of a flexible water-soluble substrate on which sensors and eventually wireless transmitters can be integrated. The substrate can deposit the electronics on the surface of the skin, then be dissolved leaving only the electronics behind on the skin. This is a process that is similar to that used with a temporary tattoo (minus its paper carrier).

In the lab, the researchers have installed sensors on a subject's skin to monitor muscular movements that controlled a computer game with sub-vocalization, which the team envisions as a prelude to covert sensors that military surveillance operatives could use to communicate sighting details in complete silence.

Today the kind of electrodes that can monitor such muscle motions are bulky and require a firm attachment to the skin, often requiring messy conductive pastes for optimal performance. However, the wearable tattoo sensors being perfected by Coleman's team are claimed to have all the desirable attributes of standard electrodes minus the bulk and messy paste.

Many patients have debilitating conditions that could benefit from 24/7 monitoring, such as epileptics whose seizures could be predicted if they constantly wore electrodes, but the rarity of attacks is too infrequent to warrant the inconvenience of wearing electrodes. Many other medical conditions could also benefit from 24/7 monitoring, which could be made more convenient with Coleman's tattoo-like sensor arrays.

Next, Coleman's team is working toward integration of the tattoo-like sensors with the rest of the circuitry required to create a wireless sensor node. For instance, by adding an active transmitter to the passive sensors, the device could monitor muscles or even brain waves and use the results for diagnosis or to control communications or even games.

Meanwhile, Roger's team back at the University of Illinois is developing electronics that can be integrated onto human organs. For instance, Roger's team is working on an electronic eyeball camera that adapts to the curvature of the eye for improved imaging. And another sensor model can be deposited directly on the heart to monitor its beating. Eventually, Rogers hopes to perfect implantable sensors that could provide high-resolution mapping of the electrophysiology of the brain, heart, and other organs, as well as be integrated with other electronics to correct maladies that require periodic electronic stimulation.

Funding was provided by the National Science Foundation and the Air Force Research Laboratory.

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