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Flexible, Implantable Biosensor for Healthcare

In September, at KAIST (The Korean Institute of Science and Technology), a team of researchers led by Professor Keon Jae Lee of the Department of Materials Science and Engineering announced a major step forward in implanted health monitoring devices.

The challenge they were attempting to tackle was how to make a device that could be comfortably placed onto the surface of the brain, the heart or lungs, or rolled round individual arteries if necessary, detecting the spread of a disease or contagion underneath.

Their solution was the “ High Performance Flexible Single Crystal GaN” mircosensor, a flexible GaN LED biosensor.

Proof of Concept prototype

GaN LED - gallium nitride - is a highly efficient light emitting method that has been commercialized in LED TVs and in general lighting. It has always been a very hard, somewhat brittle structure with a crystalline nature. That traditionally precludes its use in anything of a flexible nature. However, as with many applications in recent years, thin strips of the material retain it's properties when banded together in array format with another, piezoelectric material, also banded into thin strips. The result is a flexible structure that has the properties of both. Add in a light detection facility with a third form of material, and cover the whole in a transparent silicone sheath, and you have a sensor that can be safely implanted inside the human body.

A sensor that illuminates diseased or damaged areas, and is able to monitor their growth or decline according to the changes in reflection from it's own illumination, across the full 3.4 eV band that GAN is capable of detecting. In other words whether the lung tumor, or stroke-damaged neurons show up better in infra-red or ultra-violet light, the same sensor can be adjusted to match both requirements without changing the hardware. This means a sensor can be implanted, then left in place, regardless of the imaging requirements.

As of yet, there are no plans for how to power such a device long-term, although other piezoelectric devices are an obvious solution there. Only a handful of prototypes exist at this stage, and research is ongoing.


Cancer detection from an implantable, flexible LED

Paper: Water-resistant flexible GaN LED on a liquid crystal polymer substrate for implantable biomedical applications, Journal of Nano Energy, September 2011

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