Why wait for the doctor to see you? A smart patch attached to your skin could diagnose health problems automatically – and even administer drugs.

Monitoring movement disorders such as Parkinson's disease or epilepsy relies on video recordings of symptoms and personal surveys, says Dae-Hyeong Kim at the Seoul National University in South Korea. And although using wearable devices to monitor the vital signs of patients is theoretically possible, the wearable pads, straps and wrist bands that can do this are often cumbersome and inflexible.

To track the progression of symptoms and the response to medication more accurately would require devices that monitor cues from the body, store recorded data for pattern analysis and deliver therapeutic agents through the human skin in a controlled way, Kim says.

So Kim and his team have developed an adhesive patch that is flexible and can be worn on the wrist like a second skin.

Hot stuff

The patch is 1 millimetre thick and made of a hydrocolloid dressing – a type of thin flexible bandage. Into it they embedded a layer of silicon nanoparticles. These silicon nanomembranes are often used for flexible electronics, and can pick up the bend and stretch of human skin and convert these into small electronic signals. The signals are stored as data in separate memory cells made from layers of gold nanoparticles.

The device could be used to detect and treat tremors in people who have Parkinson's disease, or epileptic seizures, says Kim. If these movements are detected, small heaters in the patch trigger the release of drugs from silicon nanoparticles. The patch also contains temperature sensors to make sure the skin doesn't burn during the process.

For now it relies on an external power source, but it could be powered by other devices worn on the wrist, such as a watch, says Kim. Similar devices in future might be powered by the wearer's movements.

Wearable skin

Kim thinks the device is about five years away from being used in healthcare. But Alexandra Porter at the London Centre for Nanotechnology at Imperial College London is not convinced. "This is a nice device as it combines a sensor with a therapeutic as a 'wearable skin'," she says, but it still has a long way to go – especially with regards to the drug administration.

Kim says that there are ointment-like drugs available that have been approved by the US Food and Drug Administration that would work with the device. But according to Porter, even if the drugs do cross the skin and get into the bloodstream, for Parkinson's disease they would need to reach the brain, and cross the blood-brain barrier, which most drugs cannot do.

Ijeoma Uchegbu a pharmaceutical neuroscientist at University College London says the device is a "remarkable feat of engineering", but agrees that finding the right drugs to cross the skin might be a limitation. Instead, she says, it could be developed as an implantable device for cardiac patients. "All in all it's a formidable effort," she says.

Journal reference: Nature Nanotechnology, DOI: 10.1038/NNANO.2014.38