No one likes frequent injections, and taking multiple oral medications throughout the day can be annoying. A new wearable patch could help, painlessly delivering medication through the skin when triggered by a smartphone. This experimental device, called Spatiotemporal On-Demand Patch (SOP), was developed at the University of North Carolina by a team led by Professors Bai Wubin and Song Juan. It's a variation of an existing gadget called a microneedle patch.

The Spatiotemporal On-Demand Patch (SOP), in actual use, will be covered by a protective material similar to a Band-Aid University of North Carolina

Typically, the patch takes the form of a small polymer sheet with an array of tiny, sharp, drug-laden studs (also known as microneedles) at its base. When the patch is applied to the body, the needles painlessly penetrate the top layer of skin. They then dissolve harmlessly and release the drug into the body.

SOC is somewhat different. It has a circuit on its upper surface, the needles can be loaded with different drugs individually, and all needles are covered with a thin gold film. This coating prevents the needles from dissolving when the patch is initially applied to the skin.

However, when a nearby smartphone (or computer) emits a wireless signal to activate the patch, the SOC heats one or more microneedles, causing the gold coating on the needles to dissolve. The microneedles themselves are then exposed directly to the skin, dissolving and releasing their payload within 30 seconds. Like other microneedle patches, the drug first enters the stroma between skin cells and is then carried into the bloodstream.

In current laboratory tests, SOP has been successfully used to inject multiple doses of melatonin into mice. It is hoped that the technology could eventually be used to treat chronic conditions such as Alzheimer's disease, by injecting different drugs throughout the day on a predetermined schedule.

Song Juan said: "The advantage of this kind of equipment is that it can hold dozens or even hundreds of concentrated drugs and can automatically release them in sequence according to the program."

A paper on the research was recently published in the journal Nature Communications.