The idea that a small, comfortable patch could be worn on the skin and replace the need for daily injections sure is an exciting prospect. That's why we have seen numerous takes on microneedle technology, but researchers in Sweden believe they have come up with a design to top them all, with a patch that combines soft and hard materials for better performance and comfort.

Useful as they are, the hypodermic needles used for drug delivery over the past 150-plus years aren't without their flaws. They require professionals to administer them and dispose of them properly afterwards, not to mention the discomfort and pain they cause for a lot of patients.

Microneedles, on the other hand, could offer a way around these drawbacks. They are basically patches loaded up with drugs that patients can stick on themselves, with tiny needles that penetrate only the top layer of skin and leave the nerves untouched. In doing so, they drip-feed drugs over longer periods without causing any pain.

They are largely in their experimental phases, but a variety of designs have emerged over the years that promise to not just deliver drugs (including those that can keep clots from forming), but monitor their levels non-invasively as well. We have seen these made from silicon, plastics and even silk, but according to researchers at Stockholm's KTH Royal Institute of Technology, most have one thing in common in that they are made entirely from the same material.

And settling on a material to use is something of a balancing act, because when it comes to microneedle arrays you want something that is stiff enough to properly penetrate the skin, but soft enough to be comfortable to wear. But rather than trying to juggle the two, the KTH scientists looked to combine the best of both worlds.

Their solution uses a soft-polymer for the base (a molded thiol-ene-epoxy-based thermoset film, to be specific), that bears an array of 50 stainless steel needles. In testing, the team says this setup adhered well to an uneven skin surface, and that every one of the micro-needles penetrated the skin during a 30-minute application.

This proof-of-concept study is said to be the first time this combination of materials has been studied in a microneedle array, and their success demonstrates the feasibility of taking this dual-material approach. They say with further development, this kind of patch could find applications in fitness and health monitoring, diagnostics, and of course safer and more convenient drug delivery.

"The chronically ill would not have to take daily injections," says co-author Niclas Roxhed, research leader at the Department of Micro and Nano Systems at KTH. "Since the patch does not enter the bloodstream, there is less risk of spreading infections."

The research was published in the journal PLOS One.

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