Instead of using injections or probes, it will in future be possible to deliver drugs to premature babies via a plaster as researchers have developed a UV-activated membrane, which releases a gentle dose of medication to the skin of a patient.

The plaster, which delivers drug through the membrane, can be simply stuck to the skin of the premature baby, after which it will provide the tiny patient with a continuous dose of, say, caffeine for several hours, without stressing the child as an injection would have done.

For some years now premature babies have been given caffeine to prevent respiratory arrest.

The membrane developed at the Swiss Federal Laboratories for Materials Science and Technology changes its properties when it is irradiated with ultraviolet (UV) light.

"A similar effect is seen in photochromatic sunglasses, where silver-doped glass reacts to UV light by darkening," the researchers noted.

"In the new medicinal membranes, however, another light-sensitive chemical group, called spiropyrans, is active," they added.

When activated, these make the membrane more permeable, so that the drug is able to pass through it more rapidly, a capability which is retained for several hours.

In the absence of UV irradiation, the membrane simply prevents the active agent from permeating through it.

The study appeared in the journal Advanced Functional Materials.