Transdermal patches are already in use as an alternative form of dispensing medication. Of particular use when medication is very powerful, or needs to be dispensed slowly over time, these patches allow drugs to be absorbed through the skin. The only problem is, these transdermal patches can only be used when the medication is made up of molecules that are small enough to be absorbed through the wearer’s skin.
In an effort to expand use of the transdermal patch to medications with larger molecules, researchers at Purdue University have developed a tiny micropump that could be used to drive drugs under the skin automatically. Rather than devise a bulky gadget that would need batteries, the scientists have built a pump that is activated by body heat and relies on the natural process of fermentation to trigger the medication flow.
In a typical transdermal patch, drugs are placed behind a porous membrane covering a reservoir of medication. In some cases, body heat is used to melt thin layers of medication embedded in the adhesive. This medication then enters the body through skin pores, and eventually the blood stream.
The micropump system developed at Purdue would work slightly differently. The micropump would contain Baker's yeast and sugar in a small chamber. When water is added and the patch is placed on the skin, the body heat and the added water cause the yeast and sugar to ferment, generating a small amount of carbon dioxide gas. Scientists anticipate that this energy could be used to power an array of microneedles that could supply a flow of medication into the body. "The gas pushes against a membrane and has been shown to continually pump for several hours," said Babak Ziaie, a professor of electrical and computer engineering and biomedical engineering.
These new body heat-activated patches would be useful in a number of ways: First, a wider variety of medications could be delivered transdermally eliminating the possibility to forget a dose or abuse a substance. Second, they can be mass produced at a relatively low cost and then disposed of. Third, they wouldn't need expensive batteries that would have to be replaced.