Microneedles are extremely small needles used to draw blood or administer drugs without penetrating the skin and underlying tissue as deeply as traditional hypodermic needles or syringes. When used for medical purposes, rows of several hundred microneedles are put onto tiny patches that are then applied to the skin. The microneedles make microscopic holes in the outermost layer of the skin, and either draw minute quantities of blood or deliver a drug, a process sometimes called transdermal drug delivery. They cause minimal pain and trauma compared to traditional needles and are used for various medical purposes like immunizations, pain management, and blood glucose monitoring. Microneedles are a relatively new medical technology and are the subject of extensive research and study.
The size of a microneedle is measured in microns. One micron is one thousandth of a millimeter, and a microneedle is usually no more than 1 micron in diameter, and 1-100 microns long. Patches coated with microneedles are described as feeling similar to sandpaper when touched. These needles are so small that they have been used to deliver drugs into individual cells. The needles can be made from a variety of materials, including metals, silicone, polymers, ceramics and glass, and are manufactured using microfabrication techniques similar to the processes used in nanotechnology and the production of microchips.
Microneedles have several advantages over syringes and hypodermic needles. They are virtually painless because they do not go deep enough to touch any nerves, penetrating only the outermost layer of the skin. The shallow penetration also means that there is less chance of infection and injury. Additionally, this technology makes it easier to deliver exactly the right amount of a drug, making it possible to use lower doses, and the development of dissolvable microneedles could help reduce the problem of discarded needles.
Microneedle patches are also cheap to make and do not have to be administered by medical professionals, making them ideal for large-scale vaccination programs in developing countries. The development of an immunization patch would also make it easier to administer childhood vaccines and seasonal flu vaccines in developed countries. Microneedles are being used for some types of blood tests, for example, blood glucose monitoring for diabetics.
The use of microneedle patches has already been studied with positive results in areas like pain management, hormone replacement therapy, and as a way to administer drugs treating congestive heart failure. Possible future uses include delivering nanoparticles into the body for various treatments, targeted gene therapy, and skin rejuvenation.
