Researchers have developed a microneedle inspired by the the blood-sucking action of a female mosquito. Described as "painless," the microneedle has applications for blood drawing, injections, and biomonitoring. Designed by engineers at the Indian Institute of Technology and Tokai University, the device uses shape-memory alloy to push the needle into the body. Then, a microelectromechnical pump sucks out the blood or delivers the drugs. From New Scientist:
Contrary to popular belief, a mosquito bite does not hurt. It is the anticoagulant saliva that the creature injects to stop your blood clotting that causes inflammation and pain.
The new needle has an inner diameter of around 25 microns and an external diameter of 60 microns, which is about the same size as a mosquito's mouthpart. Its size and the fact that it works by suction, makes it painless. To compare, a conventional syringe needle has an outer diameter of around 900 microns.
Mosquito-inspired microneedle (New Scientist)