New Micro-Needle emulates Mosquito Bite

The design of a new, completely painless hypodermic micro-needle mimics the female mosquito's blood sampling techniques, and could be used for glucose monitoring, blood draws, insulin pumps, and other drug delivery devices.

The new micro-needles, developed by researchers from the Indian Institute of Technology (Kharagpur) and Tokai University (Kanagawa, Japan), are fabricated in the sputtering deposition method, and they use titanium for a more snap resistant needle. 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. In comparison, a conventional syringe needle has an outer diameter of around 900 microns. The needle is long enough to reach up to 3 millimeters deep into human skin, which is the depth needed to reach superficial capillaries; an intermittent sucking motion is generated by a micro-electro-mechanical based suction system, which works by using a piezoelectric actuator attached to the needle. The mechanism was designed by analyzing the fluidic properties of the micro-needles, and integrating them with the physiology of the blood extraction organs used to draw blood painlessly by mosquitoes. The researchers have calculated that the needle can extract 5 ìl of blood per second, a volume sufficient for measuring blood-sugar levels in diabetics using a glucose sensor. The new micro-needle was described in the June 15, 2008, issue of the Journal of Applied Physics.

"The working principle of this device follows on from our discovery that in a well-designed micro-needle, surface tension forces may overcome resistance from friction and draw up blood with unprecedented efficiency,” said codeveloper Suman Chakraborty, Ph.D., of the Indian Institute of Technology.

A female mosquito sucks blood by flexing and relaxing certain muscles in its proboscis. This creates a suction (or negative pressure) force that draws blood into its mouthparts. Contrary to popular belief, a mosquito bite does not hurt; it is the anticoagulant saliva injected to stop blood clotting that causes inflammation and pain.


Related Links:
Tokai University
Indian Institute of Technology