Engineers develop painless needle that mimics mosquito bite

July 18th, 2008 - 12:58 pm ICT by IANS  


New York, July 18 (IANS) Indian and Japanese engineers have developed a “microneedle” that causes no pain on being inserted in the skin as it mimics the way a female mosquito sucks blood. Contrary to popular belief, a mosquito bite does not hurt. It is the anticoagulant saliva that the creature injects to stop the blood from clotting that causes inflammation and pain.

The new biocompatible microneedle has been designed by Suman Chakraborty of the Indian Institute of Technology in Kharagpur and Kazuyoshi Tsuchiya of Tokai University in Kanagawa, New Scientist reported.

A female mosquito sucks blood by flexing and relaxing certain muscles, which creates suction that draws blood into its mouth. In the needle, the sucking action is provided by a microelectromechanical pump.

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 mouth part. Its size and the fact that it works by suction makes it painless. A conventional syringe needle has an outer diameter of around 900 microns.

In contrast to previous microneedles, which were made of silicon dioxide, the new device is robust as it is made of stronger titanium alloys, which dramatically reduces the risk of it snapping during injections.

The needle is also strong enough to penetrate as far as three mm into skin and reach capillary blood vessels and can extract five microlitres of blood per second. This volume is sufficient for measuring blood-sugar levels in diabetics using a glucose sensor that can be attached to the needle in a “wristwatch” design.

The design uses a shape-memory alloy to drive the needle into skin and a micro-pump for delivering drugs. The latter could be used to inject insulin (or other drugs) into the patient when required.

Chakraborty and Tsuchiya expect to commercialise their needle, but there are still some challenges to overcome such as cost and scaling up of the fabrication method.

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