Mosquito Needles

One of the problems for many people, with having an injection, is the fear created by the pain of the needle piercing the skin. If you have been in tropical climes then you most certainly have had the pleasure or otherwise of being bitten by a mosquito. The mosquito can stab you, without you feeling a thing, with its proboscis and then inject anticoagulant saliva to stop your blood clotting, while it feeds. It is this that carries the bacteria that cause irritation and pain and you become aware of the bite.

Dr Seiji Aoyagi of Kansai University in Osaka, Japan has, with his colleagues developed a needle that is serrated and barely touches the skin, just like a mosquito, so you don’t feel a thing. It is delicate and is driven by tiny motors based on lead zirconium titanate, a piezoelectric crystal that vibrates at about 15hertz to control how the needle enters the skin.

Dr Aoyagi and his engineering team created a needle just one millimetre long and 0.1 millimetres in diameter. They bonded together slices of silicon dioxide into a jagged shape made by etching. The needle’s walls are only 1.6 micrometres thick. This is unlike a normal syringe that has a larger area of metal in touch with the patient’s skin, causing interaction with person’s pain sensors and their subsequent reaction.

Professor Suman Chakraborty of the Institute of Technology in Kharagpur, an expert in micro fluidics engineering, has worked on several designs of a similar nature in the past and believes that the new design by Dr Aoyagi is a substantial improvement in technology.

Dr Aoyagi believes that this could be the beginning of production of small wireless devices with the micro needle permanently attached to the patient’s body.  With a five-millimetre-wide tank attached it could collect blood and fluids to be monitored for blood sugar levels or other chemical items for lab analysis.

Further work is being undertaken on the design to mimic additional mouth parts of the mosquito in order to reduce stimulation of the nerve fibres causing the little pain experienced in tests.


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