Development of Minimally Invasive Microneedle Made of Tungsten – Sharpening Through Electrochemical Etching and Hole Processing for Drawing up Liquid Using Excimer Laser –

A tungsten needle was fabricated by electrochemically etching a thin wire with a diameter of 100 µm, with the goal of using it in minimally invasive medical treatments. The sharpness and smoothness of the tip were effective for easy insertion because they provided a large stress concentration and small amount of friction, respectively. An experiment involving the insertion of the fabricated needle into artificial skinmade of silicone rubber was carried out. The resistance force during the insertion was greatly reduced because of the small size of the needle, which was comparable to a mosquito’s proboscis. Despite the ultra-thin shape, the microneedle neither buckled nor broke because of the high hardness of the tungsten material. A hole was fabricated in the tungsten needle using excimer laser processing and electrochemical etching. Water and blood sampling were successfully achieved using this needle.