Fabrication of a micro needle for a trace blood test

A human being has pain and fear when pricked by a needle in a blood test. On the other hand, he has almost no pain and no fear when pricked by a needle of a mosquito. Considering this fact, a new fabrication process of a micro hollow needle, which is made of SiO2 and reinforced by deposited Poly-Si, is proposed. This needle features its jagged shape like that of a mosquito, and it also features its long shape of about I mm in the direction parallel to the silicon surface. The essential points of the process are as follows: (1) wet-etching a jagged groove on Si; (2) bonding another Si substrate and sealing the grooved (3) oxidizing the wall of hollow space: (14) dry etching all parts besides the wall by ICP and RIE. Strength characteristics of the fabricated needle is investigated by experiment and finite element method simulation. It is also experimentally confirmed that this needle can actually penetrate the surface of hard silicon rubber, which is selected as an artificial skin, without breakage. (C) 2002 Elsevier Science B.V. All rights reserved.