Fabrication of array of hollow microcapillaries used for injection of genetic materials into animal/plant cells

We have proposed a micromachined system with the aim of controlling injecti on of DNA into cells. The injection system is composed of two components: h ollow microcapillaries for injection and microchambers for trapping cells. The hollow microcapillary array, the most important part of the system has been fabricated. In this paper, we present a micromachined DNA injection sy stem and the fabrication of hollow microcapillary array. Bosch deep reactiv e ion etching (RIE) etching was used to etch small, deep holes, approximate ly 5 mu m in diameter and 100 mu m in depth, on a silicon substrate, and en abled the fabrication of microcapillaries with microchannels inside. The fa bricated hollow microcapillaries are 1 mu m in thickness, 30 mu m in length and 5 mu m in diameter and are made of SiO2. The height of the microcapill aries can be easily controlled. Silicon substrate with microcapillaries is bonded anodically with a processed glass substrate, and enables the silicon membrane to endure pressure from outside during DNA injection. By back-sid e silicon etching in TMAH solution and making holes on tips of microcapilla ries, the fabrication of hollow microcapillaries is completed. Hollow micro capillary arrays can also be used in some applications other than DNA injec tion, such as microchannels in fluid delivery systems.