Tantalum-filament pulling device for fabrication of submicrometer fused silica tips

A simple and low-cost pulling device for fused-silica capillaries was devel oped. By using a tantalum heating filament and the self-tension in a bent c apillary, tips and constricted regions with outer diameters of similar to1 mum and inner diameters of a few hundred nanometers could be reproducibly p ulled from 50-mum-i.d., 375-mum-o.d. capillaries. The tips can be used in d ifferent applications such as microinjection, micromanipulation, and single -channel patch-clamp, injection ends for CE or as electrospray tips. Constr icted capillaries with optimized dimensions to minimize cylindrical lensing effects and to match the size of a diffraction-limited laser focus can be used as optical detection windows in CE and micro-HPLC. Fused silica has: s everal advantages over other glasses such as high melting temperature and s uperior optical and mechanical properties.