Microwriting Using Surface Tension

摘要

The design, construction, and evaluation of a non-contact microwriting system is presented. The device is based on standard technical pen nibs, which have a wire whisker inside a hollow tube. Writing with these pens normally requires contact with the writing surface (substrate). By taking advantage of surface tension and capillary forces, once a meniscus is formed on the writing surface, if the pen is lifted above the surface, fluid will continue to wick from pen to substrate—even if the pen no longer touches the surface. A vacuum preloaded air bearing is used to control the pen height above the surface and also to control the pressure differential across the pen. This can control both line width and line thickness of the fluid deposited, to widths smaller than pen widths. Lines approximately 25 microns wide have been deposited with 0.10 mm diameter pens, with suitable pressure and height regulation. The advantages with this deposition method are reduced use of fluids, and no damage to the substrate. This apparatus is used in research of surface properties and for use in biochemical sensors and assays.