A characterization of micromanipulator controlled dry spinning of micro- and nanoscale polymer fibers.

Abstract

No current micro fabrication technique exists for producing roomtemperature, high-precision, point-to-point polymer nanofibers in three dimensions.Producing rounded structures in a third dimension is particularly difficult to accomplish with conventional planar micro fabrication techniques. Therefore, the purpose of this study is to characterize a novel method for fabricating such structures.In this investigation, PMMA micro-and nano-fibers have been fabricated using a technique which involves drawing a solvated polymer bridge between two liquid pools with a stylus positioned by an ultra-high-precision micromill. The solvent in the solution bridge rapidly evaporates, leaving a suspended PMMA fiber between the two pools. In order to characterize this process, fibers were drawn over a 1.8 mm silicon trench and fiber diameter was measured over a variety of different solution concentrations and polymer molecular weights. In addition, the fluid characteristics of the solutions were measured to allow for comparisons between fiber diameter and properties such as viscosity and surface tension.Fiber diameters ranging from 450 nm to 50 J.1IIl were drawn during the characterization experiments. In addition, fibers as small as 140 nm were drawn over distances less than 1.8 mm. It was observed that fiber diameter enlarged as both solution concentration and polymer molecular weight increased. In an attempt to decrease fiber diameter variance, different stylus materials were also examined, and it was found that a parylene-coated stylus resulted in a fair reduction, but not elimination, of the diameter variance. Although fiber diameter variances remain somewhat high, possibly due to unwanted solution IV buildup on the stylus tip, this fabrication technique presents a simple method for producing precisely positioned, low temperature, suspended polymer fiber structures on the micro-and nanoscale.