Characterization of micromanipulator-controlled dry spinning of micro- and sub-microscale polymer fibers

Abstract

No current microfabrication technique exists for producing room- temperature, high-precision, point-to-point polymer micro- and sub- microscale fibers in three dimensions. The purpose of this work is to characterize a novel method for fabricating interconnected three- dimensional (3-D) structures of micron and sub-micron feature size. Poly- (methyl methacrylate) (PMMA) micro- and sub-microscale fiber suspended bridges are fabricated at room temperature by drawing from pools of solvated polymer using a nano-tipped stylus that is precisely positioned by an ultra-high-precision micromilling machine. The fibers were drawn over a 1.8 mm silicon trench, and as the solvent in the solution bridge rapidly evaporates, a suspended, 3-D PMMA fiber remained between the two pools. The resulting fiber diameters were measured for solutions of PMMA in chlorobenzene with concentrations ranging from 15.5 to 23.0 wt% 495k g mol−1 PMMA and 13.0 to 21.0 wt% 950k g mol−1 PMMA. Fibers were found to increase in diameter from 450 nm to 50 µm, roughly corresponding to the increase in concentration of PMMA. To minimize fiber diameter variance, different stylus materials were investigated, with a Parylene®-coated stylus producing fibers with the lowest variance in diameter. Overall, the fiber diameter was found to increase significantly as the solution concentration and polymer molecular weight increased.