Production and Analysis of Polymeric Microcantilever Parts

Abstract

This dissertation presents work involving the manufacture and analytic modeling of microcantilever parts (length-width-thickness of roughly 500-100-10 microns). The manufacturing goals were to devise a means for and demonstrate repeatable production of microcantilevers from techniques not used in the integrated-circuit field, which are the exclusive means of current microcantilever production. The production of microcantilevers was achieved via a solvent casting approach and with injection molding, which produced parts from various thermoplastic polymeric materials (amorphous, semi-crystalline, fiber- and nanoclay-filled) in a repeatable fashion. Limits of the injection molding process in terms of the thinnest cantilevers possible were examined with 2 microns being the lower bound. Subsets of the injection-molded parts were used in a variety of sensing applications, some results were successful (e.g., vapor-phase, resonance- and deflection-based sensing), while others showed poor results, likely due to experimental shortcomings (e.g., fluid-phase, deflection-based sensing). Additionally, microcantilever parts with integrated tips were injection-molded and showed to function at the same level as commercial, tipped, silicon-nitride parts when imaging an optical grating; this experimental work was the first demonstration of injection-molded parts for chemical sensing and force spectroscopy. The scientific results were (i) the derivation of a length scale dependent bending stiffness and experimental evidence showing that such an effect was observed, (ii) the development of a new microcantilever experimental mode (surface stress monitoring via microcantilever bending resonant frequencies) and experimental validation of the technique, and (iii) a new method for determining microcantilever geometry based upon measurement of a bending, lateral, and torsional mode and experimental validation of the procedure.