Chemical sensing with micromolded plastic microcantilevers

This paper describes microcantilever sensors produced via injection molding. The injection mold design is novel in that it employs one floating and one fixed mold half, hence only necessitating high flatness on two surfaces (e.g., the mating surfaces of the mold), whereas the remainder of the mold can be machined to only moderate tolerances. The mold holds a sub-100 nanometer flatness error over the entire mold mating surfaces, needed to produce micro- and nanoscale parts. Micrometer-scale cantilevers are produced and characterized as a test case. Microcantilevers are fabricated from three different polymeric materials and have exceptional repeatability as evidenced by their measured first-mode bending resonant frequencies. As a precursor to biological sensing, gold-thiol chemical sensing results obtained with the injection-molded cantilevers are also presented and show values that agree with the literature. As a whole, this work shows that the polymeric microcantilever parts fabricated via injection molding are mechanical and functional equivalents to their silicon-type counterparts, and are cheaper and easier to manufacture. [1483].