A polymethylmethacrylate (PMMA) nanowire was prepared by electrospinning and attached to the two prongs of a quartz tuning fork (QTF) to form a polymer bridge. The attachment of the wire increased the resonance frequency due to an increase in the stiffness of the QTF. The resonance frequency of the PMMA wire-coated QTF decreased upon exposure to water vapor, which was attributed to a decrease in the modulus of the wire induced by the adsorption of moisture. The sensitivity of the PMMA wire-coated QTF was enhanced by increasing the number of PMMA wires on the QTF without affecting the response time of the sensor.