Conductive blended polymer MEMS microresonators

This paper presents an all-polymer microelectromechanical system technology in which a crosslinker is used to modify the electromechanical properties. The structural material of these microelectromechanical systems (MEMS) structures is a poly(3,4-ethylenedioxythiophene)/polystyrene sulfonate/polymethyl methacrylate (PEDOT/PSS/PMMA) blended conductive polymer. Microbridge resonators are fabricated using surface micromachining on glass substrates. The electromechanical properties of the polymer microbridges are studied using electrostatic actuation and optical and electrical detection. The resonance frequency of the polymer bridges occurs in the MHz range, with quality factors of the order of 100 when measured in vacuum. Addition of a silane-based crosslinker increases the Young's modulus of the polymer structural material which is reflected in higher resonance frequency, higher pull-in voltage, better long-term stability of the electrical conductivity, and in a decrease in the quality factor of the resonator. The mechanical properties of the polymer resonators are strongly affected by the residual stress because of the low Young's modulus, and by the measurement frequency and the measurement temperature due to the viscoelastic properties of the polymer structural material.