Two-Photon Nanolithography Enhances the Performance of an Ionic Liquid-Polymer Composite Sensor

摘要

Continuous development of fabrication technologies, such as two-photon polymerization (2PP), allows the exact reconstruction of specific volume shapes at micro- and nanometer precision. Advancements in the engineering of new materials, such as ionic liquids (ILs), are bringing superior advantages in terms of material characteristics, facilitating a combination of optical and electrical properties, as well as lithographic capabilities. In this paper, 2PP is utilized for structuring of a novel IL-polymer composite in a single-step manufacturing process with high resolution, down to 200 nm, and high aspect ratio, up to 1:20. The composition, based on a photosensitive photoresist (e.g., IP-L 780 or SU-8) and the IL 1-butyl-3-methylimidazolium dicyana-mide, possesses a good ionic conductivity (in the range of 1-10 mS cm~(-1)) over a wide frequency bandwidth (1 kHz-1 MHz), an electrochemical window of 2.7 V, and a good optical transparency (transmission value of 90% for a 170 μm thick film). The fabricated structures are characterized and the phenomenon of enhanced conductivity (up to 4 S cm~(-1)) is explained. Two potential applications, including temperature and relative humidity sensing, are demonstrated as examples. The results suggest a new advanced approach for material structuring that can be regarded as highly most promising for a wide range of applications.