Techniques for microscale patterning of zeolite-based thin films

Micro- and nano-scale devices have made a significant impact on electrical, optical, mechanical, and medicinal platforms, such as microchips, environmental sensors, and smart implants. Of particular interest for these devices is the use of nanoporous materials, such as aerogels, zeolites, and mesoporous materials, whose inherent nano- to micro-scale porosity provides potentially beneficial properties that could be harnessed for these devices, particularly when the materials are synthesized in thin film form. However, the primary challenge to utilizing these materials remains the ability to fabricate or pattern the thin film materials into appropriate micro- and nano-scale features. A number of techniques have been developed to address the issue of patterning thin films of nonporous materials, from bottom-up approaches, like chemical or mechanical assembly, to top-down approaches, such as sputtering, ablation, and lithography. However, most of the patterning techniques represented in the literature for thin film materials are typically less compatible with porous thin films, particularly microporous and mesoporous thin films. Here, we present a review of the various patterning techniques that have been either heavily investigated or proposed for microporous thin film materials, along with their advantages and potential limitations. Specifically, we focus on top-down, bottom-up, and deposition-based approaches that have yielded micro- to nano-scale patterning abilities for zeolite-based materials. Given the unique physical, chemical, mechanical, and structural properties of zeolites and other inherently-nanostructured materials, the ability to choose and adapt an appropriate patterning technique will greatly enhance the success of their utilization in micro-scale and potentially nanoscale device fabrication. (C) 2014 Elsevier Inc. All rights reserved.