Authors: T.J. Kang, E.Y. Jang, J.H. Lee and Y.H. Kim
Affilation: Seoul National University, Korea
Pages: 210 - 213
Keywords: nanocomposite, membrane, carbon nanotube, polyelectrolyte
Highly sensitive sensor arrays are critical for prospective devices and demanded for various applications. Measuring microscopic deflections with sensitive membranes is one of the most versatile approaches for pressure, acoustic, chemical and biomolecular sensing. Here we present an innovative fabrication of compliant and ultra-thin nanocomposite membranes with nanoscale thickness showing extraordinary sensitivity and dynamic range, which makes them candidates for a new generation of membrane-based sensor arrays. The nanomembranes have the thickness of 23 nm and can be freely suspended over large (hundred micrometres) openings. They are fabricated with molecular precision by spin-assisted layer-by-layer assembly. All the processing steps can be performed with conventional microfabrication facilities, and the MEMS-compatible fabrication process can be immediately applied. Nanocomposite membranes are designed as multilayered molecular composites made of the combination of polymeric monolayers and single-wall carbon nanotubes (SWNTs) interlayer. Spin assisted layer-by-layer approach enhances load sharing capacity of homogenously distributed SWNT networks in the in-plane direction as well as a bridging effect of SWNTs along the out-of-plane direction between the upper and the lower polymeric matrices by covalent bonding. Moreover, these nanocomposite membranes are electrically conductive, and the SWNT networks formed by spin-coating show very low electrical percolation threshold with the critical exponent value of 1.4. The present free-standing and ultra-thin nanomembranes can serve as components for a variety of long-lifetime and highly sensitive sensors.