AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Gas Detection by Engineered Multi-scale Structures Composed of Nanoparticles
YONGJUN BAE, Woongsik Nam, Hyesung Cho, Mansoo Choi, Seoul National University
Abstract Number: 237 Working Group: Nanoparticles and Materials Synthesis
Abstract The three-dimensional (3D) structures in a nanoscale dimension have been demonstrated for various sensor devices such as molecular or gas sensing platforms via conventional or non-conventional patterning approaches. Here, we present multiscale 3D gas sensors by utilizing an ion assisted aerosol lithography method, which induces a spontaneous self-assembly of charged ions to generate complex structures from thin films to flower-like architectures. In this method, we collected and focused an amount of nanoparticles to form an array of the porous bridges by simply generating charged nanoparticles (~ 5 nm in diameter) in a spark discharge chamber. A variety of metals can be employed to make the aforementioned nanoparticles such as copper, tin, carbon in a reproducible and controllable manner. The obtained structures are sufficiently robust to measure the changing of the gas concentration in a sensing chamber, resulting in a significant sensing ability for the introduced gases. By performing various sensing experiments with 3D lines and bridges, the presented sensor shows a relatively high sensitivity, based on a change of the resistance [S=(R_gas - R_air)/R_air] against to the external CO gas by comparison to a film-like 2D sensor. This is mainly due to the fact that our 3D metallic structures from self-assembly have nanoscale pores in its surface to make an easy diffusion of the target gases so that a rapid and reliable absorption of the gas molecules was occurred around the surface of the structure. In the experiment, 3D sensor from the self-assembly of copper oxide shows much enhanced sensing result (S=1.65) at 100 ppm of the CO, which is more sensitive than other type of 2D structures (film, lines). Also we can modulate the porosity of the structured sensors by utilizing an IAAL technique with much larger nanoparticles, finally resulting in a successful 3D gas sensor application.