AVS 52nd International Symposium
    Nanometer-Scale Science and Technology Thursday Sessions
       Session NS-ThA

Paper NS-ThA9
Engineering of Porous, Tin Oxide Nanoparticle Microshells for Chemical Sensor Applications

Thursday, November 3, 2005, 4:40 pm, Room 210

Session: Nano Processing
Presenter: C.J. Martinez, National Institute of Standards and Technology
Authors: C.J. Martinez, National Institute of Standards and Technology
C.B. Montgomery, National Institute of Standards and Technology
B. Hockey, National Institute of Standards and Technology
S. Semancik, National Institute of Standards and Technology
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Advanced sensors for applications ranging from homeland security to space exploration will require performance characteristics that include high sensitivity and rapid response. We have sought to enhance the sensitivity and speed of conductometric gas microsensors through the design and fabrication of porous, three-dimensional tin oxide nanoparticle (@td 10@ nm) films. These films were fabricated via the self-assembly from solution of nanoparticle-decorated latex microspheres, which serve as sacrificial templates. Through heating (10@super 4@ @super o@C/sec), the latex microspheres were removed to reveal a multiscale porous 3-dimensional structure composed of interconnected hollow nanoparticle microshells with ultra-thin walls (@td 50@ nm). The multiscale porous architecture promotes analyte diffusion and maximizes available active surface area. Sensor measurements were performed by depositing these films onto MEMS microsensor platforms with inter-digitated electrodes and embedded heaters. We report on film conductance changes measured at different temperatures (300@super o@C to 450@super o@C), caused by exposure to test gases at concentrations @td 100@ ppb in a dry air background. An enhancement in sensitivity to CO, H@sub 2@O and MeOH was observed for these nanoparticle microshell films when direct comparisons were made to other nanostructured sensing films. Special attention has been given to understanding the influence that structural factors (film thickness, packing density, microshell diameter and microshell thickness) have on the sensitivity, selectivity, stability and response time of these materials.