Focused ion beam microscope as an analytical tool for nanoscale characterization of gradient-formulated polymeric sensor

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0894-LL07-06.1

Focused ion beam microscope as an analytical tool for nanoscale characterization of gradient-formulated polymeric sensor materials Katharine Dovidenko, Radislav A. Potyrailo, James Grande Materials Analysis and Chemical Sciences GE Global Research Center Niskayuna, NY 12309 ABSTRACT In this study, we are demonstrating localized nano-scale analysis of sensor materials which are developed using combinatorial gradient approach. Our technique based on Focused Ion Beam cross-sectioning at specific locations affords establishing metal nano-particles concentrations at best-performing area(s) of gradient-formulated polymer samples. We have achieved threedimensional characterization/mapping of nano-fillers (30-100 nm metal particles) in composite thin films on variety of substrates. INTRODUCTION Development of new generation sensor materials based on engineered nanostructures is an active area of research [1]. Importantly, it requires adequate characterization tools. Among the key specific requirements for such a characterization tool are nanometer-scale spatial resolution, capability of analysis of sensor materials without altering materials composition, and, ideally, possibility of performing in-situ nanoscale analysis during exposure of sensor materials to analytes and interferences. Focused ion beam (FIB) milling is an attractive technique to address some of these along with other characterization needs of sensor materials. We take advantage of our earlier developed combinatorial and high-throughput screening expertise to accelerate the development of the sensor materials. By combining these opportunities with FIB characterization, we are able to explore gradient-formulated sensor materials on the previously unavailable level of detail. These materials were made as 30-100 nm diameter Au nanoparticles incorporated in a polymer matrix. The approach could potentially generate new knowledge on the effects of immobilized nanostructures on sensor performance. Focused ion beam preparation of sections normal to the sample surface while collecting a secondary electron image of each slice creates a powerful tool for 3-D reconstruction of materials. Application of FIB sectioning to 3-D imaging in many fields has been reported [2, 3]. In this work, we are demonstrating for the first time, to the best of our knowledge, nano-level 3D reconstruction using Focused Ion Beam serial sectioning and in-situ secondary electron imaging.

0894-LL07-06.2

EXPERIMENTAL The Au nanoparticles were incorporated in a polyvinyl alcohol (PVA) or polyvinylpyrrolidone (PVP) to produce concentration gradient in these polymer matrixes as described earlier [4]. We have studied an addition of different size particles ranging from 30 to 100 nm, but with narrow size distribution in each case. The polymer-Au composite matrix was typically fabricated on glass slides to facilitate optical testing of the materials. Chemical response of Au-nanoparticle/polymer composite films has been evaluated using an optical setup described elsewhere [5]. In this