Elizabeth Crew - Flexible Chemiresistor Sensors: Thin Film Assemblies of Nanoparticles on Polyethylene Terephthalate Substrate

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      Publication Details (including relevant citation   information):

      L. Wang, J.Luo, J. Yin, H. Zhang, J. Wu, X. Shi, E. Crew, Z. Xu, Q. Rendeng,   S. Lu, M. Poliks, B. Sammakia , C. J. Zhong, J.   Mater. Chem., 2010, 20, 907–915.

      DOI: 10.1039/b920957c

      Abstract:

      The thin film assembly of metal nanoparticles on flexible   chemiresistor (CR) arrays represents an

      intriguing way to address the versatility of chemical sensor   design. In this work, thin film assemblies

      of gold nanoparticles in size range of 2–8 nm diameters with high   monodispersity (unlinked or linked

      by molecular mediators) were assembled on aCRarray with a   polyethylene terephthalate (PET) substrate

      to demonstrate the flexible chemiresistor characteristics of the   nanostructured materials. The correlation

      between the relative change in electrical conductivity and the   change in dielectric medium constant in

      response to flexible wrapping of the device demonstrated the   viability of manipulating the electrical

      responses in terms of wrapping direction. The responses of the   devices in response to volatile organic

      compounds (VOCs) were analyzed in terms of particle size,   interparticle properties, and substrate–film

      interactions. For molecularly linked films with small particle   size and large interparticle spacing, which is

      characterized by a high percentage of organics and linker   molecules, the relatively low electrical

      conductivity renders the change in interparticle spacing able to   play a dominant role in the sensor response

      to VOCs with small dielectric constants. The combination of a   high percentage of linker molecules in

      the thin film assembly and a high dielectric constant for the   VOCs was found to produce a negative

      response characteristic. In contrast, the response characteristic   for the unlinked filmvia weak interparticle

      interactions was dominated by the change in interparticle spacing   regardless of the percentage of organics

      in the nanostructure. The delineation between these factors and   the sensing characteristics is useful in

      enabling a rationale design of the nanostructures on flexible   chemiresistors.

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