Gold nanoparticle superlattices: correlating chemiresistive responses with analyte sorption and swelling

Abstract

In this study the chemiresistive responses of gold nanoparticle superlattices are investigated by GISAXS and microgravimetry.

Decoration of Nanofibrous Paper Chemiresistors with Dendronized Nanoparticles toward Structurally Tunable Negative‐Going Response Characteristics to Human Breathing and Sweating

“…Note that the responses to other alcohol vapors such as methanol and propanol also display negative‐going response profiles. These response profiles exhibit a remarkable contrast to most of the traditional chemiresistors assembled by polymers or nanoparticles with molecular linkers (alkyl dithiols and alkyl dicarboxylic acid) on flexible or rigid substrates (PET and glass), which exhibited often positively going response characteristics in terms of Δ R / R i , but less often negative‐going responses depending on the interparticle dielectric medium properties . In the assembly of the dendronized Au NPs, the persistence of the negative‐going response profiles observed in this work is indicative of a significant impact of an increase of the interparticle dielectric medium constant as a result of the highly branched dendrons with both hydrophilic and hydrophobic structures in the 3D matrix on the electrical conductivity.…”

“…For breath or sweat sensors for human performance monitoring, the ability to monitor the moisture‐dominated breathing and sweating processes is critical for the sensor differentiation of other chemical or biological species from the moisture‐dominated environment. Technically, chemiresistors present the easily adapted format for wearable sensor devices, which are characterized most often by positive‐going responses (increases in resistance upon molecular adsorption into the sensing film), and less often by negative‐going responses, to the targeted chemical species, as demonstrated in our previous works and others . In order to differentiate different volatile organic compounds (VOCs) in moisture‐dominant environments such as breath and sweat, highly tunable response profiles are desired for the sensor elements in a sensor array.…”

Gold nanoparticle superlattices: structure and cavities studied by GISAXS and PALS

“…In order to validate the above described model based on GISAXS and TEM data, the mass fractions of gold n Au respectively organic material were calculated based on this model (similarly as has been shown in our previous work 36 ) and compared to the mass fractions n Au,TGA determined by thermogravimetric analysis (TGA). For calculating the mass fractions it was assumed that apart from the space lled by the spherical gold cores all space within the superlattice lms was lled with liquid 1-dodecanethiol (see the ESI for details †).…”

“…However, while GISAXS is a precise method to determine lateral distances, it was not used to extract the particle sizes because the intensity ratio of the (111)-and (200)-reection, from which in principle the particle diameters can be derived, is affected by texture effects, as outlined earlier. 36 Hence, for determining the edge-toedge distance d between adjacent gold cores (see Table 1) the TEM-measured GNP core diameters were subtracted from the center-to-center nearest neighbor distances obtained by GISAXS measurements.…”

“…Regarding chemiresistive sensing cavities are generally presumed to play a major role in the sensing mechanism. 7,36 Indeed, several studies indicated their inuence on the sensing properties. [37][38][39][40] For example, assemblies of thiol-stabilized cubic platinum nanoparticles, revealing a more compact structure than their spherical counterparts, showed considerably higher response amplitudes.…”