Molecularly Mediated Thin Film Assembly of Nanoparticles on Flexible Devices: Electrical Conductivity versus Device Strains in Different Gas/Vapor Environment

Abstract

The ability to precisely control nanoparticle-enabled electrical devices for applications involving conformal wrapping/bending adaptability in various complex sensing environments requires an understanding of the electrical correlation with the device strain and exposure to the molecular environment. This report describes novel findings of an investigation of molecularly mediated thin film assembly of gold nanoparticles on flexible chemiresistor devices under different device strains and exposure molecules. Both theoretical and experimental data have revealed that the electrical conductivity of the nanoparticle assembly depends on a combination of the device strain and the exposure molecules. Under no device strain, the electrical conductivity is sensitive to the molecular nature in the exposure environment, revealing a clear increase in electrical conductivity with the dielectric constant of vapor molecules. Under small device strains, the electrical conductivity is shown to respond sensitively to the strain directions (tensile vs compressive strain) and also to the dielectric constant of the vapor molecules in a way resembling the characteristic under no device strain. Under large device strains, the electrical conductivity is shown to respond to the difference in dielectric constant of the vapor molecules but, more significantly, to the device tensile and compressive strains than those under small device strains. This combination of device strain and dielectric characteristic is also dependent on the orientation of the microelectrode patterns with respect to the device strain direction, a finding that has important implications to the design of flexible arrays for a complex sensing environment.

A molecular-gap device for specific determination of mercury ions

“…The most intriguing feature of the devices is that they can directly transduce events of the molecules' specific binding into useful electrical signals, such as resistance/impedance, capacitance/dielectric, or field effect12. Of particular interest is the nanogapped gold particle film based on interdigital gold electrodes34567891011. Some impressive works can be tracked back to studies conducted by Nagaoka, Murray and their colleagues.…”

Nanoparticle-Structured Highly Sensitive and Anisotropic Gauge Sensors

“…Among different nanoparticle‐based electronic pressure sensors, gauge factors are reported to range from 10 to 200 for 2–18 nm sizes . For a device to function as both chemical and gauge sensors, the device is desired to be deformation‐tolerant so that the chemical sensing is not affected, and to response to both chemical and strain so the sensor exhibit bifunctional sensing properties, which is in contrast to mechanical flexibility, graphene‐coated flexible field emission displays, crosslinked nanoparticle aggregates as strain gauges, in terms of electrical responses to device bending, and flexible carbon black/polymer composite gas sensors, in terms of tensile bending versus filler content, cyclic loading, and electrode orientation. Very recently, the work by Haick and co‐workers showed interesting gold nanoparticle sensing strips for detecting pressures with high sensitivity, highlighting the application of the nanoparticle materials in pressure sensors and the importance of sintering time to reduce unstable cracks formation.…”

“…The design principle of this unique gauge characteristic is based on the sensitivity of electrical conductivity of molecularly linked nanoparticle network to the interparticle structural changes in terms of device bending and bending orientation with respect to the current flow direction (see Scheme ). Mechanistically, the electronic tunneling or hopping mechanism undergo changes under different strains . A key element of this design principle is the ability to harness the electronic tunneling or hopping by structurally defining the interparticle properties within the thin film‐microelectrode framework.…”

“…Mechanistically, the electronic tunneling or hopping mechanism undergo changes under different strains. [ 5 ] A key element of this design principle is the ability to harness the electronic tunneling or hopping by structurally defi ning the interparticle properties within the thin fi lm-microelectrode framework.…”

An electronic nose on flexible substrates integrated into a smart textile

“…One possibility to circumvent brittle device layers is the use of CPs, which can be strained up to 50% without change in performance [28]. Recent efforts showed the influence of strain on single gas sensors and their performance under bending [26,29].…”