Electrical Transport Mechanisms in Graphene Nanoplatelet Doped Polydimethylsiloxane and Application to Ultrasensitive Temperature Sensors

Abstract

The temperature effect on electronic transport mechanisms in graphene nanoplatelet (GNP) doped polydimethylsiloxane (PDMS) for temperature sensing applications has been investigated under electrical impedance spectroscopy (EIS) analysis. AC measurements showed a very prevalent frequency-dependent behavior in low filled nanocomposites due to the lower charge density. In fact, 4 wt % GNP samples showed a nonideal capacitive behavior due to scattering effects. Therefore, the standard RC-LRC circuit varies with the substitution of capacitive elements by CPEs, where a CPE is a constant phase element which denotes energy dissipation. In this regard, the temperature promotes a prevalence of scattering effects, with an increase of resistance and inductance and a decrease of capacitance values in both RC (intrinsic and contact mechanisms) and LRC (tunneling mechanisms) elements and, even, a change from ideal to nonideal capacitive behavior as in the case of 6 wt % GNP samples. In this way, a deeper understanding of electronic mechanisms depending on GNP content and temperature is achieved in a very intuitive way. Finally, a proof-of-concept carried out as temperature sensors showed a huge sensitivity (from 0.05 to 11.7 °C−1 ) in comparison to most of the consulted studies (below 0.01 °C−1 ), proving, thus, excellent capabilities never seen before for this type of application.

Understanding the role of surface oxygen-containing functional groups on carbon-supported cobalt catalysts for the oxygen evolution reaction

“…One of the factors contributing to the disparity between BET surface area and ECSA was proved to be the distinct electrical conductivity exhibited by various materials. 38 Since carbon-based materials are recognized for their high electrical conductivity, 39,40 there must be factors beyond electrical conductivity that contribute to this discrepancy. Previous studies have shown that the surface chemistry of carbon materials, particularly the presence of OFGs, plays a crucial role in their double-layer capacitance.…”

Toward flexible piezoresistive strain sensors based on polymer nanocomposites: a review on fundamentals, performance, and applications

“…For example, the behavior of PTC-type sensors in PVDF/ AgNW nanocomposites is explained by the volume expansion of the polymer matrix, since it promotes a reduction of electrical contacts between conductive nanoparticles [216,217]. In addition, the PDMS/graphene sensors also indicated PTC behavior by improving phonon/charge carrier dispersion, as well as by reducing the mean free path of charge carriers with increasing temperature [217,218].…”

“…For example, the behavior of PTC-type sensors in PVDF/ AgNW nanocomposites is explained by the volume expansion of the polymer matrix, since it promotes a reduction of electrical contacts between conductive nanoparticles [216,217]. In addition, the PDMS/graphene sensors also indicated PTC behavior by improving phonon/charge carrier dispersion, as well as by reducing the mean free path of charge carriers with increasing temperature [217,218]. However, other nanocomposites revealed NTC-like performance due to the formation of new conductive networks when exposing the nanocomposites to higher temperatures, or due to the nature of the matrix, which can sometimes show increased electrical conductivity due to ion transport [219].…”

“…Distinctive findings emerged, where nonideal capacitive behavior was observed due to scattering effects. Subsequently, the traditional RC-LRC circuit framework underwent alterations as capacitive elements were substituted by constant phase elements, indicative of energy dissipation [166,217]. In addition, the sensitivity to temperature was found to be much higher than the conventional platinum sensors, proving their outstanding capabilities as temperature sensors.…”

Effect of hybrid conductive fillers coating on woven jute fiber and its characterization

“…In recent times, a lot of interest has been shown in GNPs as a potential filler material, which are essentially ultrathin sheets of carbon arranged in a honeycomb-like structure. The GNPs have notable properties such as excellent electrical conductivity (10 7 S m −1 ) [18], high stiffness, superior heat transfer, and a high surface area [19]. Carbon black is also known for its high surface area, lightness, and electrical conductivity (10 2 S m −1 ).…”