Gold Nanoparticle Chemiresistor Sensors:  Direct Sensing of Organics in Aqueous Electrolyte Solution

Abstract

A novel chemiresistor sensor for detection of organic analytes in high-conductivity aqueous electrolyte solution is reported. The chemiresistor sensor is based on thin films of gold nanoparticles capped with a 1-hexanethiol monolayer that is inkjet printed onto a microelectrode. In order for a change in nanoparticle film resistance to be measured, the electronic conduction must preferentially occur through the nanoparticle film rather than through the high-conductivity electrolyte solution. This was achieved by miniaturizing the chemiresistor device such that the double layer capacitance of the electrodes in contact with the electrolyte solution gives rise to a significantly larger impedance compared to the nanoparticle film resistance. This system was shown to be sensitive to simple organics dissolved in an aqueous electrolyte solution. The organic analytes, dissolved in the aqueous solution, partition into the hydrophobic nanoparticle film causing the nanoparticle film to swell, resulting in an increase in the low-frequency impedance of the sensor. An increase in the impedance, at 1 Hz, of the gold nanoparticle chemiresistor on exposure to toluene, dichloromethane, and ethanol dissolved in 1 M KCl solution was demonstrated with detection limits of 0.1, 10, and 3000 ppm, respectively. Titration curves over 3 orders of magnitude could be obtained for analytes such as toluene.

Barium alginate caged Fe3O4@C18 magnetic nanoparticles for the pre-concentration of polycyclic aromatic hydrocarbons and phthalate esters from environmental water samples

“…Among them SPE is the most popular one in environmental analysis for its high extraction efficiency, low consumption of organic solvents and easy operation. Nanomaterials, which possess nanosized diameter and large surface area, are being applied in numerous scientific fields [1][2][3][4]. In this regard many research groups have developed various types of nanosized SPE sorbents [5][6][7][8][9][10][11][12].…”

Scatter-limited conduction in printed platinum nanofilms

“…The active electronic inks that are deployed in such material printers range from insulators to metals and typically face a number of challenges to ensure that design features may be accurately reproduced whilst the electronic performance remains acceptable [3]. Popular metal inks generally comprise a suspension of nanoparticles which must be dried and sintered at high temperatures to achieve an acceptable resistivity for interconnect features [4][5][6]. These suspension inks frequently suffer from undesirable agglomeration effects which may lead to nozzle blocking and ultimately a limitation on the achievable resolution of printed features.…”

“…Significant effort has recently been reported on the development of printable gold inks [4][5][6]11] which have important applications as chemiresistor sensors and as electrode structures that possess a high chemical stability for lab-on-chip devices [14]. Compared to the advances made in the optimisation of gold inks relatively less progress has been reported for printed platinum (Pt) despite such films having potentially novel applications for biosensor and fuel cell technologies.…”

Influence of Gold Nanoparticle Film Porosity on the Chemiresistive Sensing Performance

“…Gold nanoparticle-based chemiresistors have shown to be versatile gas-phase [1][2][3][4][5][6][7][8][9][10] and liquid-phase [11] sensor systems. The chemiresistors function by a change in electrical resistance of the gold nanoparticle films by the partitioning of analytes into the organic caps surrounding the nanoparticles [12,13].…”

“…From the perspective of chemical sensing, we are interested in determining the porosity of gold nanoparticle films that are used as chemiresistive materials in liquids [11,13,[30][31][32][33][34][35][36]. The assembly of multilayered gold nanoparticles produces a disordered porous film [37].…”