Thiol-functionalised gold nanoparticle chemiresistors can respond to low-molecular weight chemicals through changes in electrical resistance. This low-cost sensor technology is currently being developed for multiple applications including water quality control, microbial metabolomics, and point-of-care disease diagnostics. Recently, we have shown that by introducing a gate electrode into the design of the chemiresistor, a new and improved chemiresistor can be formed that is highly sensitive towards charged organic species. Given the importance of charged biological, pharmaceutical, pesticide and herbicide molecules, this could significantly broaden the applicability of gold nanoparticle chemiresistor sensors. A gate electrode placed in electrolyte solution can selectively drive hydrophobic cations or anions into the nanoparticle film depending on the gate polarity. The preconcentration of the charged species into the nanoparticle film, through application of a gate potential, leads to an increased interparticle separation (film swelling) and thus a large electrical resistance change. As proof-of-concept, ibuprofen, a negatively-charged anti-inflammatory drug, was detected at levels 250 times lower than with a standard chemiresistor. The gate-controlled gold nanoparticle chemiresistors have practical implications for improving the sensitivity towards charged molecules by several orders of magnitude, as well as being able to distinguish between molecules that are neutral, positively or negatively charged. Figure 1. <img src='https://acs-archive-assets2.s3.amazonaws.com/241nm/uploads/66865_bmc_ken_figure.jpg' alt='' /> Fig. 1. Response of a standard gold nanoparticle chemiresistor and gated gold nanoparticle chemiresistor on exposure to 5 �M ibuprofen at t = 80 s.

Ultrasensitive gold nanoparticle chemiresistor sensors with gate control

248th National Meeting (2014)

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