Fluctuation-enhanced sensing with organically functionalized gold nanoparticle gas sensors targeting biomedical applications.

TLDR: Results on formaldehyde detection using fluctuation-enhanced gas sensing showed that formaldehyde was easily detected via intense fluctuations of the gas sensor's resistance, while the cross-influence of ethanol vapor was negligible.

About: This article is published in Talanta.The article was published on 2016-11-01 and is currently open access. It has received 12 citations till now. The article focuses on the topics: Breath gas analysis.

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Figure 4. (a) Time-dependent voltage fluctuations u(t) across a gas sensor of resistance R = 280 kΩ upon its exposure to synthetic air at a bias voltage UB of 7.5 V; the sensor was connected in series with a resistance of 660 kΩ as shown in the circuit diagram. (b)

Figure 3. (a) Time-dependent voltage fluctuations u(t) across a gas sensor of resistance R upon its exposure to formaldehyde vapor at a bias voltage UB of 11.3 V; the sensor was connected in series with a resistance of 390 kΩ as shown in the circuit diagram. (b) Power spectral density Sr(f ) of the sensor’s resistance fluctuations, multiplied by frequency f and divided by the square of the sensor’s DC resistance (246 k), upon exposure to the shown gases at a bias voltage UB of 11.3 V. (c) Distribution of voltage fluctuations, with standard deviation , across the sensor upon its exposure to the shown gases at a bias voltage UB of 11.3 V (also see the main text). (d) Power spectral density Sr(f ) of the sensor’s resistance fluctuations, multiplied by frequency f and divided by the square of the sensor’s DC resistance (526 k), upon exposure to the shown gases at a bias voltage UB of 5 V.

Figure 2. Current–voltage (I–U) characteristic of the investigated gas sensor operated at room temperature (22C) in synthetic dry air.

Figure 1. (a) Schematic representation of the AGD equipment used for ultra-pure AuNP synthesis. (b) SEM image (top view) of a layer of AuNPs functionalized with 2-mercaptobenzoxazole. (c) XPS spectrum for a layer of functionalized AuNPs.