Selective detection of naphthalene with nanostructured WO<sub>3</sub> gas sensors prepared by pulsed laser deposition

Abstract

Abstract. Pulsed laser deposition (PLD) at room temperature with a nanosecond laser was used to prepare WO 3 layers on both MEMS microheater platforms and Si/SiO 2 substrates. Structural characterization showed that the layers are formed of nanoparticles and nanoparticle agglomerates. Two types of layers were prepared, one at an oxygen partial pressure of 0.08 mbar and one at 0.2 mbar. The layer structure and the related gas sensing properties were shown to be highly dependent on this deposition parameter. At an oxygen pressure of 0.2 mbar, formation of ε-phase WO 3 was found, which is possibly contributing to the observed increase in sensitivity of the sensor material.The gas sensing performance of the two sensor layers prepared via PLD was tested for detection of volatile organic compounds (benzene, formaldehyde and naphthalene) at ppb level concentrations, with various ethanol backgrounds (0.5 and 2 ppm) and gas humidities (30, 50 and 70 % RH). The gas sensors were operated in temperature cycled operation. For signal processing, linear discriminant analysis was performed using features extracted from the conductance signals during temperature variations as input data.Both WO 3 sensor layers showed high sensitivity and selectivity to naphthalene compared to the other target gases. Of the two layers, the one prepared at higher oxygen partial pressure showed higher sensitivity and stability resulting in better discrimination of the gases and of different naphthalene concentrations. Naphthalene at concentrations down to 1 ppb could be detected with high reliability, even in an ethanol background of up to 2 ppm. The sensors show only low response to ethanol, which can be compensated reliably during the signal processing. Quantification of ppb level naphthalene concentrations was also possible with a high success rate of more than 99 % as shown by leave-one-out cross validation.

Pulsed Laser Deposited Films for Microbatteries

“…Highly transparent WO 3 films exhibiting strong coloration and fast and full bleaching were prepared under PLD conditions (Φ = 1 J·cm −2 , T s = 250 • C, P O 2 = 16 Pa, and d = 40 mm) [252]. WO 3 films were also prepared using similar PLD parameters for applications in gas sensors [253][254][255].…”

Highly Sensitive and Selective VOC Sensor Systems Based on Semiconductor Gas Sensors: How to?

“…This integrated approach is at the core of the EU project SENSIndoor [60] addressing indoor air quality and demand controlled ventilation based on sensor systems placed in each room, i.e., offices, living and sleeping rooms, public buildings, transport, etc. On the one hand, the approach is used for optimization of the sensor elements themselves, i.e., based on novel nanotechnology approaches such as Pulsed Laser Deposition (PLD) and novel sensor materials [23,24,[61][62][63][64]. On the other hand, extensive field tests are required which include reference tests based on existing standards.…”

“…However, so far no rigorous study has proven that MOS nanowires or carbon nanotubes in fact achieve superior sensitivity compared to standard granular materials. Novel manufacturing methods for metal oxide layers, especially Pulsed Laser Deposition [23], achieve highly porous sensor layers with well-controlled morphology that can even reach high selectivity for some relevant target VOCs such as naphthalene [24].…”

DAV<sup>3</sup>E – a MATLAB toolbox for multivariate sensor data evaluation

“…This dataset is publicly available (Graham and Oppacher, 2018) from the UCI machine learning repository (Lichman, 2013). It consists of a training set with 606 observations, i.e., cycles, with 100 data points each, and a test set with the same dimensions.…”