Au/conducting polymer volatile organic compounds (VOC) sensors based on oxidative chemical vapor deposition (oCVD)
Xiaoxue Wang and Karen K. Gleason
Sponsorship: Shell company
Volatile organic compounds (VOCs) are important hazards in petroleum industry. Hazardous chemicals such as hydrocarbons and alcohols may lead to explosions in refinery1. However, current methods to detect VOCs, such as metal oxide sensors and infrared chemical detectors, require high fabrication temperature, high operation temperature, complicated fabrication methods or high cost. Therefore, it is important for industry to develop an economic and efficient way to detect VOCs. At the same time, incorporating the chemical sensors into wireless sensor network is an emerging trend2. Here, we demonstrate a room temperature gold nanoparticle-conducting polymer composite sensor for the application in wireless sensor network. Conducting polymer poly(3,4-ethylenedioxythiohene-co-3-thipheneacetic acid) (poly(EDOT-co-TAA)) is deposited on printed circuit boards(figure 1 (a)) using oxidative chemical vapor deposition(oCVD)3 technology. Wet chemistry4 was used to covalently tether gold nanoparticles via a linker molecule on the copolymer film(figure 1(b)). The hybrid film of gold nanoparticles and copolymer film was characterized by scanning electron microscopy (SEM)(figure 1 (c)), UV-vis, FTIR and XPS. The resistive response was defined as (R-R0)/R0 *100%. We tested the response of these sensors to methanol (figure 1(d)), water, acetone and toluene. The selectivity of methanol over acetone and toluene is demonstrated. With simple fabrication method and low cost, our sensors respond to VOCs with fast and high response. In addition, fabricated under a mild temperature, our sensor is capable to be directly deposited on printed circuit boards for a sensor network. The operating temperature of our sensor is room temperature, which provides safe and energy efficient detection of VOCs.
Figure 1 (a) the printed circuit board used in this sensor; (b) the chemical structure of the conducting copolymer, and the gold nanoparticle covalently linked on the polymer thin film; (c) SEM image for the Au-polymer composite; (4) the resistive response to methanol vapors.
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4. Vaddiraju, Sreeram, and Karen K. Gleason. Nanotechnology 21.12 (2010): 125503.