VOCs sensors

COz sensors are suitable for living rooms, offices and bedrooms, whereas for bathrooms (main parameter humidity) and kitchens (main parameter smell ) other non-specific sensors may be used. Therefore combinations of different sensors like humidity sensors, smelF-sensors (unspecific VOC-sensors) and presence sensors could be the best solution. A simple movement detector with an additional manual override (ventilation on/off for a predetermined time) could be a low-cost alternative. 

Figure 12.8-10. Schematic drawing of the prototype unit design 1 showing the locations of the temperature, humidity and total VOC sensors.

Tchoupo, G. N. Guiseppi-Elie, A., On padern recognition dependency of desorption heat, activation energy, and temperature of polymer-based VOC sensors for the electronic NOSE, Sensors and Actuators B-Chemical 2005, 110, 81-88. 

A.M. Taurino, S. Capone, P. Siciliano, T. Toccoli, A. Boschetti, L. Guerini, S. lannotta, Nanostructured Ti02 thin films prepared by supersonic beams and their application in a sensor array for the discrimination of VOC , Sensors and Actuators B, 92, 292-302, (2003). 

Traces of VOCs in human breath can be a symptom of diabetes, kidney failure, asthma or breast cancer. VOCs were mainly detected by mass spectroscopy with a ppb detection limit. The most advanced VOC sensor based on SWCNTs for medical application was introduced by Peng et al. (2008a, 2008b). This device is designed as an array of ten SWCNT chemiresistors coated with different non-polymeric organic layers. Since the responses of each chemiresistor are different, a principal component analysis of the measurement allows the direct discrimination between a healthy patient and a patient with cancer or renal diseases. The same authors have also highlighted the dramatic effect of humidity on the sensor response and have proposed coupling the device with a water extractor (Fig. 10.8). 

T. Itoh, I. Matsubara, W. Shin, and N. Izu, Synthesis and characterization of layered organic hybrid thin films based on molybdenum trioxide with poly(N-methylanihne) for VOC sensor. Mater. Lett., 61, 4031 034 (2007). 

Experimental studies have shown that the above-mentioned features of metal nanoparticles really may be applied in sensor technology, and, by exploiting these nanoscale properties, a highly efficient gas sensor can be designed and fabricated (Shipway et al. 1999 Ahn et al. 2004 Raschke et al. 2004 Drake et al. 2007 Dovgolevsky et al. 2009 Saha et al. 2012). In particular, metal nanoparticles can be incorporated in optical hydrogen and VOCs sensors (Cioffi et al. 2002 Ahn et al. 2004 Filenko et al. 2005). 

Schollhorn et al. 1998 Ceyhan et al. 2006) (see Table 10.2). For explanation of MPc gas sensitivity the approach based on gas molecule interaction with the Ti-electron network of the phthalocyanines is normally used (Roisin et al. 1992). For example, in the case of VOCs sensors the VOCs would play an electron acceptor role. When the VOC molecules interact with the 7i-electron network of the phthalocyanines, it causes the transfer of an electron from the phthalocyanine ring to the VOC molecule (Schollhorn et al. 1998). Thus, the induced positive holes on the film surface give rise to an increase in the p-type conductivity of the film. 

Rodriguez A, Amirola J, Milldn M, Horrillo MC, Sayago I, Garcia M, Gutiirrez FJ (2004) Electromechanically coupled feedback loops for microsystems. Application to volatile oiganic compounds (VOC) sensors. In Proceedings of the 3rd IEEE conference on sensors, IEEE sensors, vol 1. Vienna, Austria, 24-27 Oct 2004, pp 154—157... 

BAPI s VOC Sensors detect hundreds of air contaminants, providing a more complete measure of air quality for appropriate ventilation. 

Even in their earliest stages of development, wireless sensor networks include already radio-frequency transceivers soil, water, ion, and VOC sensors global positioning sensors microcontrollers and power sources. See Chap. 14 of second volume for VOC sensors. 

Three types of materials, metal oxide semiconductors such as ZnO and SnOa, conducting polymers such as polyanUine and polypyrrole, and carbon-based materials such as carbon nanotubes (CNTs) and graphene, have shown significant performance benefit for the development of 1-D- and 2-D-based sensors for VOCs (Table 14.3). Until recently, the development of 1-D nanostructure-based VOC sensor using the abovementioned materials was slow because of challenges in the synthesis and fabrication of these nanostructures with controlled dimensions, morphology, and purity. 

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