Electric noses sensor arrays

These chemosensors represent the simplest of gas sensors in that their chemical reactivity is directly transduced into an electrical signal. Changes in resistance, capacitance, voltage, or current indicate the presence of a particular analyte. These types of sensors are widely used for gas and odor measurements in commercial e-nose sensor arrays. 

While these studies have shown that polyaniline- and polypyrrole-coated fabrics can behave as chemi-resistive sensors, it is also expected that similar chemi-resistive behavior will be achieved using ICP monofilaments and yams, which are woven or stitched into an existing fabric. Ultimately, vapor detection fabric will need to comprise of an array of sensors with the patterned response fed into a microprocessor in order to identify and determine the concentration of the vapor. The relatively low cost of production and subsequent processing of these electrically conductive fabrics provide the opportunity for designing a textile-based electronic nose, which possess built-in massive redundancy for the sensor array so that device will still function even if there is a localized break (rip, tear hole, etc.) in the fabric network. Specifically, in case some area of the sensor system fads, there is a massive redundancy in the garment such that other areas may stdl be able to acquire the information. This will greatly increase the rehabdity of the system. 

It is important that all indicated devices can function at room temperatures. This means that polymer-based sensors have low power consumption (of the order of microwatts) because no heater element is required for their operation. Properties of polymers that influence the operating parameters of sensors can be physicochemical, chemical, optical (photo- and electroluminescence, optoelectronic), redox, hydrophobic/ hydrophilic, piezoelectric/pyroelectric, and electrical (conductivity, resistivity). Moreover, the polymer itself can be modified to bind biomolecules to a biosensor (Mulchandani and Wang 1996). It is mentioned above that polymers have considerable potential for fabrication of multisensing arrays required for e-nose fabrication (Janata and Huber 1985). 

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