Detection of hydrogen sulfide

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Background: Hydrogen sulfide (H2S) is a corrosive, toxic, inflammable and odoriferous chemical that causes safety concerns. The threshold limit value (THL) and the recommended exposure limit (REL) of H2S are both set at 10 ppm, and it is life-threatening when exceeding 300 ppm. In addition to public safety, H2S can affect personal and social communications. Presence of this chemical in breath at concentrations of 300 ppb and higher is responsible for halitosis (bad breath).  Detection of H2S is therefore important for applications in industrial monitoring, personal safety, and the medical field. Commercially available H2S detectors are often based on electrochemical methods or specific spectroscopic techniques, while solid-state resistivity-based sensors can offer certain advantages for development of portable and low-cost H2S detectors.    Technology: This invention describes the detection of hydrogen sulfide (H2S) gas using carbon nanotube-based chemical sensors. Single-walled carbon nanotubes (SWNT's) are functionalized with different nanomaterials and nanostructures to develop portable, solid-state hydrogen sulfide detectors.   Applications: * Detection of hydrogen sulfide gas   Advantages: * Small size: portable detector and easy to be incorporated into sensor arrays * Uses a simple circuit * Operates at room temperature, no additional heating element is needed * Low power consumption * Solid-state device: no electrolyte needed * Low cost: lead to potentially disposable product * No cross-sensitivity for specific applications * Low detection limit