Complex, multi-analyte vapor analysis is routinely achieved using laboratory tools such as gas chromatography combined with mass spectrometry (GC-MS). However, these systems are not readily configurable for compact, low- concentration, near real-time environmental tracking of vapors (e.g. a wearable data logging badge), which is a stated technology development goal of the National Institute of Environmental Health and Safety (NIEHS). To address this need, Nanohmics Inc., an early-stage technology development company (Austin, TX) is currently developing OmniScense detection technology, a low profile, vapor-phase environment analysis device for monitoring air quality and toxicity at levels that are pertinent to environmental health and safety. Prototype OmniScensor devices developed to date have been used to identify and quantify common solvents and other volatile organic compounds (VOCs) via direct electrical detection with chemiresistive metal oxide semiconductor (MOx) arrays patterned using the method of NanoImprint Lithography (NIL). This approach provides greater vapor component selectivity and quantification capabilities over a large concentration dynamic range by controlling the dimensions of the sensor element at the nanoscale. Dimensional control is not readily achieved with existing commercial MOx thin films, or with research platforms based on composite transducers (e.g. nanowires, nanotubes, metal nanoparticles and graphene). In addition to sensor feature size control, further surface derivatization will provide a means to discriminate chemically similar vapor species (e.g. nonpolar toluene, xylene and hexane), thereby enabling complex analysis across the broad set of chemical functionality ranging from highly polarizing carrier acceptors/donators to nonpolar volatile gases/organics.
Volatile organic compounds (VOCs) are known to have long-term adverse effects on human health and well-being when present in the workplace environment (e.g. during industrial/chemical manufacturing). The ability to quantify an individual's exposure to hazardous or toxic environmental compounds at the point of contact as well as track exposure from source to dose is an important mission of the National Institute for Environmental Health and Safety (NIEHS). In order to assess the causal relationship between exposure and biological/physiological toxicity, new compact measurement systems that employ methods for quantification of complex mixtures are needed to track potentially harmful vapor compounds and assess the relationship between point-of-contact exposure to long-term biological/physiological effects. The critical barrier for development of such a low profile vapor environment monitoring device are the introduction of solid-state transducer arrays that can collect transient dose responses and analysis the profile without requiring slow voluminous processes such as chromatography columns and associated vacuum detectors necessary for methods such as mass spectrometry. Solid-state sensor arrays prepared in this fashion and in combination with read-out electronics, vapor sampling front-end hardware, analysis software and a power source can lead to low-profile, vapor environment monitoring systems that can be used to study the impact of exposure on human biology. These systems will be useful in a number of safety, security, surveillance and diagnostic applications and include the ability to track long-term vapor exposure against population-based (epidemiological) research.
