Distributed Optical Fiber Sensor Cable for Air Quality (air-sense)

<p>NON-TECHNICAL SUMMARY:<br/> The management of air quality in animal and poultry livestock environments can be challenging, not only due to the required quantitative and qualitative monitoring, but also for determining the air ventilation rates associated with elevated contaminant concentrations at high emission peaks. Ammonia, carbon dioxide, and hydrogen sulfide are generally considered the limiting hazardous gas compounds for animal operations. Elevated levels of air contaminants can cause immediate and long term health effects. Short term effects include eye, nose, or throat irritation, headaches, dizziness, and fatigue. The treatment of short term symptoms can be as simple as isolating the affected person from the contaminated environment. Successive short term exposures, however, can lead to various chronic diseases, including asthma or hypersensitivity pneumonitis.
Long term effects, which usually occur from cumulative exposures over a long period of time, can result in respiratory diseases, heart disease, and cancer, and can be severely debilitating or fatal. Current state-of-the-art sensor systems have limited accuracy and high false alarm rates. They are also hampered by high power requirements, making real-time gas sensor analysis impractical. Conventional mass spectrometric and gas chromatography systems, such as the Trace Gas Analyzer and the Volatile Organic Analyzer, are expensive items whose high power requirements and large mass restrict their use in wide air monitoring applications. Relevant studies on air quality measurements, based on gas chromatography with mass spectrometric detection, have been used to detect and identify odor compounds from manure and livestock facilities, but these types of devices are not amenable to
multi-contaminant detection, specifically in large area, real-time coverage applications. Thus, there is a pressing need for a unique air sensing and monitoring approach that can quickly and continuously detect and measure concentrations of a variety of gases, at a reasonable cost, and over a wide area. In response, we propose to develop Air-Sense, a high performance, reliable, wide area monitoring system that will be able to conduct simultaneous real-time multi-analyte monitoring with a minimal number of components to meet the air quality guidelines for livestock and animal operations. This will be achieved by developing a distributed optical fiber sensor cable containing multiple sensor fibers for ammonia, hydrogen sulfide, and carbon dioxide in one cable embodiment. Each sensor fiber will consist of a core fiber coated with a colorimetric sensor indicator immobilized in a highly
permeable polymer optical cladding. As the sensor fiber is exposed to the target gas, the cladding color will change, and hence affect the light attenuation accordingly. An optical readout module with integrated software and signal processing algorithms will send an alarm when hazardous gas emissions are elevated above 10 percent of Immediately Dangerous to Life or Health (IDLH) levels, and ventilation is required. The sensor cable will allow for multiple sensor detection, thereby adding redundancy to the monitoring process.<p>
APPROACH: <br/>The Air-Sense system will feature a suite of cabled sensor fibers that will integrate multiple chemical sensor claddings into a single cable. The work is based on a sensing methodology previously developed by our company for the detection of chemical warfare agents (and more recently, for the long term monitoring of trichloroethylene in groundwater), called Distributed Intrinsic Chemical Agent Sensing and Transmission (DICAST). The key advantage of our unique innovation lies in the integrity and low complexity of the sensor, which is accomplished by using a single cable that integrates various optical fiber sensor channels, hence reducing the electronics count relative to the current approach of using arrays of discrete sensors (with different operating principles). The incorporation of multiple sensor fibers in the proposed cable format for the detection
of various gases will have negligible effect on the system weight and size considerations. The sensor suite will allow data to be conveyed from the sensor fiber segments using various communication protocols, including WiFi, and will be used to activate semi-autonomous mechanisms. These mechanisms would include controls for changing the atmospheric content, and more importantly, for providing an early warning. The optical-based technology provides additional advantages, such as immunity to electrical noise, ease of miniaturization, safe use near flammables, and the durability of polymer matrices. The data obtained will allow us to report the performance of the integrated device as dictated by its Receiver Operating Characteristic. We will combine our experience with the large knowledge base that exists for polymer coatings so that we can include innovative manufacturing methods, (e.g.,
ultraviolet polymer curing and batch reactors), to reduce cost. In Phase I, we will identify and develop sensor materials, in the form of thin film claddings, for carbon dioxide and ammonia. This effort will include identifying the optimum indicator for each analyte in terms of sensitivity to their target analyte. Various porous optical fiber cladding properties, such as target gas diffusion, cross-linking density, and miscibility with the indicator chemistry, and potential environmental effects, such as temperature and humidity, will be evaluated. In Phase II, we will optimize the Phase I sensor elements, design and fabricate the system optical readout module, integrate the software and signal processing algorithms with the reader, and extend the detection capability of the sensor cable to include hydrogen sulfide. The ability to generate robust versions of all of the sensor chemistries
will be evaluated in Phase II. The optoelectronic components and control module developed by our company in earlier work for the DICAST sensor cable will be adapted to the sensor elements needed for the Air-Sense monitor. Additionally, cross-interference between multiple sensor channels will determine the need for a pattern recognition neural network. By the end of Phase II, we will have prototyped a low cost and distributed optical fiber air contaminant monitor for production, installation, and commercialization in Phase III.
</p> <p>PROGRESS: <br/>2011/07 TO 2012/02 <br/>OUTPUTS: Colorimetric indicators for the detection of ammonia and carbon dioxide were evaluated for sensitivity, response time, reversibility, polymer miscibility, and aging stability. These indicator chemistries were immobilized into UV-curable polymeric claddings that were selected based on cross-linking density, mechanical properties, refractive index (lower than a glass core fiber refractive index of 1.45), and indicator compatibility, and coated onto glass microscope slides as a preliminary form of the fiber cladding material. The target indicator was dissolved in an appropriate solvent, then mixed with the polymer at 80%-90% solids, spin-coated onto a glass microscope slide, and cured by UV radiation or heat. The cured films were then tested in a gas-tight flow cell coupled with a light source and photodetector with optical
fibers. The selected indicators were optimized via polymer matrix evaluation, the addition of free volume enhancers to increase gas diffusion, and the addition of antioxidant additives to enhance sensor stability and shelf life. The optimized sensor claddings were calibrated by exposing them to a step-up ladder of ammonia or carbon dioxide in a humidified air stream. Collaboration with Professor Larry Jacobson of the Department of Bioproducts and Biosystems Engineering at the University of Minnesota (UMN) enabled us to perform preliminary field testing of the selected sensor formulations, and establish their response characteristics. The sensors were tested with the same air flow used by UMN to monitor barn air quality before and after filtration. A semi-continuous sampling system was used to collect air samples from the intake and output of two biofilters (flat-bed and A-frame) located
at UMN's West Central Research and Outreach Center in Morris, MN. These biofilters treat 100% of the ventilating air from two nursery rooms capable of housing 288 pigs. Aging studies were performed by placing the sensor film cladding samples near the duct where the barn air is pumped through. Sensor dependence on variable environmental conditions such as relative humidity and temperature was also calibrated. Based on these findings, we created a system outline, and identified the optoelectronic system components. Extensive outreach efforts to potential end users and commercial partners based on the laboratory and field testing performance resulted in great interest from SKOV A/S (Denmark), one of the world's leading specialists in ventilation systems for livestock operators around the world, and MSA, a billion-dollar U.S. company competing worldwide in the industrial safety and first
responder sectors. Both companies have provided us with products specifications, including performance requirements, mechanical enclosures, and electronic interfaces, to enable us to dovetail our technology with their products. The results of our work were presented in April 2012 at the Europt(r)ode XI Conference on Chemical Sensors and Biosensors in Barcelona, Spain.? PARTICIPANTS: Manal Beshay, Chemical Sensor Scientist, served as the Principal Investigator and Project Director of this project. Ms. Beshay received an M.Sc. in Inorganic Analytical Chemistry with emphasis on supra molecular chemistry in molecular recognition and drug delivery from the University of Alexandria, Egypt in 2000. Prior to joining Intelligent Optical Systems in 2003, she has been a Quality Assurance Chemist for the Coca-Cola Company, performing quality and sensory tests on raw materials and finished
products, and judging product acceptability by comparison to specifications. Ms. Beshay has extensive expertise in optical sensor development, specifically in chemical gas detection and monitoring applications. She has led the chemistry team for the development of DICAST, a distributed intelligent chemical agent sensing and transmission system that is capable of monitoring chemical warfare agent intrusions in military, government, and civilian facilities. Although Air-Sense development is based on DICAST technology, Air-Sense operates on a principle in which the indicators are designed to be simultaneously responsive and reversible, rather than act a detection system for a sudden chemical release. Ms. Beshay serves as the PI on a number of related projects for optical chemical detection in the gas and aqueous phases for monitoring and detection applications. In this project Ms. Beshay
was responsible for the overall direction of the project, including sensor design, optical approach, testing, system integration and project management and reporting. Jesus Delgado Alonso, Senior Scientist, received a Ph.D. in Organic Chemistry from the Universidad Complutense de Madrid, Spain in 2000. He has over 15 years of experience in indicator dye design, synthesis, and structural and photochemical characterization, and has extensive experience in instrument development for chemical monitoring. In this project Dr. Delgado Alonso developed and optimized the indicator sensor chemistries, and managed the day-to-day sensor experiments. Sajid Wasif, Chemist, received his B.Sc in Bioengineering with emphasis in cell and tissue, nano and biomaterials, chemistry, and biology from the University of California, Los Angeles in 2010. In this project, he optimized the sensor formulations and
conducted the day-to-day testing. Mr. Wasif also played a key role in the field testing of the sensors at the University of Minnesota, including sample preparations, optical and mechanical setup assembly, and data collection and correlation. Collaboration was established with Professor Larry Jacobson of the Department of Bioproducts and Biosystems Engineering at the University of Minnesota (UMN). This collaboration enabled us to perform preliminary field testing of the selected sensor formulations at UMN's West Central Research and Outreach Center to establish response characteristics. Participation in the Purdue University/USDA program ""Building a Commercialization Plan"" was instrumental in developing a marketing plan for Air-Sense technology, and subsequently establishing a relationship with commercial sensor companies MSA and SKOV A/S. TARGET AUDIENCES: The primary target market for
Air-Sense is manufacturers of sensors for livestock ventilation systems, to provide a reliable and effective means of monitoring air quality in animal feeding and nursery environments in order to improve animal health, reduce worker exposure to high levels of gas, and reduce power consumption for unnecessary ventilation. The broader, secondary target market includes manufacturers of gas sensing and detection systems for a wide range of industries requiring real-time, continuous, multi-contaminant gas detection over large areas. Technical discussions with sensor manufacturers indicate that optical-based sensing technology can be deployed for mine safety, fire service, law enforcement, construction, oil and gas, chemical, and other industries, as well as the military. We contacted approximately 25 companies specializing in livestock ventilation, safety sensing and detection systems, and
sensor manufacturing to discuss the Air-Sense technology. SKOV A/S and MSA in particular expressed a keen interest in the technology under development. SKOV A/S is a leading supplier of ventilation and automatic systems for the agriculture industry. The company develops, produces, and markets capacitive and climate sensors under the DOL Sensors brand for use in food production, animal feed, food processing, food transport and storage. SKOV has expressed an interest in establishing an immediate commercial relationship with us, wherein we will supply SKOV with Air-Sense technical performance characteristics as we advance through the development steps, and identify the system's mechanical and electronic interface parameters to ensure compatibility with their current monitoring platforms. MSA is a leading supplier of portable gas detection instruments for safety monitoring in industrial
applications. MSA envisions supporting our development via periodic consulting on design and specification requirements that can meet MSA's industrial sensing criteria. Both companies have provided us with products specifications, including performance requirements, mechanical enclosures, and electronic interfaces, to enable us to dovetail Air-Sense technology with their products. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.</p>