Source: SEACOAST SCIENCE, INC. submitted to NRP
A NOVEL, LIGHTWEIGHT AMMONIA VAPOR DETECTOR
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
Reporting Frequency
Annual
Accession No.
1028762
Grant No.
2022-33610-37532
Cumulative Award Amt.
$650,000.00
Proposal No.
2022-04364
Multistate No.
(N/A)
Project Start Date
Sep 1, 2022
Project End Date
Feb 28, 2025
Grant Year
2022
Program Code
[8.4]- Air, Water and Soils
Recipient Organization
SEACOAST SCIENCE, INC.
2151 LAS PALMAS DR, STE C
CARLSBAD,CA 920111575
Performing Department
(N/A)
Non Technical Summary
Background: Chemicals released from agricultural and industrial waste are major contributors to air and water pollution, both domestically and globally. This is especially true of ammonia (NH3), a colorless, pungent gas that forms as a byproduct of agricultural waste, and is commonly found in cleaning agents used in commercial agricultural and industrial settings. Ammonia gas is a significant hazard to human health, livestock, and crops, with the severity of health effects largely dependent upon the dose, duration, and exposure route. In the presence of water, ammonia can convert to ammonium hydroxide which is strongly corrosive and toxic. Contact with small amounts of ammonia can cause serious damage to the eyes and respiratory tracts of both humans and livestock, while exposure to larger amounts of ammonia gas can cause blindness and/or permanent lung damage. OSHA has set a 50-ppm limit for ammonia exposure over an 8-hour work day, and the EPA considers 300 ppm exposure to be immediately threatening to human life.Need: Today, accurate measurements of ammonia pollution are exceedingly difficult to collect in agricultural environments. As a result, the sources of ammonia generation and its subsequent diffusion behavior are more difficult to pinpoint, and the true output of ammonia pollution is frequently underestimated. Understanding ammonia pollution can have critical impacts on the health and sustainability of agricultural enterprises. A consequence of ammonia poisoning in many farms is a pervasiveness of unhealthy animals with respiratory diseases, which can render them unsafe for human consumption, and lowering farm profitability. In recent years, agricultural enterprises have placed increasing emphasis on reducing ammonia vapors to ensure livestock live in clean and healthy conditions. This trend is also supported by many health-conscious consumers willing to support farms that maintain safe and healthy living conditions for their livestock, to ensure the food they consume is at its highest quality. These consumers are increasingly loyal supporters of "clean" farms and are willing to pay a premium for nutritious, high-quality food.Improving the capacity to analyze and mitigate the environmental risks of ammonia pollution in both farms and processing factories is paramount. Analytical instruments which can quickly identify environmental factors that amplify or accelerate the accumulation of toxic ammonia vapors into the environment (i.e. improper waste management, fertilizer overuse, etc.) are needed to develop rational measures to minimize air, water, and soil pollution and toxic exposure. Unfortunately, today's commercially available ammonia gas detectors rely on expensive, antiquated technology which limits their utility. For example, the more accurate ammonia detectors, such as the Boreal and Nonplus Lasers, are prohibitively expensive (~$30-$40K) for most farms. Electrochemical Cells such as the GG-NH3 from Calibration Technologies are also rather expensive ($1,200/unit) and do not perform well in outdoor settings.Currently, there are no low-cost, user-friendly ammonia vapor detection methods capable of remotely monitoring and reporting reliable real-time measurements. Moreover, despite the known advantages of wireless connectivity, most ammonia detectors lack the functionality to be connected to a multi-node wireless detection network. These limitations indicate that there is a clear lack of affordable and efficient options to monitor ammonia pollution across 3-dimensional landscapes in real-time. Consequently, comprehensive topographical assessments of ammonia diffusion which might inform mitigation practices are exceedingly difficult to collect.Value Proposition: Seacoast Science proposes the development of a rugged, lightweight, ammonia detector, that fills the current void in commercial detection capabilities by offering an affordable and versatile solution to accurately monitor ammonia pollution across a diverse array of agricultural environments. Seacoast's proposed detector will monitor and quantify the concentration and spatial diffusion of gas-phase ammonia in real-time, maintain a record of the cumulative vapor load, and wirelessly transmit this data to a personal computing device for analysis via user-friendly software that can be operated with minimal training. The proposed detection technology is based on the use of ammonia-sensitive Lewis Acid Telechelic Polymers (LATPs) as chemical transducers in Micro-Electro-Mechanical-Systems (MEMS) chemicapacitor and chemiresistors. The proposed detector will feature an inexpensive, semi-disposable sensing element, strategically designed to be replaced periodically to ensure high operational performance while extending device lifetime. Furthermore, the system's wireless capabilities will enable each sensor to function as a node in an integrated wireless detection network. The proposed detector is engineered to be a cost-effective, frontline protective measure against exposure to ammonia vapors; with advanced features capable of meeting the increasing demand for improved air quality and safety from hazardous gases.
Animal Health Component
25%
Research Effort Categories
Basic
25%
Applied
25%
Developmental
50%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
1330410200050%
3140410200050%
Goals / Objectives
Seacoast Science, Inc. (Seacoast) is developing a rugged, lightweight, ammonia (NH3) detector, that fills the current void in commercial detection capabilities by offering an affordable and versatile solution to accurately monitor ammonia pollution across a diverse array of agricultural environments. Seacoast's NH3 detector will monitor and quantify the concentration and spatial diffusion of gas-phase ammonia in real-time, maintain a record of the cumulative vapor load, and wirelessly transmit this data to a personal computing device for analysis via user-friendly software that can be operated with minimal training. The NH3 detection technology is based on the use of ammonia-sensitive Lewis Acid Telechelic Polymers (LATPs) as chemical transducers in Micro-Electro-Mechanical-Systems (MEMS) chemicapacitor and chemiresistors. The NH3 detector will feature an inexpensive, semi-disposable sensing element, strategically designed to be replaced periodically to ensure high operational performance while extending device lifetime. Furthermore, the system's wireless capabilities will enable each sensor to function as a node in an integrated wireless detection network. The proposed device is engineered to be a cost-effective, frontline protective measure against exposure to ammonia vapors; with advanced features capable of meeting the increasing demand for improved air quality and safety from hazardous gases.Seacoast's ammonia detection development is directly related to the USDA FY2021 SBIR Research topic 8.4 - Conservation of Natural Resources. Specifically, this NH3 detector addresses the USDA Special Research Priority for Air Resources which seeks the development of new and improved technologies to monitor air quality and reduce agricultural air pollution.Potential impact of the research: Seacoast's NH3 detector will be used by agricultural and industrial sites seeking to improve waste management and fertilizer use to mitigate the harmful effects of NH3 pollution. The current industry standard for NH3 vapor detection involves passive detection using expensive lasers, or electrochemical detectors which perform poorly outdoors, or contracting outside testing services, all of which significantly under-sample NH3 vapor and provide inadequate spatial and temporal data to comprehensively monitor diffusion of ammonia pollution. Currently, there are no low-cost, user-friendly direct NH3 vapor detection methods capable of monitoring and wirelessly reporting real-time measurements of NH3 levels (ie. intensity, duration, location, and cumulative load), which may reasonably be operated by non-technical personnel. The proposed detector will come equipped with the full array of adv. features needed to affordably mitigate NH3 pollution.Seacoast's detector will provide low-cost, real-time, quantitative measurements to enhance decision support for responsible and sustainable ammonia mitigation and remediation efforts. The proposed device is anticipated to help reduce the risk of agricultural, industrial, commercial, and/or residential exposure to toxic NH3 gas. Furthermore, this tool will allow agricultural enterprises (industrial farms, processing factories, etc.) become more aware of the impact of agricultural waste management and fertilizer use, for example, alerting farmers to hazardous diffusion of NH3 vapor from waste byproducts on their farms when may harm their staff, livestock, or crops.In Phase I we sought to demonstrate, as proof-of-concept, that the proposed LATP chemistry and integrated MEMS sensors offers a detection platform that has the required analytical performance and fabrication capabilities to serve as the foundation for the development of a viable alternative to more costly and less versatile NH3 detection instrumentation. To that end, our Phase I experiments focused on the following: 1) developing of a suite of novel NH3-sensitive molecules; 2) optimizing blend formulations for solution deposition of stable polymer films on MEMs chemicapacitor and chemiresistors; 3) assessing the performance and abstracting rational information regarding the relationship between the molecular structure of the NH3 -sensitive materials and their sensor performance; 4) demonstrating the sensitivity and stability of the detection platform with ppm limits of detection, thermal stability from 20°C - 40°C; 5) developing a rational plan to improve LATP NH3 sensitivity; 6) outlining the steps necessary to optimize performance and develop an advanced prototype for in a phase II where we would seek to further validate this system with field testing in relevant agricultural settings (ie. poultry & cattle farms, etc.).The goal of the proposed Phase II program is to complete optimization of the materials-sensor integration, complete advanced NH3 and temperature testing, and develop and validate gas-phase NH3 detector prototypes with accurate calibration and temperature compensation algorithms. Based on insight gained from the Phase I results, Seacoast will advance the materials-sensor integration by improving upon the molecular design/opportunities presented by the composites for enhanced sensitivity, performance, and stability to the sensor array in SA1. Advanced gas-phase NH3 testing of these detectors will be performed in a specialized environmental chamber designed and built by Seacoast in SA2. Temperature training data will be collected and aging behavior will be studied for detailed calibrations and compensation algorithms. In SA3 Seacoast will investigate optimal methods to integrate the prototypes with electronics, select a path forward in the design and development of these prototypes, and construct 10 prototypes, with associated development of multiplexed readout circuitry and detection algorithms. Finally, in SA4 Seacoast will test the prototypes in a real-world agricultural environment and develop an optimized design and transition plan to scale the resulting "pre-production" prototypes to the final commercial stage. The Specific Aims and tasks are strategically divided between Seacoast, University of Georgia (UGA), and 3rd party contractors to afford maximum efficiency and efficacy in prototype development and validation.Criteria for Success: The Phase 2 project's success will be demonstrated by our ability to: (1) optimize LATP materials for enhanced stability and lifetime (2) demonstrate NH3-resistant electronics, waterproof casing, and user-friendly software interface in with the prototype detectors (3) successfully test prototype by a 3rd party laboratory and perform feasibility studies in real-world environment at commercial farm. To demonstrate sensitivity and ruggedness requirements, and (4) show prototypes log and report NH3 exposure vs. interferents accurately within statistical error.
Project Methods
?The Phase II methods support a technical R&D approach program which will facilitate optimization of the materials-sensor integration, completion of advanced NH3 and temperature testing, and allow for the development and validation of gas-phase NH3 detector prototypes with accurate calibration and temperature compensation algorithms. Based on insight gained from the Phase I results, Seacoast will advance the materials-sensor integration by using materials synthesis to improve upon the molecular design of the target composites for enhanced sensitivity, performance, and stability to the sensor array, and selecting the appropriate chemiresistor and chemicapacitor sensor architecture which maximize sensitivity and lifetime. Advanced gas-phase NH3 testing of these sensors will be performed in a specialized environmental chamber designed and built by Seacoast, which allows fine control over the concentrations and relative ratios of multiple vapors in addition to temperature and humidity. Temperature training data will be collected and aging behavior will be studied for detailed calibrations and compensation algorithms.The chemometric approach of our detection platform relies on statistical analyses of unique MEMS transduction signals to identify and distinguish NH3 concentrations in the presence of interferents likely to be present at agricultural sites. Seacoast will use the collected training data to develop stochastic calibration algorithm models, implemented in software to compensate for environmental variables and to identify and distinguish the principle molecular target, first on a PC, then on the prototypes. Dr. Gray will augment Seacoast's efforts to develop tailored calibration plots and pattern recognition algorithms using results from the vapor tests. Stochastic methods will be utilized to produce calibration plots and algorithms targeting 0.01 ppb LOD for NH3.In 2018, Seacoast developed the SC-214 circuit for developing our chemical sensor products. This circuit allows parallel measurement of the resistance- and capacitance-based detectors and contains a commercial humidity and temperature sensor for calibrations. The SC-214's resistance array is used for rapid testing of new materials (8 simultaneously). The SC-214 also supports simultaneous measurement of a Seacoast's capacitor array for parallel screening of up to 3 materials. The SC-214 has a USB interface for real-time data collection and a logging feature for storing raw data from the sensors with a timestamp, thus allowing data logging when the detector is disconnected from a computer and placed in service. The system operates for ~4hrs on one AAAA battery, which can be expanded for longer operation, measuring several sensors many 6-10 times per minute and updating the display.The SC-214 will serve as a starting point for the Phase II development, with new features added or removed and shielding and packaging developed around this form-factor. The current SC-214 has three programmable LEDs (red, green, blue), which we will assign to act as exposure alarm level indicators, with settings at 2x, 5x, and 20x background. The LEDs can be programmed to blink at various rates, for example, they can blink faster as the next alarm level is approached. Once the user interface is complete, these values will be user-definable to allow the system to be customized for different situations. The microprocessor firmware will measure the raw capacitances and resistances. Then, as calibrations are developed and programmed, the exposure rate, cumulative (time-integrated) dose, time stamp, operational status, and other parameters needed to debug the systems will be logged.Because the proposed NH3 detector is intended to be sufficiently rugged for compatibility with outdoor agricultural sites, it will also need to function efficiently in the presence of PM2.5 dust and other airborne particulates. Protection strategies will be evaluated in Phase II, including use of mesh screens, for filtering out dust, GoreTex membranes and vents for blocking water and filtering particulates. Seacoast will also investigate how to integrate the product with one of the many commercial sensor protection shields used for outdoor mounted sensors.Seacoast will integrate an on-board display and wireless communication for remote display and networking with the test. Each of these are common mass-produced components and cost ~$5 in prototype volumes. We will use a low-power FCC certified Bluetooth™ radio to save battery power and limit unwanted EM transmissions. The SC-214 already accommodates a USB, which will be retained for debugging and real-time data collection for fixed deployments. Onboard memory will meet the needs of the circuit design, data processing algorithms, calibration equations, and data storage sufficient for the entire work shift. We will develop software for monitoring real-time NH3 intensity and duration, with algorithms to calculate cumulative exposure & compensate for interferences, which will be programmed in the system's firmware. Our user interface (Task 3.2) will be adapted to accommodate data (timestamp, intensity, cumulative load, etc.) download from the on-board memory. We will work with potential customers, identified in the TABA assistance, to determine other features that would be appropriate for the end-user. Time and costs are budgeted for a first circuit fabrication run focused on measurement circuits, debugging, and a second optimized circuit run. Optimization will focus on reducing noise and adding data processing.Seacoast will develop a PC-based interface, as we do for all current products, prototypes, and research. For prototype testing, the software will read the sensors in real-time, and include an option for reading stored-data from the circuit. We will develop an identifier to link the unit, present the end-user with a summary report of the data, and store the data and other relevant information in a database for later use. We will develop barcoding to link the user to the sensor. The PC-based interface will be used to optimize detection, calibration and other data-processing algorithms before final implementation in the circuit. After all features have been implemented on the PC, we will port the software to an application compatible with a personal computing device.Ten prototype sensor arrays will be constructed for laboratory testing. We will use built-in LEDs as additional alarms to notify the user of hazardous NH3 doses or dose rates. QC validation tests will be developed in Phase II to qualify the systems. Once circuit layout is done, we can design and build a suitable detector housing. The entire system will be sealed in a plastic enclosure to protect it from water, and chemical interferents (SA2.1). Ports will be provided for the battery. The sensors and circuits are all low-voltage/low-current components; thus, the designs will meet intrinsic safety requirements. The primary concern will be protecting the battery and electronics from liquids and chemicals; thus, a water-tight enclosure will be designed and assembled. Our CNC mill will be used for prototyping.Assembled prototypes will be sent to Dr. Lilong Chai (UGA), Dr. Tim Griffis, and Haddock's Poultry Green Farm for testing under simulated field conditions and general product review. We will develop a user manual, test plan, and set of validation tests based on the detection goals of the project (sensitivity standards, 10 ppb to 5000 ppm). Prototypes will be tested via exposure to gas-phase NH3 from various sources. Test results will be used to improve the system in an iterative process, before moving on to the next stage of testing. Modifications will lead to an updated prototype that will undergo "simulated field testing" in the enclosure. Results will feed the design of the 3rd gen. prototype for final commercialization.

Progress 09/01/22 to 02/28/25

Outputs
Target Audience:Our target audience broadly falls into two categories: 1) those who are interested in on-site monitoring of ammonia in animal shelters (i.e., farmers, agricultural enterprises), and 2) those who are interested in general monitoring of air pollution (i.e., private, public, government, and non-profits focused on environmental protection and sustainability). Changes/Problems:Changes that occurred to the program personnel: Dr. John Cowart, initially tasked as the Project Director/ Principal Investigator, has left Seacoast Science and was replaced by Dr. William K. Tolley. Peter Gray, NJB Companies, will no longer be working on the project; his data processing tasks were assumed by Dr. Sanjay Patel at Seacoast Science. As a result of personnel changes, Seacoast requested and was granted a no-cost extension. What opportunities for training and professional development has the project provided?Students supported through this work: - Seacoast sponsored a summer intern (a chemical engineering student from UC Berkeley) training in the use of HPLC/GPC to analyze the synthesis products for purity. The GPC instrument also allows for capture of individual fractions of an analytical sample; thus, the GPC can separate individual compounds produced during polymer synthesis. This intern fractionated the LATP materials developed in this project for subsequent coatings as capacitive polymers-based sensors. This intern went on to graduate work in chemical engineering. The separation methods utilized by this student were effective in isolating products that proved to be highly effective for detection purposes, even though these products were not used in the field test units. This project also supported in part the work of three students at UGA as detailed in the report from Prof. Chai How have the results been disseminated to communities of interest?Seacoast delivered 10 detectors to Prof. Lilong Chai at the Poultry Science facility in Athens, GA, at the University of Georgia. Dr. Chai is a potential customer and end-user of the proposed technology for his own research and through his collaborations will be able to support demonstrations of the sensors to chicken farmers and others in the industry. Dr. Chai has approached chicken farms in the region near UGA and discussed our application. His report of the work, including publications What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Seacoast fabricated robust, cost-efficient ammonia detectors using these detector materials. These detectors were installed and operated in enclosures at the poultry research facility at the University of Georgia. The particular enclosure housed approximately 40 domesticated hens. Detectors downloaded data wirelessly to a central computer setup. Detectors operated continuously for the period Sept. 11, 2024 to Feb. 11, 2025. Testing of the detectors following this field test period showed no degradation of ammonia detection over the course of 5 months (Fig. 2). Seacoast tested capacitance sensors coated with LATP against ammonia and other vapors to collect data that could be used to develop temperature and humidity compensating algorithms. Unfortunately, interferences from temperature and humidity have proven too complex to this point to allow an accurate algorithm to report ammonia concentrations.

Publications

  • Type: Peer Reviewed Journal Articles Status: Published Year Published: 2023 Citation: Bist, R. B., Subedi, S., Chai, L., & Yang, X. (2023). Ammonia emissions, impacts, and mitigation strategies for poultry production: A critical review. Journal of Environmental Management, 328, 116919.


Progress 09/01/23 to 08/31/24

Outputs
Target Audience:During this reporting period, our primary target audience has been the researchers and students at the University of Georgia, particularly those involved in Poultry Science and practical applications of sensor technology systems in live environments. This audience is essential as they provide critical feedback on the functionality and usability of our sensor system, which is currently in the development stage. We specifically focused on this group for several reasons: Expertise and Feedback: The University of Georgia is renowned for its research in agricultural sciences. Engaging with its faculty and students allows us to gather informed perspectives on the user experience and technical aspects of our sensor system. Their feedback is invaluable as we strive to optimize our technology for practical application in everyday agricultural settings. Collaborative Opportunities: By working closely with the university, we can explore potential partnerships that may lead to collaborative research opportunities. This enhances the depth of our project and fosters knowledge exchange between our team and academia. Preparation for Testing: As we prepare for upcoming in-lab testing, understanding how our sensor system can be integrated and utilized in real-world farming scenarios is crucial. Engaging the University of Georgia helps ensure that our design is aligned with best practices and the needs of end-users. Diversity in Engagement: We also aim to include a diverse range of voices and perspectives within our target audience, including those from underrepresented racial and ethnic backgrounds in science and technology. This effort ensures that our research is inclusive and can address the needs of all communities involved in agriculture. In conclusion, our targeted interactions with the University of Georgia during this reporting period have been foundational to our project, allowing us to gather critical user insights that will drive the successful development of our sensor technology. This audience is key to understanding "to whom our work/research matters and why," as their involvement will ultimately facilitate the transition from development to practical application in the agricultural sector. Changes/Problems:Challenges and Timeline Impact Changes that occurred to the program personnel: Dr. John Cowart, initially tasked as the Project Director/ Principal Investigator, has left Seacoast Science and was replaced by Dr. William K. Tolley. Peter Gray, NJB Companies, will no longer be working on the project; his data processing tasks were assumed by Dr. Sanjay Patel at Seacoast Science. Throughout this project, Seacoast faced challenges related to the subpar performance of the initial LATP materials, difficulties in data communication for the sensor prototypes, and the need for further optimization in the integration of hardware components. These issues have impacted our timeline significantly, necessitating a request for a no-cost extension to ensure we meet our project objectives effectively. We have established a new end date for the project in February 2025. What opportunities for training and professional development has the project provided?Students supported through this work: - Seacoast sponsored a summer intern (a chemical engineering student from UC Berkeley) training in the use of HPLC/GPC to analyze the synthesis products for purity. The GPC instrument also allows for capture of individual fractions of an analytical sample; thus, the GPC can separate individual compounds produced during polymer synthesis. The intern has used the instrument to fractionate the LATP materials developed in this project for subsequent coatings as capacitive polymers-based sensors. This intern went on to graduate work in chemical engineering. The separation methods utilized by this student were effective in isolating products that proved to be highly effective for detection purposes, even though these products were not used in the field test units. This project also supported in part the work of three students at UGA How have the results been disseminated to communities of interest?Thus far, dissemination of the project progress has been limited to video conferencing with Dr. Chai (UGA) to discuss the status of our work and the plans we have for testing the sensors at the UGA designated test sites. Dr. Chai is a potential customer and end-user of the proposed technology for his own research and through his collaborations will be able to support demonstrations of the sensors to chicken farmers and others in the industry. Dr. Chai has approached chicken farms in the region near UGA and discussed our application. What do you plan to do during the next reporting period to accomplish the goals?This is the final report and Seacoast / UGA achieved the objective of fabricating portable detectors for ammonia; thus, no further work is anticipated. The resultant detectors have been field tested at the Poultry Research Facility at UGA.

Impacts
What was accomplished under these goals? Overview: In the second year of this Phase II project, Seacoast synthesized Lewis-Acid Telechelic Polymers (LATP) derivatives searching for improvements in ammonia detection. In addition, Seacoast tested other chemical sensing polymers that could provide greater sensitivity and/or selectivity in the detection of ammonia, followed by characterization of the responses of these materials when coated onto Seacoast's transducer platforms. Further, Seacoast upgraded performance of the measurement circuitry used in Phase I to more accurately assess detector responses. In preparation for Phase II / Year 2 field tests, Seacoast designed and fabricated rugged enclosures for the ammonia detector to minimize potential negative effects of moisture and dust on sensor performance. Specific Aim 1: Optimize Materials-Sensor Integration In Phase II, Seacoast repeated synthesis of tetramethyl 2,2' - (((ethane-1,2-diylbis (1,1,3,3 - tetramethyldisiloxane-3,1-diyl)) bis(ethane-2,1 -diyl)) bis (4,1-phenylene)) (4R,4'R,5R,5'R) -bis (1,3,2-dioxaborolane-4,5-dicarboxylate) - designated "173D" as the most effective of the polymers synthesized in Phase I for detecting ammonia vapor. Based on tests in our vapor test systems, the limit of detection (LOD) for ammonia in these tests was found as 1 ppm. To further elucidate the effectiveness of the LATP synthesis procedure and further the effort toward better sensor responses, Seacoast examined composition of the polymer using gel permeation chromatography (GPC). The basic mechanism of this instrument is to separate compounds based on molecular size - smaller molecules penetrate the porous packing beads to a greater depth and are thus delayed in elution. The chromatography data showed a large peak, believed to be the desired active LATP; some heavy impurity materials elute early in the chromatogram and a small amount of beginning boronic ester elutes as the final observed peak. Recognizing that the ultimate objective in this project is the development of a robust detector for ammonia vapors in buildings housing poultry, Seacoast also considered earlier work to detect highly polar compounds using siloxane-based sol-gel coatings on capacitance transducers. Tests were conducted at both 25 and 35°C. LATP capacitor responses at 30 ppm ammonia at 25°C are approximately 2% capacitance change; sol-gel sensor response is approximately 5% under the same conditions. Based on these results, Seacoast considers sol-gel sensors as interesting as polymers for ammonia detection but time constraints limited pursuit of these materials for ammonia detection. Work with GPC led Seacoast to test purified fractions from polymers already in use for other sensor applications. One particularly interesting polymer fraction is a fraction from a carbosilane polymer designated by Seacoast as "3STH134." Specific Aim 2: Sensor Testing & Compensation Algorithms Seacoast tested capacitance sensors coated with LATP against ammonia and other vapors to collect data that could be used to develop temperature and humidity compensating algorithms. These and similar data are to be used in developing the algorithm that will calculate ammonia concentrations in the air with appropriate compensations for temperature and humidity. Specific Aim 3: Integrate Sensors and Validate Prototypes The third Aim of Phase II is to complete the integration of ammonia detector prototypes and test them in a realistic environment. This work involved redesigning the readout circuit for modularity with connectors for adding a circulation fan, additional 3rd-party sensors, or circuits for wireless communications. A detector enclosure was designed and prototyped that includes a particulate filter to prevent intrusion of airborne dust and aerosols that may be present in animal shelters. Leveraging work in another SBIR program, we redesigned the capacitive microchips to allow independent drive lines with three standard sized capacitors. Seacoast determined that the original SC214 circuitry could be modified, adding operational amplifiers to improve its measurement accuracy and to decouple the capacitance measurement circuits to allow independent measurements of each of the three capacitance sensor elements. Firmware modifications, in addition to accommodating the new hardware, included improvements in the measurement timing and discharging of the capacitors to ensure accurate measurements of any offsets generated by the new circuit. Oversampling (averaging) was increased, and the auto-ranging protocol was improved to mitigate mismatches at transitions between sensitivity ranges, and to reduce noise. This new circuit, designated the SC-220, has mounting holes for placement of the circuit board in the enclosure and has added connectors for powering fans or pumps. The battery holder was replaced with a connector to allow the power supply to be adapted to future applications. The detectors contained LED lights to diagnose operation of the detectors. The blue light indicates proper operation of the device. The green light indicates proper communication with the wireless master receiver. Ultimately, 10 working detectors were fabricated for field testing at the University of Georgia Poultry Research Facility with work overseen by Dr. Lilong Chai; detectors were delivered and installed on Sept. 11, 2024. The test facility consisted of a cinder block enclosure (~7 m square) containing four pens ~2 m square each. Two pens housed ~40 hens (45 weeks old at the time of detector installation. Installation of the 10 units was accomplished within 2 hours and the detectors operated for 4 weeks without interruption or issue. Specific Aim 4: Optimize Designs for Production In the effort to design a detector suitable for mass production, Seacoast opted to switch the sensor polymer from a custom-synthesized LATP to a commercially available polymer Gantrez AN-119. Details of the fabrication are detailed in the Bill of Materials in the Appendices. 4) Issues: The principal investigator John Cowart is no longer with Seacoast Science, Inc.; PI responsibilities were undertaken by Dr. William Tolley. Algorithm development has been reassigned to Dr. Sanjay Patel, CTO at Seacoast Science, Inc. Because of this, work was delayed and Seacoast requested and received authorization for a no-cost extension.

Publications


    Progress 09/01/22 to 08/31/23

    Outputs
    Target Audience:Our objective in this research is to develop a robust, cost-efficient ammonia detector to quantify ammonia concentrations in air. Our target audience broadly falls into two categories: 1) those who are interested in on-site monitoring of ammonia in animal shelters (i.e., farmers, agricultural enterprises), and 2) those who are interested in general monitoring of air pollution (i.e., private, public, government, and non-profits focused on environmental protection and sustainability). COTS ammonia sensors have proven too unreliable for long-term, real-time monitoring of air in shelters housing farm animals, where ammonia emanates from animal wastes and may negatively impact animal health. Our Phase I customer discovery yielded insightful interviews with field-experts in the agriculture and environmental protection industries. The interviewees elucidated the performance specifications desired both by users at a site and users monitoring from a remote location needing to monitor hazardous chemicals in air. For detectors that will be used on-site by farmers, important detector characteristics are affordability, accuracy, ruggedness, ease-of-use, and low maintenance. Farmers desire a turnkey solution, with easy setup, that can last at least 1 year in enclosed poultry houses exposed to associated temperature, humidity, wind, and dust conditions. Market research revealed a need for accurate hourly ammonia measurements irrespective of meteorological and environmental variables (i.e., humidity, temp.) to better promote animal growth and health. As a secondary objective, users desire data that can be shared with the scientific community to facilitate the development of predictive models for environmental phenomena. Changes/Problems:Two changes have occurred to the program personnel. Dr. John Cowart, initially tasked as the Project Director/ Principal Investigator, has left Seacoast Science. The project lead has been taken over by Dr. William K. Tolley. Peter Gray, NJB Companies, will no longer be working on the project; his data processing tasks will be taken over by Dr. Sanjay Patel at Seacoast Science. What opportunities for training and professional development has the project provided?Summer intern at Seacoast Science - Seacoast has a summer intern (a chemical engineering student from UC Berkeley) training in the use of HPLC/GPC to analyze the synthesis products for purity. The GPC instrument also allows for capture of individual fractions of an analytical sample; thus, the GPC can separate individual compounds produced during polymer synthesis. The intern has used the instrument to fractionate the LATP materials developed in this project for subsequent coatings as capacitive polymers-based sensors How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals?In the second year of the program, Seacoast intends assembly of prototypes for field testing at the University of Georgia test sites. We have had discussions with Professor Chai to plan for testing in buildings housing live poultry. We also intend to pursue the use of sol-gel coatings in parallel with LATP-coated sensors.

    Impacts
    What was accomplished under these goals? Overview: In the first year of this Phase II project, Seacoast focused on synthesizing repeat batches of the novel Lewis-Acid Telechelic Polymers (LATP) demonstrated in Phase 1, followed by characterization of the responses of these materials when coated onto Seacoast's transducer platforms. Seacoast also has modified the design of the measurement circuitry used in Phase I to assess detector responses more accurately. In preparation for Phase II / Year 2 field tests, Seacoast has designed a rugged enclosure for the ammonia detector to minimize potential negative effects of moisture and dust on sensor performance. These prototype development tasks were performed in parallel. Specific Aim 1. Optimize materials-sensor integration for enhanced sensitivity/stability. In Phase II, Seacoast repeated synthesis of tetramethyl 2,2' - (((ethane-1,2-diylbis (1,1,3,3 - tetramethyldisiloxane-3,1-diyl)) bis(ethane-2,1 -diyl)) bis (4,1-phenylene)) (4R,4'R,5R,5'R) -bis (1,3,2-dioxaborolane-4,5-dicarboxylate) - designated "173D" as the most effective of the polymers synthesized in Phase I for detecting ammonia vapor. Based on tests in our vapor test systems, the limit of detection (LOD) for ammonia in these tests is calculated as 1 ppm. Carbon dioxide, exhaled during respiration, is a potential interferent and can accumulate in poorly ventilated, occupied spaces, potentially interfering with ammonia measurements. The above material produced a measurable response to CO2 at concentrations up to 10,000 ppm. Additional interferent tests will be conducted in the next reporting period. To further elucidate the effectiveness of the LATP synthesis procedure and further the effort toward better sensor responses, Seacoast examined composition of the polymer using gel permeation chromatography (GPC). The basic mechanism of this instrument is to separate compounds based on molecular size - smaller molecules penetrate the porous packing beads to a greater depth and are thus delayed in elution. The chromatography data showed a large peak, attributed to the desired active LATP; some heavy impurity materials elute early in the chromatogram and a small amount of beginning boronic ester elutes as the final observed peak. Recognizing that the ultimate objective in this project is the development of a robust detector for ammonia vapors in buildings housing poultry, Seacoast also has considered related work done earlier to detect highly polar compounds such as ammonia using siloxane-based sol-gel coatings on capacitance transducers. Tests were conducted at both 25 and 35°C. The best of the LATP capacitor responses at 30 ppm ammonia at 25°C are approximately 8% capacitance change; sol-gel sensor response is approximately 5% under the same conditions. Based on these results, Seacoast considers sol-gel sensors as interesting as polymers for ammonia detecting. To date, tests do not address robustness or lifetime durability. However, these data provide direction for future work wherein we will test sol-gel sensors in parallel with LATP-based sensors. Specific Aim 2. Conduct sensor testing & develop compensation algorithms. Seacoast tested capacitance sensors coated with LATP against ammonia and other vapors to collect data that could be used to develop temperature and humidity compensating algorithms. These and similar data are to be used in developing the algorithm that will calculate ammonia concentrations in the air with appropriate compensations for temperature and humidity. Specific Aim 3. Integrate the sensors and readout systems; validate prototypes. The third Aim of Phase II is to complete the integration of ammonia detector prototypes and test them in a realistic environment. This work is ongoing and scheduled for completion by the end of the 6th project quarter. To date, Seacoast has redesigned the readout circuit, and expects to have new circuits fabricated in Late Q4 or early Q5. The circuit is designed for modularity with connectors for adding a circulation fan, additional 3rd-party sensors, or circuits for wireless communications. A new enclosure has been designed and prototyped that includes a particulate filter to prevent intrusion of airborne dust and aerosols that may be present in animal shelters. Leveraging work in another SBIR program, we redesigned the capacitive microchips to allow independent drive lines with three standard sized capacitors. Seacoast determined that the original SC214 circuitry could be modified, adding operational amplifiers to improve its measurement accuracy and to decouple the capacitance measurement circuits to allow independent measurements of each of the three capacitance sensor elements. Firmware modifications, in addition to accommodating the new hardware, included improvements in the measurement timing and discharging of the capacitors to ensure accurate measurements of any offsets generated by the new circuit. Oversampling (averaging) was increased, and the auto-ranging protocol was improved to mitigate mismatches at transitions between sensitivity ranges, and to reduce noise. This new circuit, designated the SC-220, has mounting holes for placement of the circuit board in the enclosure and has added connectors for powering fans or pumps. The battery holder was replaced with a connector to allow the power supply to be adapted to future applications. Specific Aim 4. Optimize designs for production. Nothing to report at this time. 4) Issues: The principal investigator John Cowart is no longer with Seacoast Science, Inc.; PI responsibilities were undertaken by Dr. William Tolley. Algorithm development has been reassigned to Dr. Sanjay Patel, CTO at Seacoast Science, Inc

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