Date of Award

May 2020

Document Type


Degree Name

Master of Science (MS)



Committee Member

Carlos D Garcia

Committee Member

W. B Pennington

Committee Member

R. K Marcus


Ammonia is a naturally-occurring gas, present throughout the atmosphere at sub-ppb concentrations. As result of various processes, significantly higher concentrations can be found in the areas surrounding industrial and agricultural operations. In such cases, the presence of NH3 in air not only is associated with a very pungent odor and potential toxicity but can also affect the environment, animals, plants, and humans. Aiming to provide a simple platform to monitor NH3 in air, a paper-derived gas sensor, integrating a natural deep eutectic solvent (NADES) was developed. The herein described paper-derived ammonia gas sensor was fabricated using direct laser scribing, to form a carbon-based interdigitated array. Characterization and optimization (using chemometrics) were performed to develop a material with the lowest possible resistivity. A unique feature of the proposed sensor is that it integrates a natural deep eutectic solvent formed with lactic acid:glucose:water (LGH). This NADES conveys selectivity toward ammonia (over methanol, ethanol, 1-propanol, and water) and greatly enhances the sensitivity of the sensor (over the plain carbon array). The resistivity of the sensor was dependent on the NH3 concentration in the 0.11 – 40.6 % range and has an estimated limit of detection of 0.11 %. Although the sensitivity of the sensor is lower than that of others based on metallic oxides, this approach represents a low-cost, portable, and simple way to detect and measure ammonia in gas phase.



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