ORCID Identifier(s)


Graduation Semester and Year




Document Type


Degree Name

Master of Science in Mechanical Engineering


Mechanical and Aerospace Engineering

First Advisor

Jung-Chih Chiao


The purpose of this study is to demonstrate a novel method of using a flexible MEMS-based pH sensor for agricultural and biomedical applications. The first part of the thesis involves demonstration of the capability of our pH sensor for monitoring pH level change in the food product. The pH sensor we have developed consists of Iridium Oxide (IrOx) and Silver Chloride (AgCl) sensing electrodes. The sensor is designed to monitor and sustain long-term continuous usage, which makes it suitable for a wide variety of agricultural based applications. The electrochemical potential generated between IrOx and AgCl electrode is monitored and further correlated with corresponding pH values. In this embodiment, pH sensors are tested for in-situ continuous monitoring of spoilage pattern of fish for 40-48 hrs. The feasibility of monitoring pH values in fish meat that could further represent and identify spoilage has been demonstrated. In the second half of the thesis, application of the flexible IrOx/AgCl pH sensor combined with a Copper (Cu) based impedance sensor is demonstrated for a biomedical application. In this study, the pH sensor and impedance sensors are used to monitor pulmonary aspiration during procedural sedation. Nowadays, for various surgical procedures, Laryngeal mask airways (LMA) are used as an effective method of ventilation. During a surgical procedure, if the patient has not fasted properly then the patient is at a high chance of pulmonary aspiration. In such a situation, gastric fluid will start flushing into the larynx and lower respiratory tract, which could have a detrimental effect on patient health. To demonstrate the use of our sensors to track gastric fluid, in-vitro experiments were conducted by embedding the sensors on LMA. Potassium Chloride (KCl) solution is flushed through the system creating reflux episodes and corresponding readings were recorded.


pH, Impedance sensor, Agriculture, Biomedical, MEMS


Aerospace Engineering | Engineering | Mechanical Engineering


Degree granted by The University of Texas at Arlington