Ammonia sensor for point-of-care application.

• Main Author: Png, Shermaine.
• Other Authors: Chan Chi Chiu
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Bioengineering
• Online Access: http://hdl.handle.net/10356/52854
• Institution: Nanyang Technological University

Blood ammonia level when persistent at levels beyond the acceptable range of 40μM, can have detrimental effects to the human body such as liver dysfunction as well as damage of the central nervous system. Over the years, many techniques have been discovered to quantify ammonia in the body with the enzymatic method being the most popular technique of all. However, measurement of ammonia via this technique requires sophisticated laboratory instruments and skilled labour especially during the handling of blood samples. Hence, a point-of-care optical biosensor was proposed to allow fast, immediate and easy measurement of ammonia in blood. The point-of-care optical biosensor utilizes the Mach-Zehnder type interferometer, along with a responsive hydrogel – acrylamide. The sensing mechanism used for this point-of-care biosensor is known as the Berthelot reaction, which involve chemical reactions between ammonia, hypochlorite and two phenol groups. Different acrylamide compositions were investigated by varying the acrylamide monomer and glycidyl methacrylate (GMA) concentration. In this report, 18wt/v% and 22wt/v% monomer as well as 1.875mol% and 7mol% GMA were studied. Results revealed that sensors coated with acrylamide gel, having a combination of 18wt/v% monomer and 1.875mol% GMA had better response and sensitivity. Data collected corresponds well with literature and the biosensor can be used for early detection of elevated blood ammonia levels.