Double-pass Mach-Zehnder fiber interferometer pH sensor.
A biocompatible fiber-optic pH sensor based on a unique double-pass Mach-Zehnder interferometer is proposed. pH responsive poly(2-hydroxyethyl methacrylate-co-2-(dimethylamino)ethyl methacrylate) hydrogel coating on the fiber swells/deswells in response to local pH, leading to refractive index changes that manifest as shifting of interference dips in the optical spectrum. The pH sensor is tested in spiked phosphate buffer saline and demonstrates high sensitivity of 1.71  nm/pH, pH 0.004 limit of detection with good responsiveness, repeatability, and stability. The proposed sensor has been successfully applied in monitoring the media pH in cell culture experiments to investigate the relationship between pH and cancer cell growth.
Nanyang Technological University, School of Chemical and Biomedical Engineering, Division of Bioengineering, 70 Nanyang Drive, Singapore 637457, Singapore.
Zhi Qiang
ZQ
Tou
Nanyang Technological University, School of Chemical and Biomedical Engineering, Division of Bioengineering, 70 Nanyang Drive, Singapore 637457, Singapore.
Chi Chiu
CC
Chan
Nanyang Technological University, School of Chemical and Biomedical Engineering, Division of Bioengineering, 70 Nanyang Drive, Singapore 637457, Singapore.
Jesmond
J
Hong
Nanyang Technological University, School of Chemical and Biomedical Engineering, Division of Bioengineering, 70 Nanyang Drive, Singapore 637457, Singapore.
Shermaine
S
Png
EINST Technology Pte Ltd, 1092 Lower Delta Road #04-01, Singapore 169203, Singapore.
Khay Ming Tan
KM
Eddie
Nanyang Technological University, School of Chemical and Biomedical Engineering, Division of Bioengineering, 70 Nanyang Drive, Singapore 637457, Singapore.
Terence Aik Huang
TA
Tan
D045744:Cell Line, Tumor; D004867:Equipment Design; D005110:Extracellular Space / Q000737:chemistry; D005336:Fiber Optic Technology / Q000295:instrumentation*; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007368:Interferometry / Q000295:instrumentation* / Q000379:methods; D057230:Limit of Detection; D016014:Linear Models
D020136:Hydrogel, Polyethylene Glycol Dimethacrylate