DUMBBELL SHAPED INLINE MACH–ZEHNDER INTERFEROMETER FOR BIO-CHEMICAL DETECTION

A new dumbbell-shaped inline Mach Zehnder interferometer (MZI) is developed using an arcing process of a fusion splicer for measurement of various bio-chemical concentrations in distilled water. The sensor probe consists of two bulges separated by a tapered waist that generates a good reflected interference spectrum. The interference spectrum is red-shifted with the increase in the bio-chemical concentration due to the increment of the refractive index of the surrounding medium, which reduces the phase difference between the core and cladding modes. In sensing the concentration of glucose solution from 0% to 12%, the dip wavelength increases from 1554.419 to 1554.939 nm in a quadratic manner with the coefficient of determination of 0.9818. The sensor has a sensitivity of 0.0354nm/%. The corresponding linearity is 99.05% and the limit of detection is 3.87%. For NaCl solution, the shift in dip-wavelength is linearly proportional to the increase in its concentration. The sensitivity obtained is 0.0329 nm/% with a linearity of more than 99.68%. The limit of detection is 4.32%. Lastly, for uric acid solution, the sensitivity obtained is 0.0006 nm/%. The slope shows a good linearity of more than 99.48% for a 7.52% limit of detection.