Mach-Zehnder interferometer fiber optic sensor coated with UiO-66 metal organic framework for creatinine detection

An in-line Mach-Zehnder fiber optic sensor based is proposed and fabricated to measure creatinine (CR) concentration in the physiological range for clinical trials. The shift in valleys wavelength is monitored to assess the sensor response to the variation of CR concentration. Single-mode fiber as the sensing part is coated with UiO-66 metal-organic framework (MOF) adsorbent by dip coating to enhance the performance of the sensor. For further improvement, the length of the SMF and the coating time of the UiO-66 are optimized. The sensitivity and limit of detection (LOD) of the optimized bare sensor are 1530 pm/(mg/dL) and 0.4 mg/dL, respectively. The sensor with optimized UiO-66 coating thickness has a sensitivity of 2400 pm/(mg/dL) and an LOD of 0.2 mg/dL indicating the high performance. The sensors offer fast response, high sensitivity, and proper linear response at low concentrations of CR which reveal their potential in bio and chemical applications.