Fiber bundled probe for highly sensitive sensor for zinc ion detection using a concave mirror

We experimentally demonstrate a bundled optical fiber based sensor for measuring zinc ion concentration. When zinc ions in liquid samples are shined with red laser light operating at about 630 nm wavelength it is observed that the intensity of the reflected radiation from the concave mirror, which was collected by the receiving fiber increases linearly with the increment of zinc ions concentration in the liquid sample. Our sensor has a simple architecture, it exhibits good sensitivity, linearity, and stability as it was tested with zinc ions concentration within 0% to 2%. It shows the highest sensitivity of 470 mV/% with the linearity of 92% and resolution of 0.0015%. The proposed sensor is based on optical non-destructive and on-site measurement, which may has applications in medical field.