Gold-coated Fabry-Pérot based optical fiber sensor for monitoring hypoxic state of the tumor from the change of refractive index in red blood cells

A gold-coated Fabry-Pérot base optical fiber sensor is proposed to measure the oxygen level in hypoxic tumors of prostate cancer through measuring the change of refractive index in red blood cells. The sensors are made entirely of glass with a diameter of 220 μm and few mm long. The tip of the sensors is coated with 100 nm thick gold layer to enhance the interaction between the sensor and hemoglobin in red blood cells. In this paper, pig blood solutions with refractive index values between 1.343 and 1.348 depending on hemoglobin concentration are prepared and analyzed. The phase variation of the output signal which is an interference pattern of the reflected spectrum is measured by taking a Fast Fourier Transform of the reflected signal. A sensitivity of 9.44 rad/RIU can be achieved with a resolution 1.27∗10
⁻³
RIU for this sensor.