Laser biosensor as for pregnancy test by using photonic crystal fiber

The use of laser and optoelectronics concepts to develop biological detection systems is the goal of this work. A biosensor based on one of the interferometer techniques, Mach-Zhender interferometer (MZI) technique, and the using of the laser beam is developed for pregnancy detection or pregnancy hormone, Human chorionic gonadotropin (HCG), increasing. A part of photonic crystal fiber (PCF) with 3 different lengths (1.5 cm, 1.0 cm, and 0.5 cm) has been collapsed with 2 conventional single mode fibers (SMFs) to achieve MZI technique, Micro-holes collapsing-and make high sensitive regions for the optical properties (refractive index and absorption) in the urine sample. This-type of laser biosensor depends on light intensity measurement through a modified optical fiber. The sensing region-is immersed in different urine samples of pregnant female and non-pregnant female. Biological changes in the urine sample due to the HCG increasing lead to a change in the optical properties (refractive index and absorption) of the urine sample. The results showed that the increasing of pregnancy hormones leads to an increase in the refractive-index for a urine sample and a decrease in the intensity of the output laser beam. From this test, the calibration curve-of laser biosensor for a pregnancy test or pregnancy detection has been found. The sensitivities of the laser biosensor-with a refractive index in the range (1.33864-1.34257) at (1.5 cm, 1.0 cm, and 0.5 cm) PCF length are 61.142 ABS/ RIU, 4.5132 ABS/RIU and 2.888 ABS/RIU, respectively. Thus, the highest sensitivity was found for the (1.5 cm) photonic crystal fiber length.