Cholesterol detection using optical fiber sensor based on intensity modulation

The aim of the research is to detect the concentration of cholesterol by using the principle that a laser beam propagation is guided by optical fiber bundle in term of intensity profile through solution with vary concentrations of cholesterol from 0 to 300 ppm. The mechanism of cholesterol concentration detection is the propagation of He-Ne laser beam with wavelength of 632.5 nm through a fiber optic bundle and a solution of cholesterol, then is reflected by a flat mirror and enters receiving fiber. This signal is captured by a silicon detector (SL-818, Newport) in the form of output voltage. The result showed that the output voltage decrease linearly with the increase of concentration of cholesterol with a sensitivity of 0.0004 mV/ppm and the linearity more than 97%.