High sensitivity and ultra-compact optical biosensor for detection of UREA concentration

In this paper, we suggest two-dimensional photonic crystal based biosensors for measurement of urea concentration in urine by means of refractive index detecting. In case of variation of urea concentration in urine, both the output peak intensity and the resonant peak center wavelength will shift. Two different structure dimensions are used to analyze the sensing characteristics of urine. The first sensor consists of a novel square ring joined to a simple waveguide with rods in air configuration. The second sensor is schemed by use of two-dimensional photonic crystals based on air hole in slab with elliptical resonant cavity in the middle of a photonic crystal waveguide. To realize sensing in both cases, we fill air area by urine sample. A high sensitivity is observed in small structures. In addition, we demonstrated a high quality factor, which is superior to those reported in recently published work discussing urine components based on photonic crystal, with small size sensors and fast response times.