Acta Phys. -Chim. Sin. ›› 2017, Vol. 33 ›› Issue (12): 2523-2531.doi: 10.3866/PKU.WHXB201706091

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Detection Sensitivity to Benzo[a]pyrene of Nanoporous TiO2 Thin-Film Waveguide Resonance Sensor

Xiu-Mei WAN1,2,Li WANG1,2,Xiao-Qing GONG1,2,Dan-Feng LU1,Zhi-Mei QI1,*()   

  1. 1 State Key Laboratory of Transducer Technology, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, P. R. China
    2 University of Chinese Academy of Sciences, Beijing 100049, P. R. China
  • Received:2017-05-18 Published:2017-09-05
  • Contact: Zhi-Mei QI
  • Supported by:
    the National Key Basic Research Program of China (973)(2015CB352100);National Natural Science Foundation of China(61377064);National Natural Science Foundation of China(61675203);Research Equipment Development Project of Chinese Academy of Sciences(YZ201508)


Nanoporous TiO2 (NPT) films with a thickness of about 295 nm were prepared through the sol-gel copolymer-templating approach on a 40-nm-thick gold film sputtered on a glass substrate for optical waveguide resonance (OWR) sensing. Using the prism-coupled Kretschmann configuration, a single resonance dip was observed in the wavelength range from visible to near infrared, which was attributed to the second order transverse magnetic mode of the OWR chip based on the phase-match condition. By using a combination of Fresnel theory and Bruggeman equation to fit the measured resonance dip, the porosity of NPT films was determined to be about 0.4. After hydrophobilization of the NPT films, the OWR chips were used for both in-situ and ex-situ detections of benzo[a]pyrene (BaP) in water. The experimental results indicate that the ex-situ detection sensitivity to BaP is 2 times higher than the in-situ detection sensitivity. The lowest concentration of BaP detectable with the hydrophobilized OWR chip is ca. 100 nmol·L-1. The experimental comparisons reveal that both the nanoporous structure and hydrophobilization of the OWR chip enable to enhance the sensor's sensitivity to BaP. The work demonstrated that the NPT thin-film OWR sensing chips are stable and robust with good reusability.

Key words: Benzo (a) pyrene, Optical waveguide resonance sensor, Nanoporous TiO2 thin films, Hydrophobilization, Sensitivity enhancement


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