6.2 Micro-ring based chemical / biological sensors

Micro-rings except all optical signal processing have been used as building blocks in sensitive bio/chemical sensors either to enhance the sensitivity of MZI based sensors, or as main sensing elements. In the case of MZI sensors one or more resonant cavities are used to increase the power difference between the reference and the sensing branch, due to the high Q factor of the MRs. When the main sensing element is the MR, the sensing is achieved by two distinct ways. A water solution is used as upper coating for the MR and if a chemical or biological agent is inserted into the solution the refractive index of the coating is altered and as a consequence the spectral response of the MR cavity also alters (evanescent sensing). In other cases there are used special chemical agents that act as chemical receptors, they are spread over the ring surface (biotin). In the presence of a solution with anti biotins the two chemical substances interact and bind chemically. The presence of anti biotins alters the effective index of the micro cavity. Due to the high finesse that MR exhibit, a small variation in the refractive index of the material is directly translated to a significant frequency shift, or to a power difference, which can be quantified so as to measure the concentration of the bio/chemical agent. In both cases the MR's surface has to be specially treated, and cleaned for reuse. Both techniques exhibit high sensitivity, and small size. One of our future activities involves the design and characterization of a high performance, low-cost and small size bio sensor, based on MR.


Significant publications:

  • C. Mesaritakis, A. Argyris, E. Grivas, A. Kapsalis and D. Syvridis, "Adaptive Interrogation for Fast Optical Sensing Based on Cascaded Micro-Ring Resonators", IEEE Journal of Sensors, vol. 11 (7), pp. 1595-1601, July 2011.
  • C. Mesaritakis, H. Simos, A. Kapsalis and D. Syvridis, "Optical microring based interrogation method for phase detecting elements", IEEE Journal of Sensors vol. 9, pp. 2016-2023, 2009.
  • C. Mesaritakis, H. Simos, A. Kapsalis, D. Syvridis " Micro Ring Biochemical Sensor Based on Fano Resonances and Nanoslot Waveguides", EOS annual meeting, TOM1 Biophotonics, Paris France, September 2008.