| With the continuous development of optical fiber communication system,high demands are put forward for the low-cost and large scale integration of the light device.So integrated optics arises at the historic moment,and together with the continuous development of existing silicon-based electronics integration technology,formed the silicon-based optoelectronics.And its main goal,was using the existing CMOS technology to fabricate integrated all-optical device.Micro ring resonator as one of the important components of integrated optoelectronic technology,is widely used in all-optical cache,all-optical filters,all-optical switching,all-optical code conversion,wavelength conversion,logic gate and other all-optical signal processing.Due to the low-cost,highly-sensitive,compatible with CMOS process and ultra-compact features of the micro ring resonator,its application in the biomedical field had very big development space,and optical biosensor based on the micro ring resonator was a hotspot direction of the current research.LinRong's group of digestive system department in Union hospital of the Tongji medical college,was researching the process for bone marrow stromal stem cells cancerous caused stomach cancer.They found "bone marrow stromal stem cells(MSCs)have two different cell subsets”,and first proposed MSCs participated in the gastric cancer through the phenotypic transformation between different cell subsets.But due to the lack of specific markers,general biology method was hard to identify and distinguish the cell subsets.In this paper,the high sensitivity biosensor based on micro ring resonator was studied.Using the characteristic of micro ring resonator that it was sensitive to the background refractive index,to distinguish different cell-tissue fluid samples.Firstly,introduced the structure and characteristic parameters of micro ring resonator,coupling area of the micro ring and transmission characteristics were studied combined with the principle of optical waveguide and the coupled-mode theory of optical waveguide.What's more,main parameters were deduced including FSR,high Q value and half width calculation formula according to the parametric model of the micro ring resonator.Secondly,the principle that the micro ring resonator could be used as a biosensor was introduced in detail,and the main parameters such as equivalent FSR deduction of and detection sensitivity were deduced.Cascaded micro-ring biosensor structure was designed,using vernier effect to improve the detection sensitivity.The equivalent FSR and the detection sensitivity of cascaded micro-ring was derived on theory.Good quality cascaded micro-ring biosensor was fabricated,and larger equivalent FSR was obtained.Compared to common single micro ring sensor,not only the effective detection range was increased,also the detection sensitivity was improved.The ionized water,1640 culture medium,supernatant sample of gastric cancer cells that was cultivated three days and the two cell subsets of bone marrow stromal stem cells(MSCs)were tested respectively.The shift of the primary resonance peak wavelength of the cascaded micro-ring's output spectrum for 1640 culture medium and supernatant sample of gastric cancer cells is 16.2nm,and for the two cell subsets of bone marrow stromal stem cells(MSCs)is 17.48 nm.Intuitively distinguished for 1640 culture medium and supernatant sample of gastric cancer cells,the two cell subsets of bone marrow stromal stem cells(MSCs)on the primary resonance peak wavelength of the cascaded micro-ring's output spectrum.This article taking advantage of the highly-sensitive,ultra-compact and sensitive to refractive index of the micro ring resonator,to distinguish different cell-tissue fluid samples.The research helped the cooperation for biomedical research studies of gastric cancer mechanism.Highly-sensitive cascaded micro-ring biosensor was designed and fabricated,and the sensitivity of the cascaded micro-ring biosensor was 235nm/RIU. |
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