Research On Optofluidic-Microcavity Interference Sensor

Optofluidic-microcavity sensing technology has emerged as a dynamic and rapidly developing research field, which combines microfluidic technology and optical microcavity and greatly takes advantage of both. On the one hand, it takes advantage of the perfect optical properties of the optical microcavity, such as a high Q value, small size, easy to system integration; on the other hand, it plays the advantages of microfluidic technology, such as the ability to convenient fluid samples control, and optical detection simultaneously. The development of optofluidic-microcavity sensing technology has enormous potential impact on many fields, it has been widely used in biological and chemical detection and analysis area. Optofluidic-microcavity sensor has many advantages in applications, such as high resolution and high sensitivity detection, low sample consumption, the easy handling of sample and reagent by using fluid, quick response and analysis, the analyzer miniaturized, easy to system integration, and strong multiplexing.In this paper, we carry out research work on optofluidic-microcavity sensor by using optofluidic ring resonator as the experimental platform, and have achieved a passive flow rate sensing and active graphene oxide detection:(1) In recent years, microfluidic technology has become a hot research topic, and been widely applied to biochemical analysis, such as flow cytometry, drug testing, etc. In these applications, the microfluidic flow rate plays an important role. Therefore, precise measurement and control of flow rate is very meaningful. We demonstrate an optofluidic flow rate sensor based on the heat transfer effect in a microfluidic channel for the lab-on-a-chip applications. By employing an optofluidic ring resonator (OFRR), the wavelength shift of the resonant dip of the whispering gallery mode is detected as a function of the flow rate. A measurement range of 2-100 μL/min, a minimum detectable change of 30 nL/min, and an accuracy of 5.2% for the flow rate detection are achieved. This OFRR flow rate sensor has good repeatability, and the inverse sensitivity is beneficial for detecting the low flow rate with high sensitivity. It has a significant advantage in combination with microfluidic channel especially for capillary-based microfluidics.(2) In this paper, we demonstrate a detection technology of graphene oxide based on microfluidic laser. Aqueous solution of R6G is used as gain medium, quartz capillary with its wall thickness controlled to a few microns acts as microchannel and also works as a ring resonator which provides an excellent optical feedback for laser. Upon the reaction between GO and R6G, the charge-transfer complex forms and significant laser quenching is observed. The concentration of GO is detected by laser quenching effect of GO. By choosing different concentrations of R6G, dynamic change of the measurement range for GO detection can be realized. A GO concentration detection of 0-300 μg/ml is realized by using a R6G concentration of 200μg/ml in the experiment, covering the focus concentration range for GO biological compatibility research. We believe that it will have a great application prospect.