光纤倏逝波生物传感器探针新的几何设计

The New Taper Geometries Design of Fiber Optical Evanescent Wave Biosensor Probe

为提高光纤倏逝波生物传感器的探测效率和灵敏度,根据光纤的模式匹配理论计算了给定条件下光纤探头的模式匹配半径,以此匹配半径为基础分析激发光在线性锥型光纤探头中的光线传输轨迹。结合倏逝波透射深度与光线入射角之间的关系,提出一种新的抛物线锥形光纤探头。计算结果表明,为使入射光在均匀感应部分激发的能量最大,入射角在锥形感应部分必须满足在锥形终端最小且刚好是临界角的条件。通过修正抛物线锥形参数,使入射角在满足全反射条件下更加接近于临界角,从而获得比线性锥形更深的透射深度。灵敏度测试实验结果表明抛物线锥形的灵敏度比其它探针测试效果好,说明凹形抛物线锥形探针能够与待测的生物样品之间构成一种理想的荧光收集与激发机制,实验与理论结果比较吻合。

In order to enhance the detection efficiency of fiber optical evanescent wave biosensor, the excite light＇s transmission track in the probe of linear taper is analyzed based on the mode matching radius of fiber probe obtained according to the mode matching theory of fiber in given conditions. Combined with the relationship between evanescent wave penetration depth and incidence angle, a new parabola taper fiber probe is put forward. The calculation shows that to maximum the energy excited at uniform sensitive part, incident angle must be minimal at the end of taper and equal to critical angle. By modifying the parameter of parabola taper, incident angle is closer to the critical angle at the taper transition phase when it＇s still larger than the critical angle, which excites lager penetration depth. The experiment shows that the sensitivity of parabola taper is better than others, which indicates parabola taper can ideally collect and excite fluorescence, and theory matches with experiment well.