微悬臂梁生化传感系统的性能分析

在基于光杠杆原理检测微悬臂梁变形的生化传感实验系统中,液体折射率的变化会导致PSD上光斑的位移,从而影响系统的检测信号。本文从理论上分析了在不同检测光束的入射角度、微梁的放置角度等参数条件下,液体折射率的变化对系统检测信号的影响。结果表明：在传统的光路下,液体折射率改变10-3引起的光斑位移与一般的生化反应引起的位移相当,即液体折射率的改变严重影响系统的检测信号。通过理论分析还发现在适合的参数配置下,可以忽略折射率变化对系统检测信号的影响。同时,参数的改变不影响系统的检测灵敏度。理论分析的结果得到了实验验证。

Performance analysis of bio-chemical sensor system based on micro-cantilever

In a micro-cantilever bio-chemical sensor system based on optical lever, the change of liquid refractive index is able to cause the displacement of spot moving on PSD, which will affect the system signal detection. In this paper, the influence of refractive index change under different conditions such as the laser incidence angle, the angle between micro-cantilever and liquid surface is theoretically analyzed. Results show that the signal displacement (as small as 10^-3) caused by the refractive index change in a traditional optical design is corresponding to the reported cantilever deflection caused by the bio-chemical reaction. That is, the detected signals of system are greatly affected by the change of liquid refractive index. The results also show that the effect of refractive index change on the signal detection can be neglected under proper parameter condition without reducing system detecting sensitivity. This theoretical result was validated by experiments.