为了准确在线测量微生物燃料电池(MFC)内Fe3+的浓度，基于倏逝波原理研制了一种D形塑料光纤Fe3+浓度传感器。采用静电层层自组装技术，将含有Fe3+指示剂的材料组装在D形光纤表面，构成Fe3+敏感区。实验研究表明: 传感器的灵敏度、响应时间与敏感膜的厚度和指示剂的含量有关。当Fe3+敏感膜自组装层数为20层时，传感器对含Fe3+离子溶液浓度为0.01mol·L-1的响应时间约13min，最低检测极限达10-6mol·L-1，表明该传感器对Fe3+离子水溶液具有良好的光学响应性能。

To accurately measure the Fe3+ concentration existing in microbial fuel cell (MFC), a plastic optical fiber (POF) evanescent wave sensor with D-shape structure was put forward. The Fe3+ indicator sensitive film was deposited on the surface of POF through layer-by-layer(L-b-L) electrostatic self-assembly technique as indicator to the concentration of Fe3+. Experimental results illustrate that the sensitivity and response time are related to the number of sensitive film layers and the content of indicator. When the layer number is 20, the response time is about 13min, and the minimum detection limit hits 10-6mol·L-1. The results show that the sensor has good optical response to Fe3+ aqueous solution.