A renewable BOD microsensor based on magnetically functionalized microorganism and ultramicroelectrode array

This paper presents a renewable biochemical oxygen demand (BOD) microsensor based on a sensing element of magnetically functionalized microorganism and a transducer of ultramicroelectrode array (UMEA). Different from the traditional BOD sensor which includes an immobilized microbial film, the magnetically functionalized microorganism was retained on the UMEA with a permanent magnet to simplify the modification process and renew the microbial film. After respiration of microorganism, the UMEA was used to detect the concentration change of dissolved oxygen (DO). The microsensor showed a linear range from 2 to 20 mg/L, with a correlation coefficient of 0.985. The sensitivity of this microsensor was increased due to the specific structure without multilayer membrane reducing mass transfer resistances and the outstanding electrochemical characteristics of UMEA for detecting of DO change. The regeneration of the BOD microsensor is satisfied because the microorganism can be easily renewed by the magnet after detection.