Development of a Mediator-Type Bioelectrochemical Sensor Based on Polypyrrole Immobilized Ferricyanide and Microorganisms for Biochemical Oxygen Demand Fast Detection

A mediator-type bioelectrochemical sensor was developed by using polypyrrole (PPy) immobilized ferricyanide (FC) as mediator and immobilized Pseudomonas aeruginosa (P. aeruginosa) as a biosensing film for biochemical oxygen demand (BOD) fast detection. The sensor chip consists of a three-electrode system, with Au working electrode (WE), Pt counter electrode (CE) and Pt pseudoreference electrode (RE) compactly integrated as a disposable using micro-electro-mechanism system (MEMS) technology. The FC mediator and P. Aeruginosa microorganisms have been embedded in PPy matrix on gold microelectrode surface during the electropolymerization of pyrrole monomer using electrochemical cyclic voltammetry (CV) method. This bioelectrochemical sensor responds to BOD due to yielded ferrocyanide during catalytic reduction by metabolic reactions of microorganisms. A good linear correlation with chemically determined BOD values was obtained from 5 to 100 mg/L with fast response time. The proposed sensor in this paper is significant for BOD fast detection.