Influence of membrane type, current and potential on the response to chemical toxicants of a microbial fuel cell based biosensor

Drinking water free of chemical toxicants is important for people's health. A microbial fuel cell based biosensor can be used to detect the presence of toxic chemicals. The sensitivity of this type of biosensor for nickel was investigated. There was no delay in the response of the sensor and the sensitivity was 0.0027 A/m2/mg Ni/l at an anode potential of -0.4 V. The effect of four types of ion exchange membranes (cation exchange, anion exchange, monovalent cation exchange and bipolar membranes) on the sensitivity was not significant. Current density correlates with the decrease of the nickel concentration in the sensor with 16.5 mg/l/A/m2 by causing a flux of nickel towards the membrane and the catholyte. However, the sensitivity is higher at higher overpotential and thus at higher current density. Thus although nickel concentration is lower, the response is higher at high overpotentials. The sensitivity still has to be increased because even at an overpotential of -0.16 V the sensitivity is too low to be able to measure the concentrations that is maximally allowed by European directives on (drinking) water quality.