Effect of shear rate on the response of microbial fuel cell toxicity sensor to Cu(II)

► The sensitivity of MFC sensors to toxicants is affected by the biofilm structure. ► Most influential parameters of MFC sensitivity: biofilm porosity, density and EPS. ► Low flow rate reduced the biofilm density and increased its porosity. ► Intermittent nitrogen sparging reduced the EPS content of the biofilm. ► Low flow rate and intermittent nitrogen sparging increased the sensitivity of MFC.