Contamination of water by pathogens particularly Escherichia Coli (E. coli) presents a major challenge to human health today. These outbreaks not only burden healthcare systems but result in major financial and reputational damage to governments and water-treatment industries. The economic cost of managing impacts and plant shutdowns can be avoided by timely detection of the bacteria but most conventional techniques are labour intensive, time consuming and require high pathogen concentrations for effective detection. In this work, we capture and quantify outer membrane vesicles (OMVs) released by E. coli cells. As cellular excreta, these vesicles exhibit similar outer membrane proteins, composition and characteristics of the parent bacterial cell and can be used as abundant alternative targets1 for E. coli detection. In doing so, we exploit specific DNA aptamers that selectively bind to the surface of OMVs, while examining their surface interactions and binding affinity to aid sensitive and efficient capture. In conjunction, we develop a dual detection platform that combines impedance based electrical and optical measurements to allow for rapid, robust and cost-effective detection of E. coli OMVs in potential industrial applications.