A method for the detection of target entities, the method including: introducing a liquid sample containing at least one type of target entity to be detected into a fluidic channel; wherein mutually spaced electrodes functionalised to selectively bond to the at least one type of target entity are disposed along the fluidic channel to electro-hydrodynamically pump the liquid sample along the fluidic channel on application of a signal to the electrodes so that induced charges in the double layer of each electrode experience a force F = ρ E, where ρ = charge density, due to interaction with the tangential component of the applied electric field E, and produce a fluid flow; selecting one or more values for respective parameters of an AC or DC signal to be applied to the electrodes wherein at least one of the one or more selected values is a corresponding optimum value to provide enhanced selectivity of the at least one type of target entity by selectively shearing non-specifically adsorbed cells and/or molecules from the electrodes resulting from the fact that the fluid is driven by forces applied at nanometer distances from the electrode surface where the attachment and capture of entities also occurs, and the corresponding ability to control or at least correspondingly modify or determine highly localised electrohydrodynamic shear forces that are induced by the applied DC or AC signal within the double layer formed on the surface of the electrodes, the one or more parameters of the signal being, in the case of an AC signal, its frequency, signal amplitude, and signal shape/form, or in the case of a DC signal, its amplitude; and applying a signal having the selected one or more values for the respective one or more parameters to the electrodes to pump the liquid sample along the fluidic channel and to selectively shear the non-specifically adsorbed cells and/or molecules from the functionalised electrodes. introducing a liquid sample containing at least one type of target entity to be detected into a fluidic channel; wherein mutually spaced electrodes functionalised to selectively bond to the at least one type of target entity are disposed along the fluidic channel to electro-hydrodynamically pump the liquid sample along the fluidic channel on application of a signal to the electrodes so that induced charges in the double layer of each electrode experience a force F = ρ E, where ρ = charge density, due to interaction with the tangential component of the applied electric field E, and produce a fluid flow; selecting one or more values for respective parameters of an AC or DC signal to be applied to the electrodes wherein at least one of the one or more selected values is a corresponding optimum value to provide enhanced selectivity of the at least one type of target entity by selectively shearing non-specifically adsorbed cells and/or molecules from the electrodes resulting from the fact that the fluid is driven by forces applied at nanometer distances from the electrode surface where the attachment and capture of entities also occurs, and the corresponding ability to control or at least correspondingly modify or determine highly localised electrohydrodynamic shear forces that are induced by the applied DC or AC signal within the double layer formed on the surface of the electrodes, the one or more parameters of the signal being, in the case of an AC signal, its frequency, signal amplitude, and signal shape/form, or in the case of a DC signal, its amplitude; and applying a signal having the selected one or more values for the respective one or more parameters to the electrodes to pump the liquid sample along the fluidic channel and to selectively shear the non-specifically adsorbed cells and/or molecules from the functionalised electrodes.