Infection of Kauri dieback occurs when oospores of P. agathidicida in soil or plant debris germinate, producing sporangia, which then release motile asexual zoospores into the immediate environment (Figure ). These zoospores subsequently infect the sensitive, feeder roots of kauri trees eventually spreading to the main roots and lower trunk. Once the lower trunk is affected, bleeding lesions or cankers develop, progressively encircling the trunk and leading to girdling and eventual tree demise. There is as yet no established treatment for infected trees and most kauri trees infected with P. agathidicida will ultimately perish. Therefore, the real-time detection of zoospores is critical in not only determining the presence and subsequent management of the pathogen, but also in understanding their physiology, such as how zoospores interact with the local microenvironment, what their distribution pattern is and how they communicate with each other. However, due to the small size of the zoospore (8 to 12 µm), high motility and their relatively low concentration in the field, it is challenging to detect them using currently available techniques such as soil-baiting or molecular-based qPCR assays. In recent years, microfluidic-based sensors have been developed as cytometers for cell counting. Their core part is a microchannel with paired microelectrodes, normally pre-patterned on the substrate, inside the channel. The passing of cells driven by a syringe pump triggers a change in impedance measured between the two electrodes, , as has been analysed in detail by Sun and Morgan. However, these studies are mainly limited to cells and polymeric beads and haven't been used for motile targets, such as the zoospores. Importantly, as the targets are typically carried by a flow driven by a syringe pump, one significant limitation associated is the non-specificity. When using such platforms for zoospore sensing, a variety of micro-objects, such as dust particles, microfibres and other small organisms, can be carried by the flow, be non-specifically introduced into the sensing channel and trigger an impedance change. Several strategies can be used to minimise the nonspecific sensing signals, including a pre-purification step of the sampling solution, flow-rate controlled separation of particles based on their physical properties (such as different densities) and signal filtrations based on the different signatures, such as amplitude and duration of the peak, recorded from different targets. These strategies minimise detection of fault signals, however differentiating signals from targets of similar impedance and physical properties, such as between different zoospore species, or between encysted vs. nonencysted zoospores, is still challenging.