To enhance the detection and analysis of µm-size biological particles (like extracellular vesicles and exosomes) essential in the diagnosis of many diseases like sepsis and cancer, we developed a Flow-Cytometer-in-a-Fiber device that was able to reliably detect 1 µm fluorescent polystyrene beads. This technology allows a fast detection and identification of the different particles, paving the way for an advanced point-of-care diagnostic platform that could be used, for example, in cancer diagnostics. Furthermore, the small footprint of this device allows an easy integration with other existing diagnostic platforms.