Microfluidics refers to the science and technology of manipulating and controlling fluids in designs with dimensions ranging from tens to hundreds of micrometers, covering fluid volumes from microliters to picoliters. Compared to traditional fluid studies and techniques, microfluidics offers several advantages, including low-cost experiments, minimal volume consumption, reduced analysis and reaction times due to shorter diffusion distances, increased surface-to-volume ratio, multiplexing capabilities, portability, versatile design integration, reproducibility, and automation. However, hydrodynamic principles established at the macro-scale need to be reconsidered at the micro-scale. For instance, gravity forces become insignificant compared to capillary forces, and the influence of surfaces becomes more significant. At the micro-scale, viscosity takes precedence over inertial forces, resulting in laminar flows, where turbulence is not spontaneous. Consequently, when two liquids are injected side by side, they will only mix through diffusion in a direction perpendicular to the flow.

Extracellular vesicles (EVs) emerge as fascinating lipid bilayer micelles released by virtually every cell across living organisms, holding immense potential as biomarkers, particularly in the realm of cancer diagnostics. These microcarriers facilitate the transfer of crucial biological information, encapsulating proteins, lipids, and nucleic acids as they traverse the extracellular space, orchestrating cellular communication. Among the diverse spectrum of EVs, exosomes stand out, characterized by their size range of 50 to 200 nanometers and originating from the multivesicular body. Renowned as highly promising biomarkers, exosomes harbor a distinct fingerprint of their parent cell, making them valuable indicators for diagnostic exploration and potential therapeutic advancements in various medical contexts. 

Personalized treatment for cancer has the potential to adapt to the diverse nature of cancer, enhancing the effectiveness of drugs while reducing their toxicity. Within this strategy, liquid biopsy offers a new non-invasive approach for cancer diagnosis, treatment guidance, and treatment monitoring. Clinical research in liquid biopsy primarily concentrates on three biomarkers: circulating tumor cells (CTC), circulating tumor DNA (ctDNA), and tumor-derived extracellular vesicles or exosomes.