Microparticle

Microparticle refers to a small particle whose linear dimension lies in the micrometer range, typically from about 1 μm to 1000 μm (1 mm). The term is used across disciplines such as physics, chemistry, environmental science, and engineering. Microparticles may be solid or hollow, inorganic or organic, and can occur naturally (dust, pollen, fungal spores, volcanic ash) or be anthropogenic (industrial aerosols, pigment particles, microbeads).

Size, composition, and surface properties determine microparticle behavior in air or liquid. Settling velocity and transport follow appropriate fluid-dynamic regimes; surface charge and hydrophobicity influence aggregation and stability; optical properties enable detection by light scattering. Brownian motion is more pronounced for smaller microparticles, while larger ones experience stronger sedimentation and filtration. Microparticles can be detected and characterized by microscopy, spectroscopy, and particle-sizing techniques, and their presence is a common focus in air and water quality assessments.

Applications and relevance span several fields. In medicine, microparticles serve in drug delivery systems, diagnostic assays, imaging, and vaccine adjuvants. In materials science, they function as fillers, pigments, or catalysts supports, and are used in microencapsulation and coatings. In environmental science, monitoring and regulation of particulate matter (for example PM10 and PM2.5) rely on understanding microparticle properties and dynamics. In industry, microparticles are used in printing, cosmetics, and various manufacturing processes.

Measurement and characterization methods include optical and electron microscopy for morphology, sieve analysis for coarser fractions, laser diffraction or aerodynamic particle sizing for size distribution, Coulter counting for particle counts, and gravimetric methods for mass concentration.