Microparticles are particles between 0.1 and 100 μm in size. Commercially available microparticles are available a wide variety of materials, including those made of ceramics, glass, polymers, and metals. One encounters microparticles everyday in nature with items such as pollen, sand, and dust. Many Microparticles can be found in your kitchen as well with items such as: flour, and powdered sugar.
Microparticles have a much larger surface-to-volume ratio than at the macroscale, and thus their behavior can be quite different. For example, metal microparticles can be explosive in air.
Microsphere are spherical microparticles, and are used where consistent and predictable particle surface area is important.
In biological systems, microparticles are small membrane bound vesicles circulating in the blood derived from cells that are in contact with the bloodstram such as platelets and endothelial cells. (see Endothelial microparticle). Because they retain the signature membrane protein composition of the parent cell, microparticles carry useful information and can be detected and characterized by Flow cytometry.