Definition of a Microsphere:
There is a lot of confusion and uncertainty in the academic community as well as the industry on exactly what is a microsphere. Below is the definition of “microsphere” that we use, because it is clear and straight-forward:
Microsphere is a term used for a small solid spherical particle, with diameter in the micrometer range (typically 1 micron to 1000 micron (1mm)).
What a Microsphere is Not:
A microsphere is not the same as a microcapsule, because microcapsules typically consist of a flexible (deformable) shell encapsulating a fluid, which might be liquid or gas. Microspheres always have a solid shell. Even if the microsphere is technically hollow (containing gas inside), its shape is not significantly flexible or deformable.
A microsphere is not the same as a microparticle, because microparticle is a general term that refers only to the size of the granular material and does not provide information on the shape. Microspheres are always round and spherical. There are no sharp edges, oblong shapes, or debris.
A microsphere is not the same as a nanopshere, because nanospheres have diameters on the nanoscale (typically between 1 nanometer and 1000 nanometers (1 micron)). Nano-diameters present a complete different characteristics, behaviors, and functionalities.
What are Microsphere Materials:
Microspheres are manufactured from various natural and synthetic materials. Glass microspheres, polymer microspheres, and ceramic microspheres are commercially available. Solid and hollow microspheres vary a lot in density and, therefore, are used for different applications. Hollow microspheres are typically used as additives to lower the density of a material. Solid microspheres have numerous applications depending on what material they are constructed of and what size they are.