Aerogel is a broad term used to talk about an extraordinary group of materials that have been used since the 1960s in space travel, but are now finding uses across a whole range of industries. ‘Aerogel’ is not a specific mineral or material with a set chemical formula-rather, the term is used to encompass all materials with a specific geometrical structure. This structure is an extremely porous, solid foam, with high connectivity between branched structures of a few nanometres across.

Though aerogel is technically a foam, it can take many different shapes and forms. The majority of aerogel is composed of silica, but carbon, iron oxide, organic polymers, semiconductor nanostructures, gold and copper can also form aerogel. However, within the aerogel structure, very little is solid material, with up to 99.8% of the structure consisting of nothing but air. This unique composition gives aerogel an almost ghostly appearance; hence it is often referred to as ‘frozen smoke’.