Nanoaquarium fabricated by femtosecond laser 3D micromachining: Investigation on phormidium assemblage

Internal modification of transparent materials such as glass can be carried out using multiphoton absorption induced by a femtosecond (fs) laser. The fs-laser modification followed by thermal treatment and successive chemical wet etching in a hydrofluoric (HF) acid solution forms three-dimensional (3D) hollow microstructures embedded in photosensitive glass. This technique is a powerful method for directly fabricating 3D microfludic structures integrated with some functional microcomponents inside a photosensitive glass microchip. We used the fabricated microchips, referred to as a nanoaquarium, for dynamic observations of living microorganisms. In this paper, among some examples, we focus on exploring mechanism of Phormidium assemblage to seedling root for growth promotion of vegetable using the nanoaquarium.