Fabrication of sealed sapphire microfluidic devices using femtosecond laser micromachining

Due to its hardness, strength, and transparency, sapphire is an attractive material for the construction of microfluidic devices intended for high-pressure applications, but its physiochemical properties resist traditional microfabrication and bonding techniques. Here a femtosecond pulsed laser was used to directly machine fluidic channels within sapphire substrates and to form bonds between machined and flat sapphire windows, resulting in the creation of sealed microfluidic devices. Sapphire-sapphire bond strength was determined by destructive mechanical testing, and the integrity of the bond was verified by the capillary filling of the channel with air and ethanol. This combination of optical micromachining and bonding establishes a fully integrated approach to the fabrication of sapphire-based microfluidic systems.