Femtosecond Laser Fabrication of Microchannels in Transparent Hard Materials

The excellent characteristics of transparent hard materials such as high hardness, high transparency, corrosion resistance, and high temperature resistance enable their applications in microfluidic substrates even in harsh environments. Microchannels are important parts in microfluidic systems, and the preparation of microchannel structures in transparent hard materials deserves further in-depth study. The traditional processing method is contact processing with large thermal influence and low processing efficiency, so it is impossible to obtain complex microchannels with high quality and high aspect ratio. The femtosecond laser processing is a non-contact processing approach with no thermal damage, high processing accuracy, and easy to form complex microchannels, making it the best choice for processing microchannels in transparent hard materials. This work reviews the recent advances in femtosecond laser processing of transparent hard materials to form microchannel structures, focusing on the reaction mechanism, processing methods, and the obtained microchannel structures, including surface microchannels, 2D microchannels, and 3D microchannels. Furthermore, the application of microchannel structure in microfluidic field, including optical inspection and biochemical reaction, is also described.