Femtosecond Laser Direct Writing for 3D Microfluidic Biochip Fabrication

Microfluidic devices with three-dimensional (3D) configurations and multiple functionalities are exceptionally useful for on-chip construction of artificial biological environments and 3D manipulation of bio-species in microscale spaces. Among the current methods for fabricating these devices, femtosecond (fs) laser direct writing offers several unique advantages, including simple procedures, maskless and resistless processing, and highly flexible 3D fabrication and multifunctional integration in transparent materials such as glass. Direct writing of 3D microstructures having designable functionalities with fs lasers allows the production of microfluidic, microoptic/photonic and microelectronic elements, which can be monolithically integrated into a single glass substrate for the fabrication of high-performance biochips. The principles of fs laser direct writing manufacture of microfluidic, optofluidic, electrofluidic, and ship-in-a-bottle biochips are introduced herein, and practical techniques and recent advances are reviewed. In addition, possible future directions in this field are discussed.