Microbiochips, such as a lab-on-a-chip (LOC) devices and micro total analysis systems, can be regarded conceptually as a biological equivalent of conventional silicon integrated circuits, which involve miniaturization and integration of electronics. As its name implies, an ideal LOC should have a very small footprint and yet still be capable of functioning as a laboratory in which partial or complete chemical or biological analysis can be performed automatically. This book provides an overview of 3D femtosecond laser direct writing technology and highlight its potential for fabrication of complex smart microsystems by furnishing some examples of fabrication and hybrid integration of microfluidics, micromechanics, photonics, and electronics.