Direct Writing of Microfluidic Three-Dimensional Photonic Crystal Structures for Terahertz Technology Applications.

The direct writing technology was used to create microfluidic three-dimensional terahertz photonic crystal structures (3D-TPCSs) with a glass cement ink, which demonstrated potentials for various terahertz technology applications. By a simple injection of liquid alloy into them, metallic 3D-TPCSs could be created easily at a low cost to solve the challenges of their creation by current approaches. These microfluidic 3D-TPCSs also possessed a specific capability of changing their terahertz properties in real time without structural changes by injecting fluidic media with different dielectric properties into their microfluidic channels, which endowed them the easy integration into various terahertz devices that require terahertz modulation for a wide range of applications. Due to their microsized channel structure and subsequent reduction of terahertz irradiation absorption by water in them, they demonstrated the potential as real time, nondestructive biological and chemical sensors to detect changes occurring in them in the fluidic media with the terahertz time-domain spectroscopy (THz-TDS).