A wax printed mold for prototyping microfluidic devices

In this paper, we proposed and demonstrated a facile process that leverages wax printing technology for fabricating high-resolution molds for microfluidic devices. Traditionally, microfluidic devices are made from photolithography-fabricated molds, involving complicated and expensive equipment, reagents, and highly skilled personnel. The process is time-consuming, hindering the widespread use of microfluidic devices. However, wax printing technology can directly print hundreds of micron-wide wax lines with certain heights onto smooth substrates, and these wax lines can directly be used as molds for microfluidic channels, thus completing the microfluidic devices. To date, this process has not been systematically studied and optimized. Here, we report the optimized wax printing process parameters (e.g., grayscale, printing times) and achieved a minimum 300 µm channel width for microfluidic channels. Though the line width cannot compete with the traditional photolithography process, this newly proposed method is inexpensive, fast, and highly automated, holding great potential for widespread use. Moreover, our approach boasts two unique features. Firstly, the half-circular mold shape optimally suits microfluidic channels. Secondly, the mold concurrently deposits a thin wax layer on microfluidic inner channel surfaces, preventing small molecule absorption-crucial for diverse microfluidic applications.