Programmable optical window bonding enabled 3D printing of high-resolution transparent microfluidic devices for biomedical applications

Traditional technologies for manufacturing microfluidic devices often involve the use of molds for polydimethylsiloxane (PDMS) casting generated from photolithography techniques, which are time-consuming, costly, and difficult to use in generating multilayered structure. As an alternative, 3D printing allows rapid and cost-effective prototyping and customization of complex microfluidic structures. However, 3D-printed devices are typically opaque and are challenging to create small channels. Herein, we introduce a novel "programmable optical window bonding" 3D printing method that incorporates the bonding of an optical window during the printing process, facilitating the fabrication of transparent microfluidic devices with high printing fidelity. Our approach allows direct and rapid manufacturing of complex microfluidic structure without the use of molds for PDMS casting. We successfully demonstrated the applications of this method by fabricating a variety of microfluidic devices, including perfusable chips for cell culture, droplet generators for spheroid formation, and high-resolution droplet microfluidic devices involving different channel width and height for rapid antibiotic susceptibility testing. Overall, our 3D printing method demonstrates a rapid and cost-effective approach for manufacturing microfluidic devices, particularly in the biomedical field, where rapid prototyping and high-quality optical analysis are crucial.