Trends in 3D Manufacturing of Microdevices for Biomedical Applications

Over the past decades, microfabrication technologies have been essential tools in the creation and fabrication of biomedical microfluidic devices useful for diagnostics, biosensing, drug delivery, and organ-on-a-chip applications. Soft lithography is one of the most widely used conventional microfabrication techniques and can achieve a high resolution (~100 nm) and excellent fidelity of the replica but requires a high level of expertise, expensive equipment, and access to cleanrooms, which is not widely available and makes it difficult to scale up and adopt. Moreover, the material limitations and the complicated fabrication steps of conventional lithographic methods limit the fast prototyping of advanced microfluidic platforms. These limitations have been overcome in recent years with the integration of 3D printing and soft lithography, and, now, the rapid, cost-effective, and customizable fabrication of high-quality master molds of PDMS-based microfluidic devices is possible. Modern 3D printing technologies provide great material versatility, design flexibility, high manufacturing efficiency, and a much shorter and lower cost of fabrication. This review critically discusses the recent advancements of the 3D printing-assisted soft lithography method in biomedical microfluidic device fabrication, focusing on fabrication techniques, materials for 3D printing, hybrid fabrication strategies, and representative biomedical applications. Moreover, the current developments of high-resolution additive manufacturing, multi-material fabrication, and eco-friendly manufacturing are discussed, and insights into the future development of next-generation bio-medical microfluidic systems are provided.