Photolithography-free fabrication of photoresist-mold for rapid prototyping of microfluidic PDMS devices

Lab-on-a-chip: an advanced technology for the modernization of traditional Chinese medicine

Benefiting from the complex system composed of various constituents, medicament portions, species, and places of origin, traditional Chinese medicine (TCM) possesses numerous customizable and adaptable efficacies in clinical practice guided by its theories. However, these unique features are also present challenges in areas such as quality control, screening active ingredients, studying cell and organ pharmacology, and characterizing the compatibility between different Chinese medicines. Drawing inspiration from the holistic concept, an integrated strategy and pattern more aligned with TCM research emerges, necessitating the integration of novel technology into TCM modernization. The microfluidic chip serves as a powerful platform for integrating technologies in chemistry, biology, and biophysics. Microfluidics has given rise to innovative patterns like lab-on-a-chip and organoids-on-a-chip, effectively challenging the conventional research paradigms of TCM. This review provides a systematic summary of the nature and advanced utilization of microfluidic chips in TCM, focusing on quality control, active ingredient screening/separation, pharmaceutical analysis, and pharmacological/toxicological assays. Drawing on these remarkable references, the challenges, opportunities, and future trends of microfluidic chips in TCM are also comprehensively discussed, providing valuable insights into the development of TCM.

Microfluidics: a concise review of the history, principles, design, applications, and future outlook

Microfluidic technologies have garnered significant attention due to their ability to rapidly process samples and precisely manipulate fluids in assays, making them an attractive alternative to conventional experimental methods. With the potential for revolutionary capabilities in the future, this concise review provides readers with insights into the fascinating world of microfluidics. It begins by introducing the subject's historical background, allowing readers to familiarize themselves with the basics. The review then delves into the fundamental principles, discussing the underlying phenomena at play. Additionally, it highlights the different aspects of microfluidic device design, classification, and fabrication. Furthermore, the paper explores various applications, the global market, recent advancements, and challenges in the field. Finally, the review presents a positive outlook on trends and draws lessons to support the future flourishing of microfluidic technologies.

Breaking the clean room barrier: exploring low-cost alternatives for microfluidic devices

Microfluidics is an interdisciplinary field that encompasses both science and engineering, which aims to design and fabricate devices capable of manipulating extremely low volumes of fluids on a microscale level. The central objective of microfluidics is to provide high precision and accuracy while using minimal reagents and equipment. The benefits of this approach include greater control over experimental conditions, faster analysis, and improved experimental reproducibility. Microfluidic devices, also known as labs-on-a-chip (LOCs), have emerged as potential instruments for optimizing operations and decreasing costs in various of industries, including pharmaceutical, medical, food, and cosmetics. However, the high price of conventional prototypes for LOCs devices, generated in clean room facilities, has increased the demand for inexpensive alternatives. Polymers, paper, and hydrogels are some of the materials that can be utilized to create the inexpensive microfluidic devices covered in this article. In addition, we highlighted different manufacturing techniques, such as soft lithography, laser plotting, and 3D printing, that are suitable for creating LOCs. The selection of materials and fabrication techniques will depend on the specific requirements and applications of each individual LOC. This article aims to provide a comprehensive overview of the numerous alternatives for the development of low-cost LOCs to service industries such as pharmaceuticals, chemicals, food, and biomedicine.

Validation of Easy Fabrication Methods for PDMS-Based Microfluidic (Bio)Reactors

The common method for producing casting molds for the fabrication of polydimethylsiloxane (PDMS) chips is standard photolithography. This technique offers high resolution from hundreds of nanometers to a few micrometers. However, this mold fabrication method is costly, time-consuming, and might require clean room facilities. Additionally, there is a need for non-micromechanics experts, who do not have specialized equipment to easily and quickly prototype chips themselves. Simple, so-called, makerspace technologies are increasingly being explored as alternatives that have potential to enable anyone to fabricate microfluidic structures. We therefore tested simple fabrication methods for a PDMS-based microfluidic device. On the one hand, channels were replicated from capillaries and tape. On the other hand, different mold fabrication methods, namely laser cutting, fused layer 3D printing, stereolithographic 3D printing, and computer numerical control (CNC) milling, were validated in terms of machine accuracy and tightness. Most of these methods are already known, but the incorporation and retention of particles with sizes in the micrometer range have been less investigated. We therefore tested two different types of particles, which are actually common carriers for the immobilization of enzymes, so that the resulting reactor could ultimately be used as a microfluidic bioreactor. Furthermore, CNC milling provide the most reliable casting mold fabrication method. After some optimization steps with regard to manufacturing settings and post-processing polishing, the chips were tested for the retention of two different particle types (spherical and non-spherical particles). In this way, we successfully tested the obtained PDMS-based microfluidic chips for their potential applicability as (bio)reactors with enzyme immobilization carrier beads.