Development of 3D-structured tilt capillary valve for lab-on-a-disc devices

Lab-on-a-disc (LoD) devices utilize centrifugal force to regulate fluid movement and are widely employed in biochemical applications. LoDs facilitate biochemical analysis by integrating different essential steps such as mixing samples and reagents, separating target components from the sample, and detecting analytes in a single platform. This integration on a single disc substrate enables the miniaturization and automation of various biochemical workflows. However, current LoD systems frequently rely on active valves, which increase complexity and limit versatility. To address these challenges, this study employed 3D printing technology to develop a 3D-structured tilt capillary valve acting as a passive control mechanism. Tilt capillary valves with inclination angles ranging from 50° to 80° were fabricated, and their burst rotational speeds and repeatability were compared with those of conventional capillary and slope valves. The tilt capillary valve demonstrated superior performance, achieving high-speed fluid control with relative standard deviations ranging from 1.5% to 2.1%. This improvement was attained by distributing the effects of centrifugal and gravitational forces along the inclined flow path. Additionally, the capillary structure stabilized the effects of surface tension, further enhancing reproducibility. These findings suggest that the developed tilt capillary valve enhances the LoD system performance, enabling more precise and rapid fluid control. The enhanced passive valve presented in this study can be incorporated in advanced microfluidic device designs, opening new possibilities for biochemical assays, particularly in resource-limited environments.