Binary centrifugal microfluidics enabling novel, digital addressable functions for valving and routing

Abstract

Centrifugal microfluidics or lab-on-a-disc (LOAD) is a promising branch of lab-on-a-chip or microfluidics. Besides effective fluid transportation and inherently available density-based sample separation in centrifugal microfluidics, uniform actuation of flow on the disc makes the platform compact and scalable. However, the natural radially outward centrifugal force in a LOAD system limits its capacity to perform complex fluid manipulation steps. In order to increase the fluid manipulation freedom and integration capacity of the LOAD system, we propose a binary centrifugal microfluidics platform. With the help of Euler force, our platform allows free switching of both left and right states based on a rather simple mechanical structure. The periodical switching of state would provide a "clock" signal for a sequence of droplet binary logic operations. With the binary state platform and the "clock" signal, we can accurately handle the droplet separately in each time step with a maximum main frequency of about 10 S s-1 (switching per second). Apart from droplet manipulations such as droplet generation and metering, we also demonstrate a series of droplet logic operations, such as binary valving, droplet routing and digital addressable droplet storage. Furthermore, complex bioassays such as the Bradford assay and DNA purification assay are demonstrated on a binary platform, which is totally impossible for a traditional LOAD system. Our binary platform largely improves the capability for logic operation on the LOAD platform, and it is a simple and promising approach for microfluidic lab-on-a-disc large-scale integration.

Mathematical modeling and computational analysis of centrifugal microfluidic platforms: a review

“…Five years later, Wang et al proposed another mechanical structure to affect the movement between the two temperature zones. 122 They used the Euler force for droplet generation, metering, and droplet manipulations. The system is shown in Fig.…”

“…The researchers also used this method for two specific applications of DNA purification and Bradford assay. 122 The detailed computational analyses explained in the previous sections are not necessarily straightforward. Although they can provide in-depth information about the phenomena in all the different unit operations, they need highly trained users with a background in programming and enough run time.…”

“…This device works based on the balance of centrifugal and Euler forces, which, according to the theoretical diagrams, happened at 300 rpm and 3000 rpm s −1 in this work. 122 Reproduced with permission from the Royal Society of Chemistry.…”

Droplet and Particle Generation on Centrifugal Microfluidic Platforms: A Review

“…The use of external pumps such as syringe and peristaltic pumps are common in the field of microfluidics since they are easy to use. Generally, external pumps are expensive and each reagent in the assay requires a separate pump, which makes the experimental setup even more expensive [28]. These pumps are large and need a lot of external complex interconnects [28,29], which does not make them the best candidates for POC applications.…”

“…Generally, external pumps are expensive and each reagent in the assay requires a separate pump, which makes the experimental setup even more expensive [28]. These pumps are large and need a lot of external complex interconnects [28,29], which does not make them the best candidates for POC applications. In addition, since they are external pumps, they need long tubing systems for connecting to inlets and outlets, which requires high upstream pressures and wastes a lot of precious sample material as tubing dead volumes [30,31].…”