Pneumatic pumping in centrifugal microfluidic platforms

Abstract

Centrifugal microfluidics has emerged as a unique approach to the development of integrated total analysis systems for medical diagnostics. However, despite its many advantages, the platform has a size limitation due to the centripetal pumping mechanism in which fluids can only be moved from the center of the disc to the rim. This limits the footprint of the microfluidic network to one radius of the disc, and this in turn limits the amount of space available to embed complex assays. In order to overcome this space limitation problem, we are developing new techniques to pump fluids back toward the center of the disc as to allow greater path lengths for the fluidic network. This study presents a novel pumping mechanism for centrifugal microfluidics utilizing a combination of centrifugation and pneumatic compression. Pneumatic energy is stored during high-speed centrifugation with sample fluids trapping then compressing air in specially designed chambers. The accumulated pneumatic energy is released by spinning down, which expands the trapped air and thus pumps liquids back toward the center of the CD. This newly developed method overcomes current limitations of centripetal pumping avoiding external manipulation or surface treatments. In this article, we explore the design of appropriate chambers to induce pneumatic pumping and analytically describe the mechanics behind the pumping action. For proof of principle, we have applied pneumatic pumping to siphon priming.

Euler force actuation mechanism for siphon valving in compact disk-like microfluidic chips

“…To avoid surface treatments, Madou et al has proposed the pneumatic pumping technique. 6 In addition, the pneumatic pumping technique has been applied to the comprehensive integration of homogeneous bioassays achieved by Ducree et al 4 However, the pneumatic pumping technique has typically prevented highly integrated processing because of the need of the volume-occupied compressed FIG. 13.…”

“…To avoid the surface treatment and external manipulation of plastics, several new actuation mechanisms have been proposed to optimize the use of real estate on a CD-like chip. These new mechanisms include pneumatic pumping, 6,7 suction-enhanced, 8 and supernatant decanting methods. 9 As pointed out in Ref.…”

Displacement Pumping of Liquids Radially Inward on Centrifugal Microfluidic Platforms in Motion

“…There is need for the development of passive pumping methods that do not require moving parts, as these are difficult to integrate on disk and can be complex to fabricate [5]. Both Gorkin [6] and a patent by Lee [7] demonstrate the ability to move liquid from the outer edge of the disk back towards the center in order to overcome this limitation. Gorkin used on-disk generated compressed air to prime a siphon whereas Lee stopped the disk and connected it to an external pump.…”

Phase-selective graphene oxide membranes for advanced microfluidic flow control

“…Centrifugal microfluidics offers the benefit that the force field can be accurately controlled over several orders of magnitude by a spindle motor 1 . Such 'Lab-on-aDisc' (LoaD) platforms have emerged as a highly useful tool in biomedical diagnostics because many of the necessary laboratory unit operations (LUOs) in bioanalysis, such as pumping 2 , plasma extraction 3 , mixing 4 , and metering 5 , can be fully automated and implemented. Liquid-handling steps can then be controlled by running a designated spin-frequency protocol to modulate interactions between on-disc liquids and microstructures 1 .…”