Baking Powder Actuated Centrifugo-Pneumatic Valving for Automation of Multi-Step Bioassays

Abstract

We report a new flow control method for centrifugal microfluidic systems; CO2 is released from on-board stored baking powder upon contact with an ancillary liquid. The elevated pressure generated drives the sample into a dead-end pneumatic chamber sealed by a dissolvable film (DF). This liquid incursion wets and dissolves the DF, thus opening the valve. The activation pressure of the DF valve can be tuned by the geometry of the channel upstream of the DF membrane. Through pneumatic coupling with properly dimensioned disc architecture, we established serial cascading of valves, even at a constant spin rate. Similarly, we demonstrate sequential actuation of valves by dividing the disc into a number of distinct pneumatic chambers (separated by DF membranes). Opening these DFs, typically through arrival of a liquid to that location on a disc, permits pressurization of these chambers. This barrier-based scheme provides robust and strictly ordered valve actuation, which is demonstrated by the automation of a multi-step/multi-reagent DNA-based hybridization assay.

Wirelessly powered and remotely controlled valve-array for highly multiplexed analytical assay automation on a centrifugal microfluidic platform

“…These flow control elements include conventional (hydrophilic) siphons (Siegrist et al, 2010;Kitsara et al, 2014) and pneumatically enhanced centrifugo-pneumatic siphon valves (Gorkin III et al, 2010;Godino et al, 2013;Schwemmer et al, 2015). Recently, Kinahan et al (2014aKinahan et al ( , 2015Kinahan et al ( , 2016c introduced event-triggered valves, whereby liquid arriving at strategically chosen points on the disc dissolves a film and, by venting an interconnected pneumatic chamber, triggers the release of liquid from a distal reservoir. For further details on these valving technologies, the reader can refer to the cited literature.…”

“…Full integration of active valving on-disc requires not only the valving method but the inclusion of a wirelessly powered system (Zhu et al, 2017;Loo et al, 2017;Torres Delgado et al, 2016a;Höfflin et al, 2015;Torres Delgado et al, 2016b). Therefore, we combine the previously introduced 'electrified Labon-a-Disc' (eLoaD) platform (Torres Delgado et al, 2016a,b) with the dissolvable film valves introduced in (Kinahan et al, 2014a(Kinahan et al, , 2015(Kinahan et al, , 2016c and an array of resistive heaters to produce a platform which can actuate up to 128 valves in a time and rotation speed -independent sequence. The platform can be controlled using two methods.…”

Multidisciplinary Role of Microfluidics for Biomedical and Diagnostic Applications: Biomedical Microfluidic Devices

“…This special issue of Micromachines entitled ‘Biomedical Microfluidic Devices’ provides a discussion of the technical challenges associated with developing microfluidic devices for biomedical and diagnostic applications. Addressing these challenges requires technological advances in many areas, including sensors [ 1 , 2 ], actuators [ 3 ], materials [ 4 , 5 ], microfabrication techniques [ 6 ], simulations and models [ 7 , 8 , 9 ], and platform technologies [ 10 , 11 , 12 ]. This special issue consists of 12 high-quality papers, including two insightful review articles [ 4 , 12 ].…”

“…Actuators : Successful commercialization of LOC/POC devices has been hindered owing to the lack of reliable microfluidic actuators, such as microvalves and micropumps. To overcome this challenge, Kinahan et al [ 3 ] present a chemically actuated valving mechanism through gas release from baking powder that is initially dry-stored on a centrifugally driven biomedical microfluidic device.…”

“…For example, Tsai’s group [ 10 , 11 ] developed a pressure-driven microfluidic constriction platform to evaluate on-chip red blood cell deformability. In general, according to a distinct set of fluidic manipulation processes, biomedical microfluidic devices can be categorized into different microfluidic platforms, for example, capillary-driven, pressure-driven [ 7 , 8 , 9 , 10 , 11 ], vacuum-driven, electrowetting-driven, centrifugal-driven [ 3 ], droplet-based [ 4 ], and paper-based microfluidic platforms, among others. An article by Basha et al [ 12 ] provides a comprehensive review of the core processes implemented in POC devices (e.g., lysis techniques, nucleic acid extraction, amplification of specific DNA/RNA, and genomic identification methods) and microfluidic platforms suitable for molecular diagnosis (e.g., paper-based, centrifugal-based, and electrowetting-based microfluidic platforms).…”