Theoretical development and critical analysis of burst frequency equations for passive valves on centrifugal microfluidic platforms

A technique known as thermo-pneumatic (TP) pumping is used to pump fluids on a microfluidic compact disc (CD) back towards the CD center against the centrifugal force that pushes liquids from the center to the perimeter of the disc. Trapped air expands in a TP air chamber during heating, and this creates positive pressure on liquids located in chambers connected to that chamber. While the TP air chamber and connecting channels are easy to fabricate in a one-level CD manufacturing technique, this approach provides only one way pumping between two chambers, is real-estate hungry and leads to unnecessary heating of liquids in close proximity to the TP chamber. In this paper, we present a novel TP push and pull pumping method which allows for pumping of liquid in any direction between two connected liquid chambers. To ensure that implementation of TP push and pull pumping also addresses the issue of space and heating challenges, a multi-level 3D CD design is developed, and localized forced convection heating, rather than infra-red (IR) is applied. On a multi-level 3D CD, the TP features are placed on a top level separate from the rest of the microfluidic processes that are implemented on a lower separate level. This approach allows for heat shielding of the microfluidic process levels, and efficient usage of space on the CD for centrifugal handling of liquids. The use of localized forced convection heating, rather than infra-red (IR) or laser heating in earlier implementations allows not only for TP pumping of liquids while the CD is spinning but also makes heat insulation for TP pumping and other fluidic functions easier. To aid in future implementations of TP push and pull pumping on a multi-level 3D CD, study on CD surface heating is also presented. In this contribution, we also demonstrate an advanced application of pull pumping through the implementation of valve-less switch pumping.

show abstract

“…The CD fabrication technique is similar to that used for single-level CDs in our previous work 14 . Fig.…”

Section: Methodsmentioning

confidence: 99%

Push pull microfluidics on a multi-level 3D CD

et al. 2013

Self Cite

View full text Add to dashboard Cite

show abstract

“…Through varying the rotationally induced fields relative to the statically defined forces such as interfacial or membrane tension, the force equilibrium at a fluid element can be unbalanced. Such static forces can be implemented by capillary action [17][18][19][20][21], dissolvable films (DFs) [22][23], burstable foils [24], elastomeric membranes [25], dead-end pneumatic chambers [26], siphons [27]-29], and pneumatically enhanced centrifugo-pneumatic siphons (CPSVs) [30][31][32][33].…”

Section: Digital Flow Control Schemesmentioning

confidence: 99%

Lumped-Element Modeling for Rapid Design and Simulation of Digital Centrifugal Microfluidic Systems

Mohammadi¹,

Kinahan²,

Ducrée³

2016

Lab-on-a-Chip Fabrication and Application

View full text Add to dashboard Cite

Since the 1990s, centrifugal microfluidic platforms have evolved into a mature technology for the automation of bioanalytical assays in decentralized settings. These "Lab-ona-Disc" (LoaD) systems have already implemented a range of laboratory unit operations (LUOs) such as sample loading, liquid transport, metering, aliquoting, routing, mixing, and washing. By assembling these LUOs in highly functional microfluidic networks, including sample preparation and detection, a sizable portfolio of common test formats such as general chemistry, immunoassays/ protein analysis, nucleic acid testing, and cell counting has been established. The availability of these bioanalytical assay types enables a broad range of applications in fields such as life-science research, biomedical point-ofcare testing and veterinary diagnostics, as well as agrifood, environmental, infrastructural, and industrial monitoring.Recently, a new method of the so-called "event-triggered" flow control has been developed which is independent of the spin rate. These valves, which function in a handshake mode as opposed to the typically batchwise liquid transfers on the "Lab-on-a-Disc" (LoaD) platform, assume a similarly pivotal role as relays and transistors in digital electronics, allowing conditional, logical (flow) control elements. This chapter will describe the modeling of this new generation of "digital" centrifugal microfluidic systems with lowdimensional, lumped-element simulations which have already been instrumental to the modern success story of modern microelectronics.

show abstract

“…This type of valve is based on unbalancing the hydrostatic equilibrium between rotationally induced hydrostatic pressure and the other forces acting on liquid elements such as pneumatic (counter) pressure or capillary force; thus, the key advantage is that the only control input required is modulating the spin-rate of the system innate spindle motor. The high-pass version of this valving type yields upon exceeding a certain rotational frequency; these include capillary burst valves (Chen et al, 2008;Moore et al, 2011;Thio et al, 2013;Li et al, 2010;Haeberle et al, 2006), centrifugo-pneumatic dissolvable film valves (Gorkin III et al, 2012;Nwankire et al, 2014Nwankire et al, , 2015Mishra et al, 2015), burstable foils (van Oordt et al, 2013), elastomeric membranes (Hwang et al, 2011) and deadend pneumatic chambers (Mark et al, 2011). On the other hand, low-pass valves open upon a reduction of the rotational frequency.…”

Section: Introductionmentioning

confidence: 99%

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

Delgado

Kinahan

Julius

et al. 2018

Biosensors and Bioelectronics

View full text Add to dashboard Cite

In this paper we present a wirelessly powered array of 128 centrifugo-pneumatic valves that can be thermally actuated on demand during spinning. The valves can either be triggered by a predefined protocol, wireless signal transmission via Bluetooth, or in response to a sensor monitoring a parameter like the temperature, or homogeneity of the dispersion. Upon activation of a resistive heater, a low-melting membrane (Parafilm™) is removed to vent an entrapped gas pocket, thus letting the incoming liquid wet an intermediate dissolvable film and thereby open the valve. The proposed system allows up to 12 heaters to be activated in parallel, with a response time below 3 s, potentially resulting in 128 actuated valves in under 30 s. We demonstrate, with three examples of common and standard procedures, how the proposed technology could become a powerful tool for implementing diagnostic assays on Lab-on-a-Disc. First, we implement wireless actuation of 64 valves during rotation in a freely programmable sequence, or upon user input in real time. Then, we show a closed-loop centrifugal flow control sequence for which the state of mixing of reagents, evaluated from stroboscopically recorded images, triggers the opening of the valves. In our last experiment, valving and closed-loop control are used to facilitate centrifugal processing of whole blood.

show abstract

Theoretical development and critical analysis of burst frequency equations for passive valves on centrifugal microfluidic platforms

Cited by 49 publications

References 31 publications

Push pull microfluidics on a multi-level 3D CD

Push pull microfluidics on a multi-level 3D CD

Lumped-Element Modeling for Rapid Design and Simulation of Digital Centrifugal Microfluidic Systems

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

Contact Info

Product

Resources

About