Serial siphon valving for centrifugal microfluidic platforms

Abstract

Today, the focus in microfluidic platforms for diagnostics is on the integration of several analysis steps toward sample-to-answer systems. One of the main challenges to integration is the requirement for serial valving to allow the sequential release of fluids in a temporally and spatially controlled manner. The advantages offered by centrifugal microfluidic platforms make them excellent candidates for integration of biological analysis steps, yet they are limited by the lack of robust serial valving technologies. This is especially true for the majority of centrifugal microfluidic devices that rely on hydrophilic surfaces, where few passive serial valving techniques function reliably. Building on the useful functionality of centrifugal microfluidic siphoning previously shown, a novel serial siphon valve is introduced that relies on multiple, inline siphons to provide for a better controlled, sequential release of fluids. The introduction of this novel concept is followed by an analytical analysis of the device.Proof-of-concept is also demonstrated, and examples are provided to illustrate the range of functionality of the serial siphon valve. The serial siphon is shown to be robust and reproducible, with variability caused by the dependence on contact angle, rotation velocity, and fluidic properties (viz., surface tension) significantly reduced compared to current microfluidic, centrifugal serial valving technologies.

Integrating electrochemical detection with centrifugal microfluidics for real-time and fully automated sample testing

“…For instance, the platform could be used to measure under continuous mixing, 32,33 during intermediate steps of syphon valving, 34 or for electrochemical titration measurements.…”

Lab-on-a-CD: A Fully Integrated Molecular Diagnostic System

“…Kitsara et al spun coat polyvinyl alcohol (PVA) and (hydroxypropyl) methyl cellulose (HPMC) on PMMA surfaces, demonstrating a contact angle change from 68° to 22° and 27°, respectively, that lasted for more than 60 days. This surface treatment was tested on a CD device with serial siphon valves, which was previously designed by Siegrist et al, 10 and a sandwich immunoassay was implemented to validate the biocompatibility of the treatment. 22 …”

Experimental validation of numerical study on thermoelectric-based heating in an integrated centrifugal microfluidic platform for polymerase chain reaction amplification

“…[14][15][16] However, the handling of liquid/vapor PCR samples in microfluidic devices is not a simple task when confronted with the high temperatures and pressures created within the PCR chamber region. [17][18][19][20][21][22][23] Thermoelectric-based ice-valves are an ideal valving method for a stationary integrated centrifugal microfluidic system. 24 These ice-valves are vapor-tight and strong enough to withstand the high temperatures and pressures within the PCR chamber.…”