Development of a Microfluidic Unit for Sequencing Fluid Samples for Composition Analysis

Abstract

ReuseUnless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. A microfluidic sample-sequencing unit was developed as a part of a high-throughput catalyst screening facility. It may find applications wherever a fluid is to be selected for analysis from any one of several sources, such as microreactors operating in parallel. The novel feature is that the key components are fluidic valves having no moving parts and operating at very low sample flow Reynolds numbers, typically below 100. The inertial effects utilized in conventional no-moving-part fluidics are nearly absent; instead, the flows are pressure-driven. Switching between input channels is by high-Reynolds-number control flows, the jet pumping effect of which simultaneously cleans the downstream cavities to prevent crosscontamination between the samples. In the configuration discussed here, the integrated circuit containing an array of 16 valves is etched into an 84 mm diameter stainless steel foil. This is clamped into a massive assembly containing 16 mini-reactors operated at up to 400 C and 4 MPa. This paper describes the design basis and experience with prototypes. Results of CFD analysis, with scrutiny of some discrepancies when compared with flow visualization, is included. 0263-8762/04/$30.00+0.00 # 2004 Institution of Chemical Engineers www.ingentaselect.com=titles=02638762.htm Trans IChemE, Part A, June 2004 Chemical Engineering

Process Intensification by Miniaturization

“…Indeed, using microreactors for HTS of fluid-liquid molecular catalysis offers considerable advantages over traditional parallel batch operations by ensuring good heat and mass transport in a small volume, reducing sample quantities (to lg levels), providing a large range of operating conditions (temperature, pressure), fewer, simpler electro-mechanical moving parts and throughput testing frequencies of more than five hundred per day. Further data concerning a part of the high throughput catalyst screening facility are presented in [12], where a microfluidic unit for sequencing fluid samples for composition analysis was developed. The novel feature is the use of an array of micro-fluidic valves having no moving parts and operating at very low sample flow Reynolds numbers, typically below 100.…”

Subdynamic asymptotic behavior of microfluidic valves

“…12. An array of these valves forms the basic part of the sampling unit [10] for selecting a sample from several microreactors to be delivered into an analyzer [14]. The special features are due to the requirements: 1) to propel all of the control flow to V despite the adverse pressure drop from V to Y, 2) to reverse the flow at Y by entraining a small purge flow to clear previous sample remnant from stagnant zones in the flow path to the analyzer, and 3) to decouple S from the effects of control flow so that it is influenced only by the ideally constant pressure at V (not the dynamic pressure of the control flow).…”

“…To facilitate the effect, the valve part between the control inlet and the vent is shaped as a classical jet pump (with one-sided suction port-note the similarity of this part and the valve which at high Re is also a jet pump, but with suction ports on both sides). The properties were investigated, as presented in [14], by three coordinated approaches. Apart from experimental measurements of the characteristics, the internal flowfield was studied using flow visualization in a scaled-up laboratory model as well as by the usual steady-state numerical CFD solutions.…”

“…The governing equations certainly do not suggest any physical reason for such an essential change in the character of the flow. Yet the regime is there and the transition into it is quite abrupt and well defined, especially in cases with the local minima as and jet pumping effect in the CLOSED state [14].…”

“…18. In an unloaded valve, the total supplied flow is divided into (12) while the output flow rate is (13) so that their ratio (1) depends only on the ratio (14) of the corresponding parameters (related to the same reference value B) (15) In the case of the valve , the ratio of the asymptotic values of the pressure parameters is (16) so that the asymptotic value of the relative output flow in the subdynamic domain should be (17) This is in excellent agreement with the numerical flowfield computation results for zero driving pressure in Fig. 7.…”