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A microfluidic control board for high-pressure flow, composition, and relative permittivity
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.ORCID-id: 0000-0002-3966-0220
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.ORCID-id: 0000-0003-2744-1634
2018 (Engelska)Ingår i: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 90, nr 21, s. 12601-12608Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Flow control is central to microfluidics and chromatography. With decreasing dimensions and high pressures, precise fluid flows are often needed. In this paper, a high-pressure flow control system is presented, allowing for the miniaturization of chromatographic systems and the increased performance of microfluidic setups by controlling flow, composition and relative permittivity of two-component flows with CO2. The system consists of four chips: two flow actuator chips, one mixing chip and one relative permittivity sensor. The actuator chips, throttling the flow, required no moving parts as they instead relied on internal heaters to change the fluid resistance. This allows for flow control using miniaturized fluid delivery systems containing only a single pump or pressure source. Mobile phase gradients between 49% to 74% methanol in CO2 were demonstrated. Depending on how the actuator chips were dimensioned, the position of this range could be set for different method-specific needs. With the microfluidic control board, both flow and composition could be controlled from constant pressure sources, drift could be removed, and variations in composition could be lowered by 84%, resulting in microflows of CO2 and methanol with a variation in the composition of 0.30%.

Ort, förlag, år, upplaga, sidor
2018. Vol. 90, nr 21, s. 12601-12608
Nationell ämneskategori
Kemiteknik
Identifikatorer
URN: urn:nbn:se:uu:diva-353953DOI: 10.1021/acs.analchem.8b02758ISI: 000449722500039PubMedID: 30269500OAI: oai:DiVA.org:uu-353953DiVA, id: diva2:1221023
Forskningsfinansiär
Knut och Alice Wallenbergs StiftelseTillgänglig från: 2018-06-19 Skapad: 2018-06-19 Senast uppdaterad: 2018-12-21Bibliografiskt granskad
Ingår i avhandling
1. Microfluidics at High Pressures: Understanding, Sensing, and Control
Öppna denna publikation i ny flik eller fönster >>Microfluidics at High Pressures: Understanding, Sensing, and Control
2018 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

This thesis explores understanding, sensing, and control in high-pressure microfluidics. The high-pressure regime allows fluids to be forced through narrow channels at substantial speed and creates conditions for fluids of high density and low viscosity—features desired in flow-based chemical analyses. With changes to pressure and temperature, fluid properties vary, and for miniaturized flow systems, sensing and control are needed.

For miniaturized chemical analytics to utilize high-pressure fluids, like supercritical CO2, sensors are required for flow characterization. In this thesis, high-pressure tolerant sensors in glass chips have been developed and investigated. By the use of chip-integrated temperature, flow, and relative permittivity sensors, the variable behavior of supercritical CO2 or binary component CO2-alcohol mixtures have been investigated. To be able to change flow rates, a heat-based actuator chip has been developed. By a flow control system, which combines a relative permittivity sensor and heat actuated flow regulators on a modular system, the composition of binary component CO2-alcohol mixtures can be tuned and controlled with feedback.

Flows of multiphase CO2-H2O hold promise for miniaturized extraction systems. In this thesis, parallel multiphase CO2-H2O flow has been studied. To achieve control, methods have been investigated where channels have been modified by the introduction of a guiding ridge and altered by a chemical coating. Flow is a dynamic process, where pressure and temperature can vary with time and place. As the properties of fluids containing CO2 may change with pressure and temperature, properties will also change with time and place. Because of this, instruments with spatial and temporal resolution are needed to better understand dynamic chemical effects at flow. In this thesis, a tool is presented to study the dynamic acidification of aqueous solutions that come in contact with flowing CO2.

By a study performed to understand the strength and pressure tolerance of glass chips, it has been found that the fracture is not only determined by the applied pressure, but also on time and environment.

Ort, förlag, år, upplaga, sidor
Uppsala: Acta Universitatis Upsaliensis, 2018. s. 60
Serie
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1687
Nyckelord
High-pressure microfluidics, supercritical CO2, compressible flow, relative permittivity, integrated electrodes
Nationell ämneskategori
Kemiteknik Materialteknik
Forskningsämne
Teknisk fysik med inriktning mot mikrosystemteknik
Identifikatorer
urn:nbn:se:uu:diva-353964 (URN)978-91-513-0372-7 (ISBN)
Disputation
2018-09-14, Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:00 (Engelska)
Opponent
Handledare
Tillgänglig från: 2018-08-21 Skapad: 2018-06-19 Senast uppdaterad: 2018-08-27

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