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Andersson, M., Wilson, A., Hjort, K. & Klintberg, L. (2019). A microfluidic relative permittivity sensor for feedback control of carbon dioxide expanded liquid flows. Sensors and Actuators A-Physical, 285, 165-172
Open this publication in new window or tab >>A microfluidic relative permittivity sensor for feedback control of carbon dioxide expanded liquid flows
2019 (English)In: Sensors and Actuators A-Physical, ISSN 0924-4247, E-ISSN 1873-3069, Vol. 285, p. 165-172Article in journal (Refereed) Published
Abstract [en]

Binary CO2-alcohol mixtures, such as CO2-expanded liquids (CXLs), are promising green solvents for reaching higher performance in flow chemistry and separation processing. However, their compressibility and high working pressure makes handling challenging. These mixtures allow for a tuneable polarity but, to do so, requires precise flow control. Here, a high-pressure tolerant microfluidic system containing a relative permittivity sensor and a mixing chip is used to actively regulate the relative permittivity of these fluids and indirectly—composition. The sensor is a fluid-filled plate capacitor created using embedded 3D-structured thin films and has a linearity of 0.9999, a sensitivity of 4.88 pF per unit of relative permittivity, and a precision within 0.6% for a sampling volume of 0.3 μL. Composition and relative permittivity of CO2-ethanol mixtures were measured at 82 bar and 21 °C during flow. By flow and dielectric models, this relationship was found to be described by the pure components and a quadratic mixing rule with an interaction parameter, kij, of -0.63 ± 0.02. Microflows with a relative permittivity of 1.7–21.4 were generated, and using the models, this was found to correspond to compositions of 6–90 mol % ethanol in CO2. With the sensor, a closed loop control system was realised and CO2-ethanol flows were tuned to setpoints of the relative permittivity in 30 s.

Keywords
Relative permittivity, Process control, CO2-expanded liquids, Binary fluid mixtures, High-pressure microfluidics
National Category
Chemical Engineering Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-353945 (URN)10.1016/j.sna.2018.11.015 (DOI)000456902600021 ()
Funder
Knut and Alice Wallenberg Foundation
Available from: 2018-06-19 Created: 2018-06-19 Last updated: 2019-02-25Bibliographically approved
Sturesson, P., Seton, R., Klintberg, L., Thornell, G. & Persson, A. (2019). Effect of Resistive and Plasma Heating on the Specific Impulse of a Ceramic Cold Gas Thruster. Journal of microelectromechanical systems, 28(2), 235-244
Open this publication in new window or tab >>Effect of Resistive and Plasma Heating on the Specific Impulse of a Ceramic Cold Gas Thruster
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2019 (English)In: Journal of microelectromechanical systems, ISSN 1057-7157, E-ISSN 1941-0158, Vol. 28, no 2, p. 235-244Article in journal (Refereed) Published
Abstract [en]

The research and development of small satellites has continued to expand over the last decades. However, the propulsion systems with adequate performance have persisted to be a great challenge. In this paper, the effects of three different heaters on the specific impulse and overall thrust efficiency of a cold gas microthruster are presented. They consisted of a conventional, printed resistive thick-film element, a freely suspended wire, and a stripline split-ring resonator microplasma source, and were integrated in a single device made from the high-temperature co-fired ceramics. The devices were evaluated in two setups, where the first measured thrust and the other measured shock cell geometry. In addition, the resistive elements were evaluated as gas temperature sensors. The microplasma source was found to provide the greatest improvement in both specific impulse and thrust efficiency, increasing the former from an un-heated level of 44–56 s when heating with a power of 1.1 W. This corresponded to a thrust efficiency of 55%, which could be compared with the results from the wire and printed heaters which were 51s and 18%, and 45s and 14%, respectively. The combined results also showed that imaging the shock cells of a plasma heated thruster was a simple and effective way to determine its performance, when compared to the traditional thrust balance method.

Keywords
Microthruster, HTCC, Resistive Heating, Plasma Heating, Specific Impulse, Shock Cells
National Category
Aerospace Engineering
Research subject
Engineering Science with specialization in Microsystems Technology
Identifiers
urn:nbn:se:uu:diva-356675 (URN)10.1109/JMEMS.2019.2893359 (DOI)000463623600008 ()
Available from: 2018-08-02 Created: 2018-08-02 Last updated: 2019-04-25Bibliographically approved
Werr, G., Khaji, Z., Ohlin, M., Andersson, M., Klintberg, L., Searle, S., . . . Tenje, M. (2019). Integrated thin film resistive sensors for in situ temperature measurements in an acoustic trap. Journal of Micromechanics and Microengineering, 29(9), Article ID 095003.
Open this publication in new window or tab >>Integrated thin film resistive sensors for in situ temperature measurements in an acoustic trap
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2019 (English)In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 29, no 9, article id 095003Article in journal (Refereed) Published
Abstract [en]

This work presents an acoustic trap with integrated thin film sensors to monitor temperature variations during operation. The acoustic trap is wet-etched in glass with a thermally bonded glass lid and the thin-film sensors are integrated during fabrication. We evaluated the performance of the integrated temperature sensors and measured a temperature sensitivity of +/- 0.01 degrees C and confirmed that the read-out of the thin film sensors was not affected neither by the ionic conductivity of the solution nor the addition of microparticles into the acoustic trap. From the experiments we observed a temperature increase of the acoustic trap during operation as a result of the dissipative heating of the the piezoelectric element used to actuate the trap. We also showed that when external convective cooling was applied to the system, the temperature increase of the acoustic trap was higher than the temperature increase of the piezoelectric element itself. This shows the importance of using integrated temperature sensors in acoustic trapping to monitor the local environmental conditions.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2019
Keywords
acoustophoresis, integrated RTD, external TC, acoustic trap, glass chip
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-391278 (URN)10.1088/1361-6439/ab2ac8 (DOI)000476561400001 ()
Funder
Knut and Alice Wallenberg Foundation
Available from: 2019-08-22 Created: 2019-08-22 Last updated: 2019-08-22Bibliographically approved
Werr, G., Khaji, Z., Ohlin, M., Andersson, M., Klintberg, L., Searle, S., . . . Tenje, M. (2019). Integrated thin film resistive sensors for in situ temperature measurements in an acoustic trap. In: Acoustofluidics 2019: This annual meeting will be held in Twente, The Netherlands in 2019. This focused meeting is dedicated to exploring the science, engineering, and use of micro- to nanoscale acoustofluidics.. Paper presented at Acoustofluidics 2019, 25-28 August 2019, Enschede, Netherlands (pp. 140-141).
Open this publication in new window or tab >>Integrated thin film resistive sensors for in situ temperature measurements in an acoustic trap
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2019 (English)In: Acoustofluidics 2019: This annual meeting will be held in Twente, The Netherlands in 2019. This focused meeting is dedicated to exploring the science, engineering, and use of micro- to nanoscale acoustofluidics., 2019, p. 140-141Conference paper, Poster (with or without abstract) (Other academic)
Abstract [en]

This work presents an acoustic trap with integrated thin film sensors to monitor temperature variations during operation. The acoustic trap is wet-etched in glass with a thermally bonded glass lid and the thin-film sensors are integrated during fabrication. We evaluated the performance of the integrated temperature sensors and measured a temperature sensitivity of ±0.01 °C and confirmed that the read-out of the thin film sensors was not affected neither by the ionic conducitiviy of the solution nor the addition of microparticles into the acoustic trap. From the experiments we observed a temperature increase of the acoustic trap during operation as a result of the dissipative heating of the the piezoelectric element used to actuate the trap. We also showed that when external convective cooling was applied to the system, the temperature increase of the acoustic trap was higher than the temperature incresase of the piezoelectric element itself. This shows the importance of using integrated temperature sensors in acoustic trapping to monitor the environmental conditions.

Keywords
acoustophoresis, platinum RTD, external TC, integrated temperature sensor, thin film resistive sensor, acoustic trapping
National Category
Medical Laboratory and Measurements Technologies
Identifiers
urn:nbn:se:uu:diva-398685 (URN)
Conference
Acoustofluidics 2019, 25-28 August 2019, Enschede, Netherlands
Funder
Knut and Alice Wallenberg Foundation
Available from: 2019-12-09 Created: 2019-12-09 Last updated: 2019-12-09Bibliographically approved
Sturesson, P., Klintberg, L. & Thornell, G. (2019). Pirani Microgauge Fabricated of High-Temperature Co-fired Ceramics with Integrated Platinum Wires. Sensors and Actuators A-Physical, 285, 8-16
Open this publication in new window or tab >>Pirani Microgauge Fabricated of High-Temperature Co-fired Ceramics with Integrated Platinum Wires
2019 (English)In: Sensors and Actuators A-Physical, ISSN 0924-4247, E-ISSN 1873-3069, Vol. 285, p. 8-16Article in journal (Refereed) Published
Abstract [en]

This paper presents the integration and pressure sensor operation of platinum bond wires in High-Temperature Co-fired alumina (HTCC). Devices were fabricated with a 50 μm diameter wire suspended across a 500 μm wide cavity in green-body state HTCC, electrically connected to screen printed alumina conductors. The substrate shrinkage during sintering to a cavity width of 400 μm causes the wire element to elevate from the cavity´s bottom surface. Resulting devices were compared with reference devices, containing screen-printed sensor elements, as Pirani gauges operated at 100 °C in constant-resistance mode, and in dynamic mode with a feeding current of 1 A in a pressure range from 10−4 Torr to atmospheric pressure. Also, devices with wire lengths between 500 and 3500 μm were operated and studied in constant-resistance and dynamic mode. Lastly, a device is demonstrated in operation at a mean temperature of 830 °C. The results include wire elements with a consistent elevation from their substrate surfaces, with irregularities along the wires. The wire devices exhibit a faster pressure response in dynamic mode than the reference devices do but operate similarly in constant-resistance mode. Increasing the wire element length shows an increasing dynamic pressure range but a decreasing maximum sensitivity. The sensitivity is retained in high temperature mode, but the dynamic range is extended from about 10 Torr to about 700 Torr.

Keywords
HTCC, Pirani gauge, High temperature, Bond wires
National Category
Ceramics Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Microsystems Technology
Identifiers
urn:nbn:se:uu:diva-356481 (URN)10.1016/j.sna.2018.10.008 (DOI)000456902600002 ()
Available from: 2018-07-30 Created: 2018-07-30 Last updated: 2019-02-19Bibliographically approved
Andersson, M., Svensson, K., Klintberg, L. & Hjort, K. (2018). A microfluidic control board for high-pressure flow, composition, and relative permittivity. Analytical Chemistry, 90(21), 12601-12608
Open this publication in new window or tab >>A microfluidic control board for high-pressure flow, composition, and relative permittivity
2018 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 90, no 21, p. 12601-12608Article in journal (Refereed) 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%.

National Category
Chemical Engineering
Identifiers
urn:nbn:se:uu:diva-353953 (URN)10.1021/acs.analchem.8b02758 (DOI)000449722500039 ()30269500 (PubMedID)
Funder
Knut and Alice Wallenberg Foundation
Available from: 2018-06-19 Created: 2018-06-19 Last updated: 2018-12-21Bibliographically approved
Andersson, M., Rodriguez-Meizoso, I., Turner, C., Hjort, K. & Klintberg, L. (2018). Dynamic pH determination at high pressure of aqueous additive mixtures in contact with dense CO2. Journal of Supercritical Fluids, 136, 95-101
Open this publication in new window or tab >>Dynamic pH determination at high pressure of aqueous additive mixtures in contact with dense CO2
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2018 (English)In: Journal of Supercritical Fluids, ISSN 0896-8446, E-ISSN 1872-8162, Vol. 136, p. 95-101Article in journal (Refereed) Published
Abstract [en]

A system consisting of a high-pressure tolerant microfluidic glass chip, high-speed absorbance imaging, and image processing has been developed to study rapid dynamic events like pH change in a multiphase flow. The system gives both kinetic and quantitative equilibrated information. By tracking the interactions of aqueous additive mixtures and liquid CO2, at 80 bar and 24 °C, under flow, measurement at a given P, T condition is done in 0.25 s. The acidification rate to steady state was found to be mass transport limited, occurring in less than 1 s. For 30 mM of the additives ammonium acetate and ammonium formate, equilibrium pH of 4.5 and 4.1, respectively, was seen. These additives are of key importance in common mobile phases used in SFC.

Keywords
Supercritical fluid chromatography, High-pressure microfluidics, Additive salts, Dense CO, Multiphase flow, Image analysis
National Category
Chemical Engineering Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-353940 (URN)10.1016/j.supflu.2018.02.012 (DOI)000430767400011 ()
Funder
Knut and Alice Wallenberg Foundation
Available from: 2018-06-18 Created: 2018-06-18 Last updated: 2018-08-02Bibliographically approved
Svensson, K., Södergren, S., Andersson, M., Klintberg, L. & Hjort, K. (2018). High-pressure microfluidic electrochemical and image analysis dual detection for HPLC. In: : . Paper presented at Micromechanics and Microsystems Europe Workshop (MME 2018), Aug. 26-29, Smolenice, Slovakia (pp. 113-119).
Open this publication in new window or tab >>High-pressure microfluidic electrochemical and image analysis dual detection for HPLC
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2018 (English)Conference paper, Oral presentation with published abstract (Other academic)
Abstract [en]

High-performance liquid chromatography (HPLC) is often set as the lab-based golden standard. For point-of-care and point-of-site applications, making HPLC portable, easy to use and low cost, is very desirable. To reach lower costs, one important task is the development of suitable detectors. Because of the potential for low cost and high performance, a dual-detection microfluidic chip with an electrochemical detector (ECD) and optical access for image analysis was evaluated at high pressure, downstream an HPLC column. For the image analysis, a camera and near-UV-light was used to extract absorption data. To validate the response, a spectrometer was coupled downstream the chip. The results of the three different detectors were comparable, with the camera providing similar absorbance-time chromatograms as the spectrometer. However, the ECD registered only peaks from one of two analytes. To conclude, this experimental setup has potential to provide better understanding of the capability for microfluidic HPLC systems.

National Category
Engineering and Technology Other Chemical Engineering
Research subject
Engineering Science with specialization in Microsystems Technology
Identifiers
urn:nbn:se:uu:diva-367300 (URN)
Conference
Micromechanics and Microsystems Europe Workshop (MME 2018), Aug. 26-29, Smolenice, Slovakia
Funder
The Kamprad Family Foundation, 20170169
Available from: 2018-11-29 Created: 2018-11-29 Last updated: 2018-12-10Bibliographically approved
Andersson, M., Klintberg, L., Svensson, k., Södergren, S. & Hjort, K. (2018). Microfluidics for High-Pressure Analyses. In: Samilu Fransilla (Ed.), 12th Micronano System Workshop (MSW 2018, May 14-15, 2018, Espoo, Finland): . Paper presented at 12th Micronano System Workshop (MSW 2018, May 14-15, 2018, Espoo, Finland) (pp. 8-8).
Open this publication in new window or tab >>Microfluidics for High-Pressure Analyses
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2018 (English)In: 12th Micronano System Workshop (MSW 2018, May 14-15, 2018, Espoo, Finland) / [ed] Samilu Fransilla, 2018, p. 8-8Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

When using appropriate materials and microfabrication techniques, the small dimensionsand mechanical stability of microstructured devices allow for processes at high pressureswithout loss in safety. The largest area of applications has been demonstrated in chemistry,where extraction, synthesis and analyses often excel at high densities and high temperatures.These two parameters are accessible through high pressures. Capillary chemistry has beenused since long but, just like in low-pressure applications, there are several advantages in usingmicrofluidic platforms for control of reactions, catalysis, mixing and separation. For example,planar isothermal set-ups, large local variations in geometries, dense form factors, small deadvolumes and precisely positioned microstructures.In analytical systems, we are studying high-pressure components and microsystems forsampling, sample preparation, analyses and fractionation. We will present what drives ourresearch and development: Our experimental set-up with high-pressure pumps, high-speedcamera, sensors, valves, piston-chambers, backpressure regulators, cooling table, etc. How wehave built capability in pumping and valving by the use of stainless steel and paraffinactuation. How we are making high pressure silicon-glass and glass-glass chips with integratedelectrical thin film sensors, using printed circuit boards to ease handling of the chips andintegrating modules. A set of relevant publications are listed below.

Keywords
high pressure, microfluidics
National Category
Medical Engineering Engineering and Technology
Research subject
Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-350933 (URN)
Conference
12th Micronano System Workshop (MSW 2018, May 14-15, 2018, Espoo, Finland)
Available from: 2018-05-17 Created: 2018-05-17 Last updated: 2018-10-19Bibliographically approved
Åkerfeldt, E., Klintberg, L., Sturesson, P. & Thornell, G. (2018). Taking ceramic microcomponents to higher temperatures. In: : . Paper presented at Micronano System Workshop (MSW 2018).
Open this publication in new window or tab >>Taking ceramic microcomponents to higher temperatures
2018 (English)Conference paper, Poster (with or without abstract) (Refereed)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-363404 (URN)
Conference
Micronano System Workshop (MSW 2018)
Available from: 2018-10-18 Created: 2018-10-18 Last updated: 2018-10-18
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-7715-3142

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