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Nordin AN, Abd Manaf A. Design and fabrication technologies for microfluidic sensors. MICROFLUIDIC BIOSENSORS 2023:41-85. [DOI: 10.1016/b978-0-12-823846-2.00004-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
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Wilder LM, Thompson JR, Crooks RM. Electrochemical pH regulation in droplet microfluidics. LAB ON A CHIP 2022; 22:632-640. [PMID: 35018955 DOI: 10.1039/d1lc00952d] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
We report a method for electrochemical pH regulation in microdroplets generated in a microfluidic device. The key finding is that controlled quantities of reagents can be generated electrochemically in moving microdroplets confined within a microfluidic channel. Additionally, products generated at the anode and cathode can be isolated within descendant microdroplets. Specifically, ∼5 nL water-in-oil microdroplets are produced at a T-junction and then later split into two descendant droplets. During splitting, floor-patterned microelectrodes drive water electrolysis within the aqueous microdroplets to produce H+ and OH-. This results in a change in the pHs of the descendant droplets. The droplet pH can be regulated over a range of 5.9 to 7.7 by injecting controlled amounts of charge into the droplets. When the injected charge is between -6.3 and 54.5 nC nL-1, the measured pH of the resulting droplets is within ±0.1 pH units of that predicted based on the magnitude of the injected charge. This technique can likely be adapted to electrogeneration of other reagents within microdroplets.
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Affiliation(s)
- Logan M Wilder
- Department of Chemistry and the Texas Materials Institute, The University of Texas at Austin, 105 E. 24th Street, Stop A5300, Austin, Texas 78712-1224, USA.
| | - Jonathan R Thompson
- Department of Chemistry and the Texas Materials Institute, The University of Texas at Austin, 105 E. 24th Street, Stop A5300, Austin, Texas 78712-1224, USA.
| | - Richard M Crooks
- Department of Chemistry and the Texas Materials Institute, The University of Texas at Austin, 105 E. 24th Street, Stop A5300, Austin, Texas 78712-1224, USA.
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Quantitative electrolysis of droplet contents in microfluidic channels. Concept and experimental validation. Electrochim Acta 2021. [DOI: 10.1016/j.electacta.2021.139017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Leroy A, Teixidor J, Bertsch A, Renaud P. In-flow electrochemical detection of chemicals in droplets with pyrolysed photoresist electrodes: application as a module for quantification of microsampled dopamine. LAB ON A CHIP 2021; 21:3328-3337. [PMID: 34250532 DOI: 10.1039/d1lc00116g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The electrochemical quantification of analytes in droplets of PBS separated by a fluorinated phase was investigated. PDMS-fused silica chips with pyrolysed photoresist electrodes were prepared using a simple fabrication technique and used to analyze droplets in flow. Potentiostatic chronoamperometry provided current readouts consistent with mass transport and the concentration inside the droplets. This paper highlights measurements of dopamine in droplets in T-junction microfluidic chips at unprecedently low concentrations, with a limit of detection of 207 nM and a linear range of 0.21-20 μM, giving results similar to continuous flow electrochemistry and allowing the analysis in the striatal extracellular range (<1 μM). The system was applied to the quick and reliable on-line detection of dopamine concentration steps in droplets collected with a microsampling probe in vitro, demonstrating the usefulness of the electrochemical device as a quantification module for microsampled chemicals in droplets.
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Affiliation(s)
- Albert Leroy
- EPFL-STI-IMT-LMIS4, École Polytechnique Fédérale de Lausanne, Station 17, CH-1015 Lausanne, Switzerland.
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Delahaye T, Lombardo T, Sella C, Thouin L. Electrochemical assessments of droplet contents in microfluidic channels. Application to the titration of heterogeneous droplets. Anal Chim Acta 2021; 1155:338344. [PMID: 33766324 DOI: 10.1016/j.aca.2021.338344] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 01/15/2021] [Accepted: 02/17/2021] [Indexed: 01/08/2023]
Abstract
Series of aqueous droplets containing redox species were generated on-demand in a microfluidic channel and detected downstream by an electrochemical cell. Depending on the cell geometry, amperometric detections were performed to simultaneously determine the velocity, volume and content of circulating droplets in oil. Volumes and velocities were estimated from specific transition times on the chronoamperometric responses, while charge were evaluated from current integration. The results showed that the total charge within droplets was controlled by the geometry of the electrochemical cell and droplet velocity, leading to accurate determinations of droplet content under specific operating conditions. An active merging of droplets with titrating solutions was tested for analytical purposes. The results demonstrated that even if the mixing was not complete during detection, the assessment of droplet content was still valid. The performance of electrochemical detection was thus evidenced to determine the content of heterogeneous droplets. This property is pertinent since the design of sophisticated circuits is no longer required to fully homogenize the droplet content before characterization, opening broader perspectives in droplet-based microfluidics.
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Affiliation(s)
- Thomas Delahaye
- PASTEUR, Département de Chimie, Ecole Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005, Paris, France
| | - Teo Lombardo
- PASTEUR, Département de Chimie, Ecole Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005, Paris, France
| | - Catherine Sella
- PASTEUR, Département de Chimie, Ecole Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005, Paris, France
| | - Laurent Thouin
- PASTEUR, Département de Chimie, Ecole Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005, Paris, France.
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Klunder KJ, Clark KM, McCord C, Berg KE, Minteer SD, Henry CS. Polycaprolactone-enabled sealing and carbon composite electrode integration into electrochemical microfluidics. LAB ON A CHIP 2019; 19:2589-2597. [PMID: 31250868 PMCID: PMC6801002 DOI: 10.1039/c9lc00417c] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Combining electrochemistry with microfluidics is attractive for a wide array of applications including multiplexing, automation, and high-throughput screening. Electrochemical instrumentation also has the advantage of being low-cost and can enable high analyte sensitivity. For many electrochemical microfluidic applications, carbon electrodes are more desirable than noble metals because they are resistant to fouling, have high activity, and large electrochemical solvent windows. At present, fabrication of electrochemical microfluidic devices bearing integrated carbon electrodes remains a challenge. Here, a new system for integrating polycaprolactone (PCL) and carbon composite electrodes into microfluidics is presented. The PCL : carbon composites have excellent electrochemical activity towards a wide range of analytes as well as high electrical conductivity (∼1000 S m-1). The new system utilizes a laser cutter for fast, simple fabrication of microfluidics using PCL as a bonding layer. As a proof-of-concept application, oil-in-water and water-in-oil droplets are electrochemically analysed. Small-scale electrochemical organic synthesis for TEMPO mediated alcohol oxidation is also demonstrated.
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Affiliation(s)
- Kevin J Klunder
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA. and Department of Chemistry, University of Utah, Salt Lake City, UT 84112, USA
| | - Kaylee M Clark
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA.
| | - Cynthia McCord
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA.
| | - Kathleen E Berg
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA.
| | - Shelley D Minteer
- Department of Chemistry, University of Utah, Salt Lake City, UT 84112, USA
| | - Charles S Henry
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA.
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Lombardo T, Lancellotti L, Souprayen C, Sella C, Thouin L. Electrochemical Detection of Droplets in Microfluidic Devices: Simultaneous Determination of Velocity, Size and Content. ELECTROANAL 2019. [DOI: 10.1002/elan.201900293] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Teo Lombardo
- Département de chimie, Ecole normale supérieureUniversité PSL, Sorbonne Université, CNRS 75005 Paris France
| | - Lidia Lancellotti
- Département de chimie, Ecole normale supérieureUniversité PSL, Sorbonne Université, CNRS 75005 Paris France
| | - Christelle Souprayen
- Département de chimie, Ecole normale supérieureUniversité PSL, Sorbonne Université, CNRS 75005 Paris France
| | - Catherine Sella
- Département de chimie, Ecole normale supérieureUniversité PSL, Sorbonne Université, CNRS 75005 Paris France
| | - Laurent Thouin
- Département de chimie, Ecole normale supérieureUniversité PSL, Sorbonne Université, CNRS 75005 Paris France
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Abstract
Single-cell analysis serves as an important approach to study cell functions and interactions. Catering to the demand of Big Data Era, fast reactions for single cells and paralleled high-throughput analysis have become an urgent need. Microdroplet in microfluidics has advantages of modularity and integrity, as well as high throughput and sensitivity, which present great potential in the field of single-cell analysis. This review is carried out on three aspects to introduce microdroplet chips for single-cell analysis: droplet formation, droplet detection and practical functions. Structures of droplet formation are categorized into three types, including T-shaped channel, flow-involved channel and three-dimensional micro-vortice. The detection methods, including fluorescence, Raman spectroscopy, mass spectroscopy and electrochemical detection, are summarized from applications. Both pros and cons for existing techniques are reviewed and discussed. The functions of microdroplets-on-chip cover cell culture, nucleic acid test and cell identification. For each field, principles/mechanisms and/or schematic images are laconically introduced. Microdroplet in microfluidics has become a major research direction in single-cell analysis. With updated methods of droplet formation such as inertial ordering and micro-vortice, microdroplets-based biochips will expect high throughput detection and high-accuracy trace detection for clinical diagnosis in the near future.
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Affiliation(s)
- Aihui Wang
- 1 Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China.,2 State Key Laboratory of Oncogenes and Related Genes, Institute for Personalized Medicine, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China.,3 School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Aynur Abdulla
- 1 Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China.,2 State Key Laboratory of Oncogenes and Related Genes, Institute for Personalized Medicine, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Xianting Ding
- 1 Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China.,2 State Key Laboratory of Oncogenes and Related Genes, Institute for Personalized Medicine, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
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