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Paquet-Mercier F, Parvinzadeh Gashti M, Bellavance J, Taghavi SM, Greener J. Through thick and thin: a microfluidic approach for continuous measurements of biofilm viscosity and the effect of ionic strength. LAB ON A CHIP 2016; 16:4710-4717. [PMID: 27808313 DOI: 10.1039/c6lc01101b] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Continuous, non-intrusive measurements of time-varying viscosity of Pseudomonas sp. biofilms are made using a microfluidic method that combines video tracking with a semi-empirical viscous flow model. The approach uses measured velocity and height of tracked biofilm segments, which move under the constant laminar flow of a nutrient solution. Following a low viscosity growth stage, rapid thickening was observed. During this stage, viscosity increased by over an order of magnitude in less than ten hours. The technique was also demonstrated as a promising platform for parallel experiments by subjecting multiple biofilm-laden microchannels to nutrient solutions containing NaCl in the range of 0 to 34 mM. Preliminary data suggest a strong relationship between ionic strength and biofilm properties, such as average viscosity and rapid thickening onset time. The technique opens the way for a combinatorial approach to study the response of biofilm viscosity under well-controlled physical, chemical and biological growth conditions.
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Greener J, Parvinzadeh Gashti M, Eslami A, Zarabadi MP, Taghavi SM. A microfluidic method and custom model for continuous, non-intrusive biofilm viscosity measurements under different nutrient conditions. BIOMICROFLUIDICS 2016; 10:064107. [PMID: 27965730 PMCID: PMC5116028 DOI: 10.1063/1.4968522] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Accepted: 11/09/2016] [Indexed: 05/24/2023]
Abstract
Straight, low-aspect ratio micro flow cells are used to support biofilm attachment and preferential accumulation at the short side-wall, which progressively reduces the effective channel width. The biofilm shifts downstream at measurable velocities under the imposed force from the constant laminar co-flowing nutrient stream. The dynamic behaviour of the biofilm viscosity is modeled semi-analytically, based on experimental measurements of biofilm dimensions and velocity as inputs. The technique advances the study of biofilm mechanical properties by strongly limiting biases related to non-Newtonian biofilm properties (e.g., shear dependent viscosity) with excellent time resolution. To demonstrate the proof of principle, young Pseudomonas sp. biofilms were analyzed under different nutrient concentrations and constant micro-flow conditions. The striking results show that large initial differences in biofilm viscosities grown under different nutrient concentrations become nearly identical in less than one day, followed by a continuous thickening process. The technique verifies that in 50 h from inoculation to early maturation stages, biofilm viscosity could grow by over 2 orders of magnitude. The approach opens the way for detailed studies of mechanical properties under a wide variety of physiochemical conditions, such as ionic strength, temperature, and shear stress.
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Asselin J, Parvinzadeh Gashti M, Boudreau D, Greener J. A Microfluidic Platform with Nanoparticle-Based Metal-Enhanced Fluorescence for pH Mapping Acidified Aqueous Solutions by CO2 Microbubbles. ACTA ACUST UNITED AC 2016. [DOI: 10.1557/adv.2016.288] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Gashti MP, Asselin J, Barbeau J, Boudreau D, Greener J. A microfluidic platform with pH imaging for chemical and hydrodynamic stimulation of intact oral biofilms. LAB ON A CHIP 2016; 16:1412-9. [PMID: 26956837 DOI: 10.1039/c5lc01540e] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A microfluidic platform with a fluorescent nanoparticle-based sensor is demonstrated for real-time, ratiometric pH imaging of biofilms. Sensing is accomplished by a thin patterned layer of covalently bonded Ag@SiO2+FiTC nanoparticles on an embedded planar glass substrate. The system is designed to be sensitive, responsive and give sufficient spatial resolution to enable new micro-scale studies of the dynamic response of oral biofilms to well-controlled chemical and hydrodynamic stimulation. Performance under challenging operational conditions is demonstrated, which include long-duration exposure to sheer stresses, photoexcitation and pH sensor biofouling. After comprehensive validation, the device was used to monitor pH changes at the attachment surface of a biofilm of the oral bacteria, Streptococcus salivarius. By controlling flow and chemical concentration conditions in the microchannel, biochemical and mass transport contributions to the Stephan curve could be probed individually. This opens the way for the analysis of separate contributions to dental caries due to localized acidification directly at the biofilm tooth interface.
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Kara A, Reitz A, Mathault J, Mehou-Loko S, Amirdehi MA, Miled A, Greener J. Electrochemical imaging for microfluidics: a full-system approach. LAB ON A CHIP 2016; 16:1081-1087. [PMID: 26912254 DOI: 10.1039/c6lc00077k] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Electrochemistry is developed as a new chemical imaging modality for microfluidics. The technique is based on multipoint voltammetry using an embedded 20 × 10 miniature electrode array implemented on a customized printed circuit board. Electrode durability was enhanced by chemical modification of the electrode surfaces, which enabled continuous, stable use for over 2 months. A system-level approach enables automatic calibration, data acquisition and data processing through a graphical user interface. Following data processing, redox currents and peak positions are extracted from location-specific voltammograms and converted into pixels of an "electrochemical image". The system is validated by imaging steady-state and dynamic laminar flow patterns of flow-confined solutions of the redox pairs Fe(CN)6(3-/4-) or multi-redox environments that include coflowing Ru(NH3)6(2+/3+) solutions. The images obtained are compared with flow simulations and optical images for validation. A strategy to achieve measurements with spatial resolution smaller than the individual electrodes is also demonstrated as an avenue to enhance image spatial resolution. It is expected that this new approach to chemical imaging will expand the applicability of microfluidics in certain areas of chemistry and biology without requiring expertise in electrochemistry.
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Mathault J, Zamprogno P, Greener J, Miled A. Microfluidic platform for neurotransmitter sensing based on cyclic voltammetry and dielectrophoresis for in vitro experiments. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2016; 2015:2171-4. [PMID: 26736720 DOI: 10.1109/embc.2015.7318820] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This paper presents a new microfluidic platform that can simultaneously measure and locally modulate neurotransmitter concentration in a neuron network. This work focuses on the development of a first prototype including a potentiostat and electrode functionalization to detect several neurotransmitter's simultaneously. We tested dopamine as proof of concept to validate functionality. The system is based on 320 bidirectional electrode array for dielectrophoretic manipulation and cyclic voltammetry. Each electrode is connected to a mechanical multiplexer in order to reduce noise interference and fully isolate the electrode. The multiplexing rate is 476 kHz and each electrode can drive a signal with an amplitude of 60 V pp for dielectrophoretic manipulation.
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Parvinzadeh Gashti M, Bellavance J, Kroukamp O, Wolfaardt G, Taghavi SM, Greener J. Live-streaming: Time-lapse video evidence of novel streamer formation mechanism and varying viscosity. BIOMICROFLUIDICS 2015; 9:041101. [PMID: 26339304 PMCID: PMC4529438 DOI: 10.1063/1.4928296] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2015] [Accepted: 07/29/2015] [Indexed: 05/12/2023]
Abstract
Time-lapse videos of growing biofilms were analyzed using a background subtraction method, which removed camouflaging effects from the heterogeneous field of view to reveal evidence of streamer formation from optically dense biofilm segments. In addition, quantitative measurements of biofilm velocity and optical density, combined with mathematical modeling, demonstrated that streamer formation occurred from mature, high-viscosity biofilms. We propose a streamer formation mechanism by sudden partial detachment, as opposed to continuous elongation as observed in other microfluidic studies. Additionally, streamer formation occurred in straight microchannels, as opposed to serpentine or pseudo-porous channels, as previously reported.
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Paquet-Mercier F, Karas A, Safdar M, Aznaveh NB, Zarabadi M, Greener J. Development and calibration of a microfluidic biofilm growth cell with flow-templating and multi-modal characterization. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2015; 2014:1557-62. [PMID: 25570268 DOI: 10.1109/embc.2014.6943900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We report the development of a microfluidic flow-templating platform with multi-modal characterization for studies of biofilms and their precursor materials. A key feature is a special three inlet flow-template compartment, which confines and controls the location of biofilm growth against a template wall. Characterization compartments include Raman imaging to study the localization of the nutrient solutions, optical microscopy to quantify biofilm biomass and localization, and cyclic voltammetry for flow velocity measurements. Each compartment is tested and then utilized to make preliminary measurements.
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Aznaveh NB, Safdar M, Wolfaardt G, Greener J. Micropatterned biofilm formations by laminar flow-templating. LAB ON A CHIP 2014; 14:2666-72. [PMID: 24722812 DOI: 10.1039/c4lc00084f] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We present a microfluidic device capable of patterning linear biofilm formations using a flow templating approach. We describe the design considerations and fabrication methodology of a two level flow-templating micro-bioreactor (FT-μBR), which generates a biofilm growth stream surrounded on 3 sides by a growth inhibiting confinement stream. Through a combination of experiments and simulations we comprehensively evaluate and exploit control parameters to manipulate the biofilm growth template stream dimensions. The FT-μBR is then used to grow biofilm patterns with controllable dimensions. A proof-of-principle study using the device demonstrates its utility in conducting biofilm growth rate measurements under different shear stress environments. This opens the way for quantitative studies into the effects of the local shear environment on biofilm properties and for the synthesis of a new generation of functional biomaterials with controllable properties.
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Voicu D, Abolhasani M, Choueiri R, Lestari G, Seiler C, Menard G, Greener J, Guenther A, Stephan DW, Kumacheva E. Microfluidic Studies of CO2 Sequestration by Frustrated Lewis Pairs. J Am Chem Soc 2014; 136:3875-80. [DOI: 10.1021/ja411601a] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Paquet-Mercier F, Aznaveh NB, Safdar M, Greener J. A microfluidic bioreactor with in situ SERS imaging for the study of controlled flow patterns of biofilm precursor materials. SENSORS 2013; 13:14714-27. [PMID: 24172286 PMCID: PMC3871105 DOI: 10.3390/s131114714] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2013] [Revised: 10/19/2013] [Accepted: 10/22/2013] [Indexed: 01/19/2023]
Abstract
A microfluidic bioreactor with an easy to fabricate nano-plasmonic surface is demonstrated for studies of biofilms and their precursor materials via Surface Enhanced Raman Spectroscopy (SERS). The system uses a novel design to induce sheath flow confinement of a sodium citrate biofilm precursor stream against the SERS imaging surface to measure spatial variations in the concentration profile. The unoptimised SERS enhancement was approximately 2.5 × 104, thereby improving data acquisition time, reducing laser power requirements and enabling a citrate detection limit of 0.1 mM, which was well below the concentrations used in biofilm nutrient solutions. The flow confinement was observed by both optical microscopy and SERS imaging with good complementarity. We demonstrate the new bioreactor by growing flow-templated biofilms on the microchannel wall. This work opens the way for in situ spectral imaging of biofilms and their biochemical environment under dynamic flow conditions.
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Voicu D, Scholl C, Li W, Jagadeesan D, Nasimova I, Greener J, Kumacheva E. Kinetics of Multicomponent Polymerization Reaction Studied in a Microfluidic Format. Macromolecules 2012. [DOI: 10.1021/ma300444k] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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38
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Petukhova A, Greener J, Liu K, Nykypanchuk D, Nicolaÿ R, Matyjaszewski K, Kumacheva E. Standing arrays of gold nanorods end-tethered with polymer ligands. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2012; 8:731-737. [PMID: 22228672 DOI: 10.1002/smll.201101297] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Revised: 11/16/2011] [Indexed: 05/31/2023]
Abstract
Nanomaterials with vectoral electromagnetic properties have potential applications in solar cells, plasmonic cavity resonators, light polarizers, and biosensing. Here a new, simple, solution-based method for producing nanomaterials comprising vertically aligned standing arrays of gold nanorods (NRs) end-functionalized with polymer ligands is reported. The method utilizes the side-by-side assembly of the NRs into large 2D superlattices, followed by the precipitation of the lattices on a solid substrate. The critical design rules for the self-assembly of superlattices are demonstrated, and they show the generality of the method by forming standing arrays from the NRs end-tethered with poly(N-vinylcarbazole) or with polystyrene molecules.
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Greener J, Tumarkin E, Debono M, Dicks AP, Kumacheva E. Education: a microfluidic platform for university-level analytical chemistry laboratories. LAB ON A CHIP 2012; 12:696-701. [PMID: 22237720 DOI: 10.1039/c2lc20951a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We demonstrate continuous flow acid-base titration reactions as an educational microfluidic platform for undergraduate and graduate analytical chemistry courses. A series of equations were developed for controlling and predicting the results of acid-base neutralisation reactions conducted in a microfluidic format, including the combinations of (i) a strong base and a strong acid, (ii) a strong base and a weak acid, and (iii) a strong base and a multiprotic acid. Microfluidic titrations yielded excellent repeatability. The small experimental footprint is advantageous in crowded teaching laboratories, and it offers limited waste and exposure to potentially hazardous acids and bases. This platform will help promote the utilisation of microfluidics at an earlier stage of students' careers.
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Li W, Liu K, Simms R, Greener J, Jagadeesan D, Pinto S, Günther A, Kumacheva E. Microfluidic Study of Fast Gas–Liquid Reactions. J Am Chem Soc 2012; 134:3127-32. [DOI: 10.1021/ja2101278] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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41
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Greener J, Tumarkin E, Debono M, Kwan CH, Abolhasani M, Guenther A, Kumacheva E. Development and applications of a microfluidic reactor with multiple analytical probes. Analyst 2011; 137:444-50. [PMID: 22108956 DOI: 10.1039/c1an15940b] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report the development of a versatile microfluidic (MF) reactor with multiple analytical probes, which can be used for (i) quantitative characterisation of molecular vibrational signatures of reactants or products, (ii) the localised real-time monitoring of temperature and (iii) site-specific measurements of pH of the reaction system. The analytical probes utilised for in situ reaction analysis include an ATR-FTIR probe, a temperature probe, and a pH probe. We demonstrate the applications of the MF reactor with integrated probes for the parallel monitoring of multiple variables in acid/base neutralisation reaction, of changes in buffer pH, temperature, and vibrational absorption bands, and for monitoring the kinetics of the reaction between CO(2) and a buffer system with therapeutic applications.
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Tumarkin E, Nie Z, Park JI, Abolhasani M, Greener J, Sherwood-Lollar B, Günther A, Kumacheva E. Temperature-controlled 'breathing' of carbon dioxide bubbles. LAB ON A CHIP 2011; 11:3545-3550. [PMID: 21869987 DOI: 10.1039/c1lc20490d] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We report a microfluidic (MF) approach to studies of temperature mediated carbon dioxide (CO(2)) transfer between the gas and the liquid phases. Micrometre-diameter CO(2) bubbles with a narrow size distribution were generated in an aqueous or organic liquid and subsequently were subjected to temperature changes in the downstream channel. In response to the cooling-heating-cooling cycle the bubbles underwent corresponding contraction-expansion-contraction transitions, which we term 'bubble breathing'. We examined temperature-controlled dissolution of CO(2) in four exemplary liquid systems: deionized water, a 0.7 M aqueous solution of NaCl, ocean water extracted from Bermuda coastal waters, and dimethyl ether of poly(ethylene glycol), a solvent used in industry for absorption of CO(2). The MF approach can be extended to studies of other gases with a distinct, temperature-dependent solubility in liquids.
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Kumachev A, Greener J, Tumarkin E, Eiser E, Zandstra PW, Kumacheva E. High-throughput generation of hydrogel microbeads with varying elasticity for cell encapsulation. Biomaterials 2010; 32:1477-83. [PMID: 21095000 DOI: 10.1016/j.biomaterials.2010.10.033] [Citation(s) in RCA: 170] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Accepted: 10/15/2010] [Indexed: 01/27/2023]
Abstract
Elasticity of cellular microenvironments strongly influences cell motility, phagocytosis, growth and differentiation. Currently, the relationship between the cell behaviour and matrix stiffness is being studied for cells seeded on planar substrates, however in three-dimensional (3D) microenvironments cells may experience mechanical signalling that is distinct from that on a two-dimensional matrix. We report a microfluidic approach for high-throughput generation of 3D microenvironments with different elasticity for studies of cell fate. The generation of agarose microgels with different elastic moduli was achieved by (i) introducing into a microfluidic droplet generator two streams of agarose solutions, one with a high concentration of agarose and the other one with a low concentration of agarose, at varying relative volumetric flow rate ratios of the two streams, and (ii) on-chip gelation of the precursor droplets. At 37 degreesC, the method enabled a approximately 35-fold variation of the shear elastic modulus of the agarose gels. The application of the method was demonstrated by encapsulating two mouse embryonic stem cell lines within the agarose microgels. This work establishes a foundation for the high-throughput generation of combinatorial microenvironments with different mechanical properties for cell studies.
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Greener J, Abbasi B, Kumacheva E. Attenuated total reflection Fourier transform infrared spectroscopy for on-chip monitoring of solute concentrations. LAB ON A CHIP 2010; 10:1561-1566. [PMID: 20376405 DOI: 10.1039/c001889a] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We report a cost-efficient Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR) method for monitoring concentrations of solutes in solutions flowing through microfluidic channels. The method allows rapid acquisition of spectra and enables chemical characterisation and concentration measurements that are independent of the flow rate of liquids. The method enables independent measurement of concentrations of solutes with distinct spectral features in mixed solutions. For the polymer solutes studied in the present work, the method has a sensitivity of at least 10 microM (0.01 wt%). We also propose the applicability of the method for the differentiation between dissolved and adsorbed amphiphilic species.
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Greener J, Li W, Ren J, Voicu D, Pakharenko V, Tang T, Kumacheva E. Rapid, cost-efficient fabrication of microfluidic reactors in thermoplastic polymers by combining photolithography and hot embossing. LAB ON A CHIP 2010; 10:522-4. [PMID: 20126695 DOI: 10.1039/b918834g] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
We report a cost-efficient and easy to implement process for fabricating microfluidic reactors in thermoplastic materials. The method includes (i) the fabrication of an imprint template (master), which consists of a photoresist deposited on a metal plate; (ii) the thermoembossing of the reactor features into polymer sheets; (iii) the activation of the embossed and planar thermoplastic surfaces; and (iv) the low-temperature bonding of these surfaces. The generality of the method is established by fabricating microfluidic reactors with a complex geometry in a range of thermoplastic polymers, including cycloolefin, polycarbonate, and UV-transparent acrylic polymers and by the multiple, high-fidelity use of the master.
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Li W, Greener J, Voicu D, Kumacheva E. Multiple modular microfluidic (M3) reactors for the synthesis of polymer particles. LAB ON A CHIP 2009; 9:2715-21. [PMID: 19704988 DOI: 10.1039/b906626h] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
We report a study of the continuous generation of polymer particles in parallel multiple modular microfluidic (M3) reactors. Each module consisted of sixteen parallel microfluidic reactors comprising emulsification and polymerization compartments. We identified and minimized the effects of the following factors that could result in the broadening of the distribution of sizes of the particles synthesized in the M3 reactors, in comparison with an individual microfluidic reactor: (i) the fidelity in the fabrication of multiple microfluidic droplet generators; (ii) the crosstalk between parallel droplet generators sharing liquid supply sources; and (iii) the coalescence of precursor droplets and/or partly polymerized polymer particles. Our results show that the M3 reactors can produce polymer microgel particles with polydispersity not exceeding 5% at a productivity of approximately 50 g/h.
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Zhao N, Liu K, Greener J, Nie Z, Kumacheva E. Close-packed superlattices of side-by-side assembled Au-CdSe nanorods. NANO LETTERS 2009; 9:3077-3081. [PMID: 19637890 DOI: 10.1021/nl901567a] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We report solution-based side-by-side self-assembly of Au-tipped CdSe nanorods (NRs) in large two-dimensional superlattices and the deposition of these lattices on a substrate with NRs aligned perpendicular to the surface. The side-by-side assembly of the NRs was triggered by changing the solvent quality for the ligands coating the long side of the nanorods. The stability of the self-assembled superlattices was enhanced due to the hydrogen bonding between the ligands attached to the Au tips of the nanorods. The reported approach can further facilitate the hierarchical integration of multicomponent NRs into functional devices.
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Greener J, van der Loop TH, Paquet C, Scholes G, Kumacheva E. A study of simultaneous patterning and alignment of semiconductor nanorods via polymerization-induced phase separation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:3173-3177. [PMID: 19437720 DOI: 10.1021/la803521t] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We report simultaneous patterning and alignment of semiconductor nanorods (NRs) in nanorod-polymer films by using photolithographic polymerization-induced phase separation (PIPS). Exposure of the nanoparticle-monomer mixture to UV irradiation through a mask resulted in the site-specific photoinitiated polymerization of the monomer, which was followed with flow of the NRs from the areas rich in polymer to the areas rich in monomer. The orientation of NRs in the direction of flow was trapped in the polymerized films and characterized in polarization absorption experiments.
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Greener J, Ng KC, Vaeth KM, Smith TM. Moisture permeability through multilayered barrier films as applied to flexible OLED display. J Appl Polym Sci 2007. [DOI: 10.1002/app.26863] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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50
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Greener J, Tsou AH, Blanton TN. Physical and microstructural effects of heat setting in polyester films. POLYM ENG SCI 2004. [DOI: 10.1002/pen.11629] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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