Combining magnetic forces for contactless manipulation of fluids in microelectrode-microfluidic systems

Haehnel, Veronika; Khan, Foysal Z.; Mutschke, Gerd; Cierpka, Christian; Uhlemann, Margitta; Fritsch, Ingrid

doi:10.1038/s41598-019-41284-0

Cited by 11 publications

(6 citation statements)

References 37 publications

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“…Here, we demonstrate the usage of RMHD–DFM as an efficient tool to both evaluate the NP sizes and simultaneously differentiate between mixtures of different nanomaterials. In addition, the presence of a magnetic field gradient can offer an extra factor of influence on the mass transport, − separation, , and interactions of (super)paramagnetic NPs . In addition, this method is well suited for probing samples with low NP concentrations.…”

Section: Discussionmentioning

confidence: 99%

Characterization of Nanoparticles in Diverse Mixtures Using Localized Surface Plasmon Resonance and Nanoparticle Tracking by Dark-Field Microscopy with Redox Magnetohydrodynamics Microfluidics

et al. 2022

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Redox magnetohydrodynamics (RMHD) microfluidics is coupled with dark-field microscopy (DFM) to offer high-throughput single-nanoparticle (NP) differentiation in situ and operando in a flowing mixture by localized surface plasmon resonance (LSPR) and tracking of NPs. The color of the scattered light allows visualization of the NPs below the diffraction limit. Their Brownian motion in 1-D superimposed on and perpendicular to the RMHD trajectory yields their diffusion coefficients. LSPR and diffusion coefficients provide two orthogonal modalities for characterization where each depends on a particle's material composition, shape, size, and interactions with the surrounding medium. RMHD coupled with DFM was demonstrated on a mixture of 82 ± 9 nm silver and 140 ± 10 nm gold-coated silica nanospheres. The two populations of NPs in the mixture were identified by blue/green and orange/red LSPR and their scattering intensity, respectively, and their sizes were further evaluated based on their diffusion coefficients. RMHD microfluidics facilitates high-throughput analysis by moving the sample solution across the wide field of view absent of physical vibrations within the experimental cell. The well-controlled pumping allows for a continuous, reversible, and uniform flow for precise and simultaneous NP tracking of the Brownian motion. Additionally, the amounts of nanomaterials required for the analysis are minimized due to the elimination of an inlet and outlet. Several hundred individual NPs were differentiated from each other in the mixture flowing in forward and reverse directions. The ability to immediately reverse the flow direction also facilitates re-analysis of the NPs, enabling more precise sizing.

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Section: Discussionmentioning

confidence: 99%

Characterization of Nanoparticles in Diverse Mixtures Using Localized Surface Plasmon Resonance and Nanoparticle Tracking by Dark-Field Microscopy with Redox Magnetohydrodynamics Microfluidics

et al. 2022

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“…Previous studies have already demonstrated the accelerated transport of paramagnetic ions through porous membranes in magnetic fields. 53 , 54 The introduction of a liquid flow, 55 as is routinely done in flow-by capacitive deionization cells, provides ample opportunities for study.…”

Section: Discussionmentioning

confidence: 99%

“…Such a cell may integrate small magnets or even incorporate a magnetic material directly in the porous electrode, , thus generating larger magnetic field gradients. Previous studies have already demonstrated the accelerated transport of paramagnetic ions through porous membranes in magnetic fields. , The introduction of a liquid flow, as is routinely done in flow-by capacitive deionization cells, provides ample opportunities for study.…”

Section: Discussionmentioning

confidence: 99%

Neutron Imaging of Paramagnetic Ions: Electrosorption by Carbon Aerogels and Macroscopic Magnetic Forces

et al. 2021

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The electrosorption of Gd 3+ ions from an aqueous 70 mM Gd(NO 3 ) 3 solution in monolithic carbon aerogel electrodes was recorded by dynamic neutron imaging. The aerogels have a bimodal pore size distribution consisting of macropores and mesopores centered at 115 and 15 nm, respectively. After the uptake of Gd 3+ ions by the negatively charged surface of the porous structure, an inhomogeneous magnetic field was applied to the system of discharging electrodes. This led to a convective flow and confinement of Gd(NO 3 ) 3 solution in the magnetic field gradient. Thus, a way to desalt and capture paramagnetic ions from an initially homogeneous solution is established.

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“…Previous studies have already demonstrated the acceleration of transport of paramagnetic ions through a porous membrane in magnetic fields [49,50]. The introduction of a liquid flow [51], as is routinely done in flow-by desalination cells, provides ample opportunities for study. Neutron imaging with higher temporal and spatial resolutions [52][53][54] along with the unlocking of small-angle neutron scattering information via dark-field imaging [55][56][57] offer intriguing possibilities for future investigation of these ideas.…”

Section: Discussionmentioning

confidence: 99%

Neutron Imaging of Paramagnetic Ions: Electrosorption by Carbon Aerogels and Macroscopic Magnetic Forces

Butcher,

Prendeville,

Rafferty

et al. 2021

Preprint

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The electrosorption of Gd 3+ ions from aqueous 70 mM Gd(NO3)3 solution in monolithic carbon aerogel electrodes was recorded by dynamic neutron imaging. The aerogels have a bimodal pore size distribution consisting of macropores centred at 115 nm and mesopores centred at 15 nm. After the uptake of Gd 3+ ions by the negatively charged surface of the porous structure, an inhomogeneous magnetic field was applied to the system of discharging electrodes. This led to a convective flow and confinement of Gd(NO3)3 solution in the magnetic field gradient. Thus, a way to desalt and capture paramagnetic ions from an initially homogeneous solution is established.

show abstract

Combining magnetic forces for contactless manipulation of fluids in microelectrode-microfluidic systems

Cited by 11 publications

References 37 publications

Characterization of Nanoparticles in Diverse Mixtures Using Localized Surface Plasmon Resonance and Nanoparticle Tracking by Dark-Field Microscopy with Redox Magnetohydrodynamics Microfluidics

Characterization of Nanoparticles in Diverse Mixtures Using Localized Surface Plasmon Resonance and Nanoparticle Tracking by Dark-Field Microscopy with Redox Magnetohydrodynamics Microfluidics

Neutron Imaging of Paramagnetic Ions: Electrosorption by Carbon Aerogels and Macroscopic Magnetic Forces

Neutron Imaging of Paramagnetic Ions: Electrosorption by Carbon Aerogels and Macroscopic Magnetic Forces

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