scholarly journals Acoustic focusing of beads and cells in hydrogel droplets

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Anna Fornell ◽  
Hannah Pohlit ◽  
Qian Shi ◽  
Maria Tenje
Keyword(s):  
Polyethylene Glycol ◽  
Uv Light ◽  
Precursor Solution ◽  
Microfluidic System ◽  
Nodal Line ◽  
Droplet Microfluidics ◽  
Acoustic Standing Wave ◽  
Centre Line ◽  
Half Wavelength ◽  
Acoustic Focusing

AbstractThe generation of hydrogel droplets using droplet microfluidics has emerged as a powerful tool with many applications in biology and medicine. Here, a microfluidic system to control the position of particles (beads or astrocyte cells) in hydrogel droplets using bulk acoustic standing waves is presented. The chip consisted of a droplet generator and a 380 µm wide acoustic focusing channel. Droplets comprising hydrogel precursor solution (polyethylene glycol tetraacrylate or a combination of polyethylene glycol tetraacrylate and gelatine methacrylate), photoinitiator and particles were generated. The droplets passed along the acoustic focusing channel where a half wavelength acoustic standing wave field was generated, and the particles were focused to the centre line of the droplets (i.e. the pressure nodal line) by the acoustic force. The droplets were cross-linked by exposure to UV-light, freezing the particles in their positions. With the acoustics applied, 89 ± 19% of the particles (polystyrene beads, 10 µm diameter) were positioned in an area ± 10% from the centre line. As proof-of-principle for biological particles, astrocytes were focused in hydrogel droplets using the same principle. The viability of the astrocytes after 7 days in culture was 72 ± 22% when exposed to the acoustic focusing compared with 70 ± 19% for samples not exposed to the acoustic focusing. This technology provides a platform to control the spatial position of bioparticles in hydrogel droplets, and opens up for the generation of more complex biological hydrogel structures.

Fabrication of PEG Hydrogel and PDMS Microstructures by a Simple UV Curing Process for Nanobio-Chip Applications

2014 ◽  
Vol 941-944 ◽  
pp. 404-410 ◽  
Author(s):  
Young Ho Kim ◽  
Jeong Woo Sohn ◽  
Youngjae Woo ◽  
Joo Hyun Hong ◽  
Juyoung Park
Keyword(s):  
Polyethylene Glycol ◽  
Uv Irradiation ◽  
Large Scale ◽  
Uv Light ◽  
Single Step ◽  
Polydimethyl Siloxane ◽  
Polyethylene Glycol Diacrylate ◽  
Glycol Diacrylate ◽  
Metal Mask ◽  
Glass Chip

Polyethylene glycol (PEG) hydrogel microstructures with various shapes and sizes on a glass chip were prepared by a simple and rapid ultraviolet (UV) irradiation method using a metal mask. Photocurable PEG solution prepared by mixing 95 wt.% polyethylene glycol diacrylate and 5 wt.% 2-hydroxy-2-methylpropiophenone as a photo-initiator was injected to the gap between bottom and upper glasses in a simply assembled glass chip. After a metal mask with line-and-space or complex patterns was placed on the glass chip, UV light from a spot UV irradiation device was exposed to the glass chip through the metal mask for 7 seconds at UV intensity of 26 mW/cm2. Then the PEG hydrogel micropatterns on the glass chip were obtained after removing unreacted PEG solution by air blowing. To prepare more rigid microstructure, the prepared PEG micropatterned chip was exposed under UV light for 20 seconds. Then the PEG hydrogel micropattern chip was fabricated by a simple and rapid procedure. Micropattern transferring was performed from the PEG hydrogel chip to polydimethyl siloxane (PDMS) replica by a solution casting. The prepared micropatterned PDMS replicas showed similar shape and size of microstructures compared to that of the corresponded PEG hydrogel chip. Thus the PEG hydrogel microstructures on a glass chip could be used as a mold to fabricate micropattern PDMS chips for nanobio-chip applications. Furthermore, the present method provides large scale chip fabrication, more than 4 cm-length and 4 cm-width in a single step, not only PEG hydrogel chips but also PDMS chips.

scholarly journals Single-step synthesis of three-dimensional particles using non-uniform UV polymerization

2021 ◽  
Author(s):  
Navid Hakimi
Keyword(s):  
Uv Light ◽  
Three Dimensional ◽  
Microfluidic Channel ◽  
Precursor Solution ◽  
Monomer Conversion ◽  
Single Step ◽  
Shape Dependence ◽  
Straightforward Method ◽  
One Step ◽  
Stop Flow

Polymer-based microparticles are increasingly utilized in a range of biotechnology application. There is growing evidence that microparticle shape is an important parameter governing its functionality. Yet, there currently exists no straightforward method to controllably synthesize a large number of highly three-dimensional (3D) microparticles. In this thesis, we develop a one-step two-dimensional (2D) stop-flow lithography method that exploits the non-uniformity of the polymerizing ultraviolet (UV) light, UV adsorption by opaque nanoparticles in the precursor solution, and discontinuous photomask patterns, to make highly curved 3D microparticles. We investigate the microparticle shape dependence on each parameter by independently tuning the field and focus of the UV light, adding opaque magnetic nanoparticles to the precursor solution, and using a variety of photomask patterns.We also perform numerical simulations of oxygen concentration and monomer conversion in the microfluidic channel, to predict the particle shape. By simplifying the synthesis of high curvature 3D particles with 3D surface features and branched structures, our method may lead to the expanded use of microparticles in research and in industry.

The Photoelectrochemical Characteration of Porous Titania Dioxide Thin Films Prepared by PEG-Assisted Sol-Gel Method

2009 ◽  
Vol 79-82 ◽  
pp. 943-946
Author(s):  
Ai Ping Wang ◽  
Yan Sheng Yin ◽  
Hong Feng Wang ◽  
Zhi Bin Zhu ◽  
Ming Hui He
Keyword(s):  
Thin Films ◽  
Cyclic Voltammetry ◽  
Polyethylene Glycol ◽  
Uv Light ◽  
Sol Gel ◽  
Tio2 Thin Films ◽  
Photoelectrochemical Activity ◽  
Gel Method ◽  
Sol Gel Method ◽  
Porous Titania

Nanocrystalline titania porous films were prepared on ITO and glass substrates by polyethylene glycol（PEG）-assisted sol-gel method using Ti(C4H9COO)4 as precursor, ethanol as solvent and NH(C2H2OH)2 as chelating agent and PEG 2000as a template. When the amount of polyethylene glycol is within the range of 0～2. 0g/L ,. The characteristics and microstructure of films as well as the chemical and physical changes taken place during so-gel and heat treatments were analyzed by XRD, SEM and Emission spectra. The Cyclic voltammetry which measurements the films by illumination with a high pressure mercury lamp are employed to analyze photoelectrochemical property the porous titania thin films. The effects of precursor concentration and PEG 2000 contention the characteristic of films were discussed. The Cyclic voltammetry experiment under UV light irradiation indicated that the pores in the TiO2 thin films enhanced its photoelectrochemical activity; the size of the pores thin films obviously affected the photo-current exchanged rate of titania films.

INFLUENCE OF TITANIUM TETRAISOPROPOXIDE CONCENTRATION ON THE ANTIBACTERIAL ACTIVITY OF TiO2 THIN FILMS

2018 ◽  
Vol 25 (06) ◽  
pp. 1850111 ◽  
Author(s):  
ALI A. TAHA ◽  
SELMA M. H. AL-JAWAD ◽  
MOHAMMED M. SALIM
Keyword(s):  
Thin Films ◽  
Antibacterial Activity ◽  
Uv Light ◽  
Sol Gel ◽  
Precursor Solution ◽  
Titanium Tetraisopropoxide ◽  
Tio2 Thin Films ◽  
Force Microscopy ◽  
Xrd Patterns ◽  
Titanium Dioxide Thin Films

In this study, titanium dioxide thin films were successfully prepared via sol–gel method. Titanium tetraisopropoxide (TTIP) as a precursor solution was used to prepare different concentrations and deposited by spin coating. All prepared films were inspected by X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM). XRD patterns show that all samples have anatase crystal structure. Transmittance spectra were measured by using UV-Vis spectrophotometer. The optical band gaps were 3.55, 3.62 and 3.78 eV for TTIP concentrations of 6, 6.3 and 6.6[Formula: see text]ml, respectively. Antibacterial activity of TiO2 films against S. aureus and E. coli was evaluated by international recognized test (JIS Z 2801). The test revealed incrementally increase in antibacterial activity of the films with TTIP concentrations activated by UV light.

scholarly journals Photocatalytic Activity of Fibrous Ti/Ce Oxides Obtained by Hydrothermal Impregnation of Short Flax Fibers

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3399
Author(s):  
Mikhail F. Butman ◽  
Nataliya E. Kochkina ◽  
Nikolay L. Ovchinnikov ◽  
Karl W. Krämer
Keyword(s):  
Photocatalytic Activity ◽  
Uv Light ◽  
Solution Process ◽  
Precursor Solution ◽  
Pure Tio2 ◽  
Photocatalytic Decomposition ◽  
Surface Irregularity ◽  
Hydrothermal Conditions ◽  
Flax Fibers ◽  
Vis Spectroscopy

Fibrous Ti/Ce oxide photocatalysts were prepared for the first time by a biomimetic solution process using short flax fibers (flax straw processing waste) as a biotemplate. Titanium polyhydroxy complex solutions with 3% and 5% cerium were used as precursors. Flax fibers were impregnated in an autoclave under hydrothermal conditions. Ti/Ce oxides were obtained from the biotemplate by annealing at 600 °C. The photocatalytic activity of the Ti/Ce oxides was studied by the adsorption and decomposition of the dye rhodamine B under UV irradiation. The photocatalytic decomposition of the dye was 50% and 75% faster for Ti/Ce oxides with 3% and 5% Ce, respectively, than for the analogous undoped fibrous TiO2. The morphologies, textures, and structures of the photocatalysts were studied by scanning electron microscopy, low temperature N2 adsorption/desorption, UV-Vis spectroscopy, and X-ray and XPS analytical methods. It was shown that the introduction of Ce into the precursor solution increased the surface irregularity of the Ti/Ce oxide crystallites compared to pure TiO2. This effect scaled with the Ce concentration. Ce improved the UV light absorption of the material. The Ti/Ce oxides contained Ce4+/Ce3+ pairs that played an important role in redox processes and intensified the photocatalytic activity.

scholarly journals THE EFFECT OF SOL-GEL TEMPERATURE AND SOLVENT POLYETHYLENE GLYCOL (PEG) IN ZnO- TiO2 PHOTOCATALYST ACT AS DEGRADER OF TEXTILE DYEING LIQUID WASTE

2016 ◽  
Vol 10 (2) ◽  
pp. 149
Author(s):  
Tanti Haryati ◽  
Novita Andarini ◽  
Siti Mardhiyah
Keyword(s):  
Crystal Structure ◽  
Photocatalytic Activity ◽  
Polyethylene Glycol ◽  
Uv Light ◽  
Sol Gel ◽  
Liquid Waste ◽  
Synthesis Temperature ◽  
Tio2 Photocatalyst ◽  
Textile Dyeing ◽  
Gel Temperature

<p>The use of TiO<sub>2</sub>  powder  as photocatalyst still provides some disadvantages such as the difficulties in regenerate ion, the low adsorption and turbulence . These problems can be overcomed by providing the photocatalyst as a composite of ZnO-TiO2. This research aims to  investigate  the  effect  of  composition  of  solvent  and  temperatureof  synthesis  on  the quality  and  photocatalytic  activity  of  ZnO-TiO2  which  was  prepared  by  sol-gel  method. The  photocatalytic  activity  was  determined  by  applying  the  composite  in  degradation  of Procion  Red  MX-8B  under  irradition  of  UV  light  for  24  hours.  The  procion  red concentration after degradation was determined by UV-Vis spectrophotometer. Meanwhile the effect of synt hesis temperature on crystal structure  of composite  was studied by XRD. The results show that the composite which was prepared by PEG 1500 at 1:4 of moles ratio and at 70  °C of  synthesis temperature has  highest degradation  percentage,  i.e. 55.375 % and photocataltic activity of 3.561 x 10<sup>-7</sup>mg/cm<sup>2</sup>s.</p>

Moldable Perfluoropolyether–Polyethylene Glycol Networks with Tunable Wettability and Solvent Resistance for Rapid Prototyping of Droplet Microfluidics

2018 ◽  
Vol 30 (8) ◽  
pp. 2583-2588 ◽  
Author(s):  
Heon-Ho Jeong ◽  
Syung Hun Han ◽  
Sagar Yadavali ◽  
Junhyong Kim ◽  
David Issadore ◽  
...  
Keyword(s):  
Polyethylene Glycol ◽  
Rapid Prototyping ◽  
Droplet Microfluidics ◽  
Solvent Resistance

scholarly journals Preparation ofNaTaO3by Spray Pyrolysis and Evaluation of Apparent Photocatalytic Activity for Hydrogen Production from Water

2008 ◽  
Vol 2008 ◽  
pp. 1-8 ◽  
Author(s):  
Hyun Woo Kang ◽  
Eun-Jung Kim ◽  
Seung Bin Park
Keyword(s):  
Photocatalytic Activity ◽  
Quantum Yield ◽  
Hydrogen Production ◽  
Spray Pyrolysis ◽  
Uv Light ◽  
Precursor Solution ◽  
Photocatalytic Reactor ◽  
Photocatalytic Activities ◽  
Uv Lamp ◽  
Spray Pyrolysis Process

NaTaO3photocatalyst was prepared by spray pyrolysis process and tested as photocatalyst for water splitting under UV light. Precursor solution was prepared fromNaNO3andTa(OC2H5)5in nitric acid solution and spray-pyrolyzed in air at between 973 and 1273 K. Considerable enhancement of photocatalytic activity was achieved by loading0.05∼0.2 wt% of NiO on the surface ofNaTaO3. The NiO loading was more effective on theNaTaO3synthesized by spray pyrolysis in comparison with that synthesized by solid-state reaction. The quantum yield (QY) ofNiO/NaTaO3photocatalyst was measured by chemical actinometry using potassium ferrioxalate and compared with the apparent photocatalytic activities (APA) which would be more useful for the purpose of photocatalytic reactor design than the quantum yield. The apparent photocatalytic activity (APA) was defined by the rate of hydrogen production divided by weight of catalyst, volume of reactant mixture, duration of irradiation, and power of UV lamp. The validity of the apparent photocatalytic activity (APA) was discussed based on our results and reported activities ofNaTaO3photocatalyst loaded with or without NiO.

scholarly journals Single-step synthesis of three-dimensional particles using non-uniform UV polymerization

2021 ◽  
Author(s):  
Navid Hakimi
Keyword(s):  
Uv Light ◽  
Three Dimensional ◽  
Microfluidic Channel ◽  
Precursor Solution ◽  
Monomer Conversion ◽  
Single Step ◽  
Shape Dependence ◽  
Straightforward Method ◽  
One Step ◽  
Stop Flow

Polymer-based microparticles are increasingly utilized in a range of biotechnology application. There is growing evidence that microparticle shape is an important parameter governing its functionality. Yet, there currently exists no straightforward method to controllably synthesize a large number of highly three-dimensional (3D) microparticles. In this thesis, we develop a one-step two-dimensional (2D) stop-flow lithography method that exploits the non-uniformity of the polymerizing ultraviolet (UV) light, UV adsorption by opaque nanoparticles in the precursor solution, and discontinuous photomask patterns, to make highly curved 3D microparticles. We investigate the microparticle shape dependence on each parameter by independently tuning the field and focus of the UV light, adding opaque magnetic nanoparticles to the precursor solution, and using a variety of photomask patterns.We also perform numerical simulations of oxygen concentration and monomer conversion in the microfluidic channel, to predict the particle shape. By simplifying the synthesis of high curvature 3D particles with 3D surface features and branched structures, our method may lead to the expanded use of microparticles in research and in industry.

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