Three-dimensional Channel Networks Research Articles

Study on Performance Simulation of Vascular-like Flow Channel Model Based on TPMS Structure

In medical validation experiments, such as drug testing and clinical trials, 3D bioprinted biomimetic tissues, especially those containing blood vessels, can be used to replace animal models. The difficulty in the viability of printed biomimetic tissues, in general, lies in the provision of adequate oxygen and nutrients to the internal regions. This is to ensure normal cellular metabolic activity. The construction of a flow channel network in the tissue is an effective way to address this challenge by both allowing nutrients to diffuse and providing sufficient nutrients for internal cell growth and by removing metabolic waste in a timely manner. In this paper, a three-dimensional TPMS vascular flow channel network model was developed and simulated to analyse the effect of perfusion pressure on blood flow rate and vascular-like flow channel wall pressure when the perfusion pressure varies. Based on the simulation results, the in vitro perfusion culture parameters were optimised to improve the structure of the porous structure model of the vascular-like flow channel, avoiding perfusion failure due to unreasonable perfusion pressure settings or necrosis of cells without sufficient nutrients due to the lack of fluid passing through some of the channels, and the research work promotes the development of tissue engineering in vitro culture.

Design and Optimization of a Natural Medicine from Copaifera reticulata Ducke for Skin Wound Care.

In this study, we developed a bioadhesive emulsion-filled gel containing a high amount of Copaifera reticulata Ducke oil-resin as a veterinary or human clinical proposal. The phytotherapeutic system had easy preparation, low cost, satisfactory healing ability, and fly repellency, making it a cost-effective clinical strategy for wound care and myiasis prevention. Mechanical, rheological, morphological, and physical stability assessments were performed. The results highlight the crosslinked nature of the gelling agent, with three-dimensional channel networks stabilizing the Copaifera reticulata Ducke oil-resin (CrD-Ore). The emulgel presented antimicrobial activity, satisfactory adhesion, hardness, cohesiveness, and viscosity profiles, ensuring the easy spreading of the formulation. Considering dermatological application, the oscillatory responses showed a viscoelastic performance that ensures emulgel retention at the action site, reducing the dosage frequencies. In Vivo evaluations were performed using a case report to treat ulcerative skin wounds aggravated by myiasis in calves and heifers, which demonstrated healing, anti-inflammatory, and repellent performance for the emulsion-filled gel. The emulgel preparation, which is low in cost, shows promise as a drug for wound therapy.

Beneficial impact of incorporating spinel lithium manganate and samarium oxide into high performance positive materials through ultrasonic cavitation strategy

Spinel LiMn2O4 (LMO) positive material has the advantage of a robust structure with a three-dimensional network of channels for fast Li+ conduction, which is one of the hot topics in the zero-cobalt electrodes field of new energy technology. Nonetheless, the spinel LiMn2O4 has serious transition metal dissolution as well as phase/surface stability problems, resulting in unsatisfactory cycle performance which hinders large scale applications in the field of lithium-ion batteries. In this study, Sm2O3 surface modified LiMn2O4 positive material is obtained by a facile ultrasonic cavitation combined with sol-gel strategy. The structural and surface morphological are analyses by X-ray diffraction, X-ray photoelectron spectroscopy and high resolution transmission electron microscopy illuminate the formation of the Sm2O3-coated LiMn2O4. Electrochemical analysis revealed that the LMO particles coated by the 1 wt% Sm2O3 is exhibited the best electrochemical performance among other coated and non-coated samples, with an initial capacity of 110.92 mAh g−1 and a capacity retention of 94.79% after 200 cycles. Furthermore, ICP analysis is showed that the manganese dissolution of the modified material in organic electrolyte is much lower than that of pristine sample. This work may provoke wide interests in surface modification areas and motivate the further improvement of the electrochemical performance for other commercialized spinel lithium ion batteries (LIBs).

A Novel-Type Microporous Heteropolyhedral Framework in Crystal Structure of the Natural Sulfate Philoxenite

The crystal structure of a new mineral philoxenite (K,Na,Pb)4(Na,Ca)2(Mg,Cu)3(Fe $$_{{0.5}}^{{3 + }}$$ Al0.5)(SO4)8 from fumarole exhalations of the Tolbachik Volcano (Kamchatka, Russia) has been determined by single-crystal X-ray diffraction analysis (R1 = 5.67%). Philoxenite is triclinic (sp. gr. P $$\bar {1}$$ ) with the following parameters: a = 8.8410(3) A, b = 8.9971(3) A, c = 16.1861(5) A, α = 91.927(3)°, β = 94.516(3)°, γ = 90.118(3)°, V = 1282.77(7) A3, and Z = 2. The mineral has a unique structure based on a new-type microporous heteropolyhedral framework formed by SO4 tetrahedra and M(1–4)O6 octahedra of four types. It is pierced with a three-dimensional network of channels with large cations occupying seven different sites А(1–7). The philoxenite structural formula (Z = 1) is A(2,6)(K0.90Na0.07Pb0.03)4 A(5)(K0.69Na0.28Pb0.03)2 A(7)(K0.85Pb0.15)2 A(1)(Na0.61Ca0.39)2- A(3)(Na0.72Ca0.28)A(4)(Na0.81Ca0.19)M(2)(Mg0.60Cu $$_{{0.40}}^{{2 + }}$$ )2M(1)(Mg0.56Cu $$_{{0.44}}^{{2 + }}$$ )2M(4)(Mg0.43Al0.35Zn0.22)2- M(3)(Fe $$_{{0.42}}^{{3 + }}$$ Al0.40Mg0.18)2(SO4)16.

Microchannel network hydrogel induced ischemic blood perfusion connection

Angiogenesis induction into damaged sites has long been an unresolved issue. Local treatment with pro-angiogenic molecules has been the most common approach. However, this approach has critical side effects including inflammatory coupling, tumorous vascular activation, and off-target circulation. Here, the concept that a structure can guide desirable biological function is applied to physically engineer three-dimensional channel networks in implant sites, without any therapeutic treatment. Microchannel networks are generated in a gelatin hydrogel to overcome the diffusion limit of nutrients and oxygen three-dimensionally. Hydrogel implantation in mouse and porcine models of hindlimb ischemia rescues severely damaged tissues by the ingrowth of neighboring host vessels with microchannel perfusion. This effect is guided by microchannel size-specific regenerative macrophage polarization with the consequent functional recovery of endothelial cells. Multiple-site implantation reveals hypoxia and neighboring vessels as major causative factors of the beneficial function. This technique may contribute to the development of therapeutics for hypoxia/inflammatory-related diseases.

Preparation and performances of novel Na2FeSiO4/C composite with more stable polymorph as cathode material of sodium-ion batteries

The sodium orthosilicates as the potential candidates of cathode materials in sodium-ion batteries capture tremendous interests because of the low costs, robustly crystal structure and high specific capacity. However, like lithium orthosilicates, the crystal structure, morphology and electrochemical properties of the polycrystalline sodium orthosilicates need to be properly designed so that sodium ion can be smoothly intercalated/deintercalated. Herein, a novel orthorhombic Pb21a–Na2FeSiO4/C, which is obtained from the conversion of C2221–Na2FeSiO4/C, is prepared and used as cathode material for the first time. Meanwhile, the pure phase C2221–Na2FeSiO4/C is firstly prepared by sol-gel method. Field emission scanning and transmission electron microscopy demonstrate that C2221–Na2FeSiO4/C has quasi-spherical morphology, and the active nanoparticles completely disperse within the cross-linked carbon nanolayer. The results from X-ray diffraction and Rietveld analysis reveal that the crystal structure of Pb21a–Na2FeSiO4/C, similarly to C2221–Na2FeSiO4/C, can be formed by three-dimensional channel networks which generate from the alternate tetrahedral geometry chains of [FeO4] and [SiO4], but Pb21a–Na2FeSiO4/C composite is more stable than C2221–Na2FeSiO4/C. After the first sodiation/desodiation process, Pb21a–Na2FeSiO4/C shows the specific capacity of 118 mAh g−1 at 0.1 C and a capacity retention of 57.3% after 100 cycles.

Fabrication and Demonstration of Planar Micro-Reactors for Solar Steam Methane Reforming

This paper presents a novel solar micro-reactor architecture for cheap hydrogen production by methane reforming. Using microfabrication techniques to create three-dimensional channel networks in diffusion-bonded plates, all the sub-processes required for methane reforming are integrated in a small unit, which is well suited for implementation on cheap and well-established solar parabolic troughs. Monolithic integration of the sub-processes allows heat recovery from the high temperature reaction to the lower temperature endothermic processes such as water vaporization and reagent preheating. To demonstrate the manufacturing feasibility as well as the sufficient catalytic activity, a 4.5W stainless steel demonstrator is built and tested in the laboratory. Results show a complete methane conversion for temperatures over 850°C at a space velocity of 35 000 ml/h*mlcat.

Geometrical effect characterization of femtosecond-laser manufactured glass microfluidic chips based on optical manipulation of submicroparticles

Microfluidic devices provide a platform with wide ranging applications from environmental monitoring to disease diagnosis. They offer substantive advantages but are often not optimized or designed to be used by nonexpert researchers. Microchannels of a microanalysis platform and their geometrical characterization are of eminent importance when designing such devices. We present a method that is used to optimize each microchannel within a device using high-throughput particle manipulation. For this purpose, glass-based microfluidic devices, with three-dimensional channel networks of several geometrical sizes, were fabricated by employing laser fabrication techniques. The effect of channel geometry was investigated by employing an optical tweezer. The optical trapping force depends on the flow velocity that is associated with the dimensions of the microchannel. We observe a linear dependence of the trapping efficiency and of the fluid flow velocity, with the channel dimensions. We determined that the highest trapping efficiency was achieved for microchannels with aspect ratio equal to one. Numerical simulation validated the impact of the device design dimensions on the trapping efficiency. This investigation indicates that the geometrical characteristics, the flow velocity, and trapping efficiency are crucial and should be considered when fabricating microfluidic devices for cell studies.

Ultralow voltage operation of biologically assembled all carbon nanotube nanomesh transistors with ion-gel gate dielectrics

The demonstration of field-effect transistors (FETs) based entirely on single-walled carbon nanotubes (SWNTs) would enable the fabrication of high-on-current, flexible, transparent and stretchable devices owing to the excellent electrical, optical, and mechanical properties of SWNTs. Fabricating all-SWNT-based FETs via simple solution process, at room temperature and without using lithography and vacuum process could further broaden the applicability of all-SWNT-FETs. In this work, we report on biologically assembled all SWNT-based transistors and demonstrate that ion-gel-gated network structures of unsorted SWNTs assembled using a biological template material enabled operation of SWNT-based transistors at a very low voltage. The compatibility of the biologically assembled SWNT networks with ion gel dielectrics and the large capacitance of both the three-dimensional channel networks and the ion gel allowed an ultralow operation voltage. The all-SWNT-based FETs showed an Ion/Ioff value of >102, an on-current density per channel width of 2.16 × 10−4 A/mm at VDS = 0.4 V, and a field-effect hole mobility of 1.12 cm2/V · s in addition to the low operation voltage of <−0.5 V. We envision that our work suggests a solution-based simple and low-cost approach to realizing all-carbon-based FETs for low voltage operation and flexible applications.

Controllable synthesis of composites of ZSM-5 and KIT-1 using an ionic liquid as template

ZSM-5/KIT-1 composites were synthesized using an ionic liquid as a template. The structures and morphologies of as-obtained products were characterized using an infrared spectroscopy, X-ray diffractometer, N2 adsorption/desorption, scanning electron microscopy and transmission electron microscopy. The resultant zeolites show a fully crystalline microporous MFI zeolite framework and a three-dimensional network of short worm-like channels. Mesopores and microspores of 4.2 and 0.8 nm in diameter coexist in the zeolite composites. Moreover, the ratio of ZSM-5 and KIT-1 could be simply adjusted by controlling the pre-crystalline time. We believe that the strategy for fabricating ZSM-5/KIT-1 through a simple method could potentially promote the large-scale production of zeolite composites.

INVESTIGATION OF NANO- AND MICROSTRUCTURE OF BIOMATERIALS FOR REGENERATIVE MEDICINE BY METHOD OF SCANNING PROBE NANOTOMOGRAPHY

Aim. To perform a study of three-dimensional micro- and nanostructure of porous biocompatible scaffolds and quantitative analysis of nanoscale porosity parameters. Materials and methods . Three-dimensional porous scaffolds made from spidroin rS1/9 (recombinant analog of spider dragline protein) were produced by salt leaching technique. Dimensions of macropores in produced three-imensional scaffolds were in range from 200 to 400 microns. The study of three-dimensional structure of scaffolds was carried out by scanning probe nanotomography technique with the use of experimental setup combining ultramicrotome and scanning probe microscope. Results. Three-dimensional nanotomographical reconstruction of scaffold macropore wall structure is obtained. The formation of three-dimensional network of interconnected pores and channels with characteristic dimensions in range from 20 to 700 nm in the volume of macropore walls of studied scaffolds is observed. Mean pore diameter is 150 nm. Volume porosity of macropore walls is 22% while volume fraction of pores interconnected in large pore clusters is about 20% of all pore volume. Conclusion. Obtained as a result of the study quantitative characteristics of porous micro- and nanostructure of scaffolds show signifi cant degree of nanoscale porosity and percolation of macropore walls what correlates with reported high effi ciency of tissue regeneration on such scaffolds implanted in vivo. Use of scanning probe nanotomography technique for analysis of characteristics and topology of micro- and nanopore systems enables to improve effi ciency of development of novel biocompatible and biodegradable materials with predicted morphological, physical, chemical and biological characteristics.

Helical spring template fabrication of cell‐laden microfluidic hydrogels for tissue engineering

Cell-laden microfluidic hydrogels find great potential applications in microfluidics, tissue engineering, and drug delivery, due to their ability to control mass transport and cell microenvironment. A variety of methods have been developed to fabricate hydrogels with microfluidic channels, such as molding, bioprinting, and photopatterning. However, the relatively simple structure available and the specific equipment required limit their broad applications in tissue engineering. Here, we developed a simple method to fabricate microfluidic hydrogels with helical microchannels based on a helical spring template. Results from both experimental investigation and numerical modeling revealed a significant enhancement on the perfusion ability and cell viability of helical microfluidic hydrogels compared to those with straight microchannels. The feasibility of such a helical spring template method was also demonstrated for microfluidic hydrogels with complex three-dimensional channel networks such as branched helical microchannels. The method presented here could potentially facilitate the development of vascular tissue engineering and cell microenvironment engineering.

3D thermoplastic elastomer microfluidic devices for biological probe immobilization

Microfluidics has emerged as a valuable tool for the high-resolution patterning of biological probes on solid supports. Yet, its widespread adoption as a universal biological immobilization tool is still limited by several technical challenges, particularly for the patterning of isolated spots using three-dimensional (3D) channel networks. A key limitation arises from the difficulties to adapt the techniques and materials typically used in prototyping to low-cost mass-production. In this paper, we present the fabrication of thin thermoplastic elastomer membranes with microscopic through-holes using a hot-embossing process that is compatible with high-throughput manufacturing. The membranes provide the basis for the fabrication of highly integrated 3D microfluidic devices with a footprint of only 1 × 1 cm(2). When placed on a solid support, the device allows for the immobilization of up to 96 different probes in the form of a 10 × 10 array comprising isolated spots of 50 × 50 μm(2). The design of the channel network is optimized using 3D simulations based on the Lattice-Boltzmann method to promote capillary action as the sole force distributing the liquid in the device. Finally, we demonstrate the patterning of DNA and protein arrays on hard thermoplastic substrates yielding spots of excellent definition that prove to be highly specific in subsequent hybridization experiments.

Integration in a multilayer microfluidic chip of 8 parallel cell sorters with flow control by sol–gel transition of thermoreversible gelation polymer

Microfluidic systems have significant implications in the field of cell separation since they could provide platforms with inexpensive, disposable and sterile structures. Here, we present a novel strategy to integrate microfluidic sorters into a single chip for high throughput sorting. Our parallel sorter consists of a microfluidic chip with a three-dimensional channel network that utilizes flow switching by a heat-induced sol-gel transition of thermoreversible gelation polymer. The 8 parallel sheathed sample flows were realized by injecting sample and buffer solutions into only 2 inlets. The sheathed flows enabled disposal of unwanted sample waste without laser irradiation, and collection of wanted sample upon irradiation. As an application of the sorter, two kinds of fluorescent microspheres were separated with recovery ratio and purity of 70% or 90% at throughputs of about 100 or 20 particles per second, respectively. Next, Escherichia coli cells expressing green fluorescent protein were separated from those expressing DsRed with recovery ratio and purity of 90% at a throughput of about 20 cells per second.

Multi-layer PMMA microfluidic chips with channel networks for liquid sample operation

The emphasis of this paper lies in the fabrications of an eight-layer chip for liquid mixing and a seven-layer chip for liquid sample dilution. In this paper, the microchannels, fabricated by CO 2 laser, constructed three-dimensional serpentine channel networks for liquid sample operation. The eight-layer mixing chip used the “F”-shape mixing units to achieve splitting and recombination mixing. Furthermore, mixing was enhanced by chaotic flow induced by three-dimensional serpentine channel path. The seven-layer dilution chip created eight diluted fluid streams mixed in same volumetric proportions. Prior to thermal bonding, the polymethylmethacrylate (PMMA) substrates were treated by oxygen plasma to improve their surface properties. The increased surface properties served to reduce thermal bonding temperature and pressure, which minimized the deformation of microchannel. The mixing and diluting experiments showed high levels of mixing and diluting performances were obtained with the chips.

A multi-sensor biological monitoring module built up in LTCC-technology

Low temperature co-fired ceramic (LTCC) technology was originally developed for the realization of multilayer circuits of high reliability. It was recognized that LTCC-technology is a valuable development in thick film technology which launches new application areas as it becomes evident that complex three-dimensional structures can be easily realized. Aspects of the realization of a sophisticated biological monitoring module comprising a three-dimensional network of channels and cavities is demonstrated.

Mechanical and Chemical Protection of a Wired Enzyme Oxygen Cathode by a Cubic Phase Lyotropic Liquid Crystal

When implanted in animals, enzyme-containing battery electrodes, biofuel cell electrodes, and biosensors are often damaged by components of the biological environment. An O2 cathode, superior to the classical platinum cathode, which would be implanted, as part of a caseless physiological pH miniature Zn-O2 battery or as part of a caseless and membraneless miniature glucose-O2 biofuel cell, is rapidly damaged by serum urate at its operating potential. The cathode is made by electrically connecting, or wiring, reaction centers of bilirubin oxidase to carbon with an electron-conducting redox hydrogel. In the physiological pH 7.3 electrolyte battery or biofuel cell, the O2 cathode should operate at, or positive of, 0.3 V (Ag/AgCl), where the urate anion, a common serum component, is electrooxidized. Because an unidentified urate electrooxidation intermediate, formed in the presence of O2, damages the wired bilirubin oxidase electrocatalyst, urate must be excluded from the cathode. Unlike O2, which permeates through both the lipid and the aqueous interconnected networks of cubic-phase lyotropic liquid crystals, urate permeates only through their continuous three-dimensional aqueous channel networks. The aqueous channels have well-defined diameters of approximately 5 nm in the monoolein/water cubic-phase liquid crystal. Through tailoring the wall charge of the aqueous channels, the anion/cation permeability ratio can be modulated. Thus, doping the monoolein of the monoolein/water liquid crystal with 1,2-dioleoyl-sn-glycero-3-phosphate makes the aqueous channel walls anionic and reduces the urate permeation in the liquid crystal. As a result, the ratio of the urate electrooxidation current to the O2 electroreduction current is reduced from 1:3 to 1:100 for 5-mm O2 cathodes rotating at 1000 rpm. Doping with 1,2-dioleoyl-sn-glycero-3-phosphate also increases the shear strength of the cubic-phase monoolein/water lyotropic liquid crystal. While the undoped liquid crystal is promptly damaged at the 0.1 N m-2 average shear stress generated by rotating the 5-mm-diameter disk cathode at 1000 rpm in a physiological aqueous solution, the 10 mol % 1,2-dioleoyl-sn-glycero-3-phosphate-doped film remains intact. The mechanical strengthening of the lyotropic liquid crystal by the two-tailed 1,2-dioleoyl-sn-glycero-3-phosphate is attributed to cross-linking hydrophobic bonds (i.e., bonds resulting of the increase in entropy upon the freeing of the translation and rotation of multiple water molecules), which is analogous to the strengthening of polymer-based plastic materials by cross-linking through covalent bonds.

Development of a multi-layer microelectrofluidic platform

We report on the development of process capabilities for a polymer-based, multi-layer microelectrofluidic platform, namely: the hot embossing process, metallization on polymer and polymer bonding. Hot embossing experiments were conducted to look at the effects of load applied, embossing temperature and embossing time on the fidelity of line arrays representing micro channels. The results revealed that the embossing temperature was a more sensitive parameter than the others due to its large effect on the polymer material’s viscoelastic properties. Dynamic mechanical analysis (DMA) conducted on polymethyl methacrylate (PMMA) revealed a steep glass transition over a 20°C range, with the material losing more than 95% of its storage modulus. The data explained the hot embossing results, which showed large changes in the embossed channel dimensions when the temperature was within the glass transition range. It was demonstrated that the micro-printing of silver epoxy was a possible low-cost technique in the mass production of disposable lab chips. An interconnecting, three-dimensional network of electrical traces was fabricated, as well as a microfluidic device with interconnecting, three-dimensional network of micro channels.

Magnetic resonance imaging of chemical waves in porous media

Magnetic resonance imaging (MRI) provides a powerful tool for the investigation of chemical structures in optically opaque porous media, in which chemical concentration gradients can be visualized, and diffusion and flow properties are simultaneously determined. In this paper we give an overview of the MRI technique and review theory and experiments on the formation of chemical waves in a tubular packed bed reactor upon the addition of a nonlinear chemical reaction. MR images are presented of reaction-diffusion waves propagating in the three-dimensional (3D) network of channels in the reactor, and the 3D structure of stationary concentration patterns formed via the flow-distributed oscillation mechanism is demonstrated to reflect the local hydrodynamics in the packed bed. Possible future directions regarding the influence of heterogeneities on transport and reaction are discussed.

Synthesis, Characterization, and Crystal Engineering of [NiII(1,2-Diaminocyclohexane)3](N3)Cl: Three-Dimensional Framework by Hexafurcated N–H ⋅s Cl− Hydrogen Bonds

Synthesis, characterization, and crystal engineering of a tris chelate compound, [NiIIL3](N3)Cl (1), (L = diequatorial trans-1,2-diaminocyclohexane) have been described. The compound crystallizes in the cubic P4332 space group with a = 13.859(12) A and Z = 4. In this structure, the azide anion is highly disordered. Each chloride in 1 interacts with six amine hydrogens and is surrounded by three mononuclear cations, each of which, in turn, are linked with three chlorides to form a three-dimensional channel network. This is the first report of hexafurcated (acceptor) N–H ⋅s Cl− hydrogen bonds in metalloorganic systems and the first report of the three-dimensional framework resulted basically due to the multifurcated acceptor nature of the halide anion.