Tailoring porous media for controllable capillary flow

Capillary efficiency study in leaf vein morphology inspired channels

Inspired by the capillary transport function of plant leaf veins, this study proposes three typical leaf vein features by observing a large number of leaves, including wedge shape, branch asymmetry, as well as hierarchical arrangement, and investigates their capillary transport mechanism. Not only a preliminary theoretical analysis of capillary flow in the bio-inspired channels was carried out, but the COMSOL Multiphysics simulation software was also used to simulate gas-liquid two-phase flow in biomimetic channels. The results reveal the efficient transport mechanism of the leaf vein inspired structure and provide insight into the design of capillary transmission channels.

The growth of capillary networks by branching for maximum fluid access

Here we document the deterministic evolution of capillary networks that morph by connecting more and more branches to water sources. The network grows with the objective of extracting in steady state higher and higher liquid flow rates. Growth happens through the generation of tree-shaped structures and the geometrical configuration of the dendritic network evolves as the number of connected sources increases. We present a novel methodology to generate capillary architectures and show how the evolution of the network leads to pump higher volumetric flow rates by capillary suction. The results suggest that networks generated within a plane lead to higher flow rates than networks generated within a three-dimensional domain, for the same volume of fluid.

Screen Printed Particle-Based Microfluidics: Optimization and Exemplary Application for Heavy Metals Analysis

In this work, a screen-printing method was developed to create porous particle-based materials as layers with specifically designed shape to produce microfluidics systems. Among several tested binding agents, xanthan gum was found to be an excellent choice for a printing mixture thickener as well as a durable binder for the resulting material. In addition to demonstrating control over the shape of the printed microfluidics chips, control over material thickness, wetting characteristics and general method accuracy were also investigated. The applicability of the introduced method was further demonstrated with a development of an exemplary microfluidics chip for quantitative detection of Fe (III), Ni (II), Cu (II), Cd (II), and Pb (II) from a mixed sample at millimolar levels. The novel approaches demonstrated in this article offer new perspective into creating multiplexed on-site chemical analysis tests.

Impact of masking hypomineralization opacities in anterior teeth on the esthetic perception of children and parents: A randomized controlled clinical trial

OBJECTIVES

The aim of this study was to evaluate the impact of treating demarcated opacities in anterior teeth on the esthetic perception of children and their parents. Additionally, the masking effect was evaluated quantitively and qualitatively.

METHODS

Thirty-nine patients, 8-18 years-old, presenting white-creamy opacity in permanent incisors were randomly allocated to test or control group. Test received resin infiltration and control received a placebo. The questionnaire Child's and Parent's Questionnaire about Teeth Appearance was used. The masking effect was quantitatively analyzed using the Lab System to calculate the color difference (ΔE) between the opacity and the surrounding enamel in Photoshop. Fisher's, Chi-square, Wilcoxon, Mann-Whitney tests and Spearman's correlation were applied to data analysis.

RESULTS

In the test group, a significant impact on physical and psychological domains in parents' and in social domain in parents' and children's perception was observed (p<0.05). Significant difference in ΔE between test and control groups was seen from 15 min of application onwards (p<0.05). After treatment, the mean ΔE was 4.07 (SD=3.07) in the test and 7.35 (SD=3.54) in the control group (p<0.01). One month later, the mean ΔE was 4.22 (SD=2.96) in the test and 6.06 (SD=2.52) in the control group (p<0.01). Total masking was seen only in the test group (p<0.01).

CONCLUSION

Aesthetic treatment of hypomineralization opacities in anterior teeth with resin infiltration impacted positively on parents and children. Resin infiltration reduced the color difference between opacities and sound enamel significantly after an application time of at least fifteen minutes.

CLINICAL SIGNIFICANCE

Opacities in anterior teeth impact the self-image of children and parents negatively. This study demonstrated that 15 min resin infiltration can mask opacities in permanent incisors and recover social wellbeing. This minimally invasive approach can be offered to MIH children who report dissatisfaction with their incisors.

Rapid and accurate nanoelectrokinetic diagnosis of drug-resistant bacteria

Increased antimicrobial resistance presents a major threat to public health, and it is a global health problem due to the rapid globalization and transmission of infectious diseases. However, fast and precise diagnosis tool is lacking, and inappropriate antibiotic prescription leads to the unforeseen production of drug-resistant bacteria. Here, we report a Rapid and Accurate Nanoelectrokinetic Diagnostic System (RANDx) for detecting drug-resistant bacteria, which cause a common infectious disease called Urinary Tract Infection (UTI), within 7 min. We develop nanoelectrokinetic paper-based analytic device (NEK-PAD) as a sample prep module of RANDx and obtain >100-fold post-wetting preconcentration by balancing between ion concentration polarization (ICP) and radial imbibition for a constant flow rate. Simultaneously with preconcentration, our cathodic nanochannel design enables NEK-PAD to extract drug-resistant enzymes without denaturation and accelerate enzyme-linked reactions under electrical spontaneous heating at approximately 37 °C. Finally, using a cell phone camera, we detect label-free drug-resistant bacteria as low as 10⁴ cfu/mL, which is higher than clinically required threshold (>10⁵ cfu/mL) by enhancing 1000 times of the limit of detection (LOD) of colorimetric nitrocefin assay. We believe that the RANDx will be an innovative precision medicine tool for UTI and other infectious diseases in limited remote settings.

A simple strategy for signal enhancement in lateral flow assays using superabsorbent polymers

To enhance the sensitivity of lateral flow assays (LFAs), a simple strategy is proposed using a nitrocellulose membrane modified with a superabsorbent polymer (SAP). SAP was incorporated into a nitrocellulose membrane for the flow control of detection probes. When absorbing aqueous solutions, SAP promoted the formation of biomolecule complexes to achieve up to a tenfold sensitivity improvement for the detection of human IgG. The assay time was optimized experimentally and numerically to within 20 min using this strategy. Moreover, fluid saturation in LFAs modified with SAP was mathematically simulated to better understand the underlying process, and molecular dynamics simulations were carried out to determine the effect of SAP. The proposed design was also applied to samples spiked with human immunoglobulin-depleted serum to test its applicability. The strategy presented is unique in that it preserves the characteristics of conventional LFAs, as it minimizes user intervention and is simple to manufacture at scale.