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Live-cell microscopy is crucial for biomedical studies and clinical tests. The technique is, however, limited to few laboratories due to its high cost and bulky size of the necessary culture equipment. In this study, we propose a portable microfluidic-cell-culture system, which is merely 15   cm × 11   cm × 9   cm in dimension, powered by a conventional alkali battery and costs less than USD 20. For long-term cell culture, a fresh culture medium exposed to 5% CO2 is programmed to be delivered to the culture chamber at defined time intervals. The 37 ° C culture temperature is maintained by timely electrifying the ITO glass slide underneath the culture chamber. Our results demonstrate that 3T3 fibroblasts, HepG2 cells, MB-231 cells and tumor spheroids can be well-maintained for more than 48 h on top of the microscope stage and show physical characters (e.g., morphology and mobility) and growth rate on par with the commercial stage-top incubator and the widely adopted CO2 incubator. The proposed portable cell culture device is, therefore, suitable for simple live-cell studies in the lab and cell experiments in the field when samples cannot be shipped. [ABSTRACT FROM AUTHOR]

Stripe arrays of poly(methacrylic acid) (PMAA) brushes were grafted using a photoresist template to fabricate one-dimensional photonic crystal (OPCs). The as-prepared samples were first bound with protein G to immobilize and orient tails of the antibody of Pa (abY). A fluidic diffraction chip based on the abY-tailed PMMA OPC was fabricated to examine the ability of Pa detection from whole blood specimen. Pa was attached to the abY-tailed PMMA OPC after flowing through the fluidic chip, which changed the diffraction intensity. A laser beam was employed to analyze the reflective signals of OPCs at an incident angle of 45°. The abY-tailed PMAA OPC possessed an optical feature with a characteristic diffraction effect such that the projection of the laser beam on the plane of the OPC chip was parallel to the strips in SII configurations, whereas they were perpendicular in ST configurations. The degree of the diffraction intensity exhibited a linear response to Pa at concentrations from 102 to 107 CFU mL−1, and the limit of detection was 100 CFU mL−1, indicating the excellent sensitivity in Pa-spiked whole blood samples. The proposed platform provides a rapid, label-free method for Pa detection to improve the administration of antibiotics in a timely manner.

Live-cell microscopy is crucial for biomedical studies and clinical tests. The technique is, however, limited to few laboratories due to its high cost and bulky size of the necessary culture equipment. In this study, we propose a portable microfluidic-cell-culture system, which is merely 15 cm×11 cm×9 cm in dimension, powered by a conventional alkali battery and costs less than USD 20. For long-term cell culture, a fresh culture medium exposed to 5% CO2 is programmed to be delivered to the culture chamber at defined time intervals. The 37 °C culture temperature is maintained by timely electrifying the ITO glass slide underneath the culture chamber. Our results demonstrate that 3T3 fibroblasts, HepG2 cells, MB-231 cells and tumor spheroids can be well-maintained for more than 48 h on top of the microscope stage and show physical characters (e.g., morphology and mobility) and growth rate on par with the commercial stage-top incubator and the widely adopted CO2 incubator. The proposed portable cell culture device is, therefore, suitable for simple live-cell studies in the lab and cell experiments in the field when samples cannot be shipped.

ABSTRACT Many patients with severe infections receive inappropriate empirical treatment, and rapid detection of bacterial antibiotic susceptibility can improve clinical outcome and reduce mortality. To this end, we have developed a multiplex fluidic chip for rapid phenotypic antibiotic susceptibility testing of bacteria. A total of 21 clinical isolates of Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus were acquired from the EUCAST Development Laboratory and tested against amikacin, ceftazidime, and meropenem (Gram-negative bacteria) or gentamicin, ofloxacin, and tetracycline (Gram-positive bacteria). The bacterial samples were mixed with agarose and loaded in an array of growth chambers in the chip where bacterial microcolony growth was monitored over time using automated image analysis. MIC values were automatically obtained by tracking the growth rates of individual microcolonies in different regions of antibiotic gradients. Stable MIC values were obtained within 2 to 4 h, and the results showed categorical agreement with reference MIC values as determined by broth microdilution in 86% of the cases. IMPORTANCE Prompt and effective antimicrobial therapy is crucial for the management of patients with severe bacterial infections but is becoming increasingly difficult to provide due to emerging antibiotic resistance. The traditional methods for antibiotic susceptibility testing (AST) used in most clinical laboratories are reliable but slow with turnaround times of 2 to 3 days, which necessitates the use of empirical therapy with broad-spectrum antibiotics. There is a great need for fast and reliable AST methods that enable starting targeted treatment within a few hours to improve patient outcome and reduce the overuse of broad-spectrum antibiotics. The multiplex fluidic chip for phenotypic AST described in the present study may enable data on antimicrobial resistance within 2 to 4 h, allowing for an early initiation of appropriate antibiotic therapy.

Immunomagnetic separation has been widely used for the separation and concentration of foodborne pathogens from complex food samples, however it can only handle a small volume of samples. In this paper, we presented a novel fluidic device for the specific and efficient separation and concentration of salmonella typhimurium using self-assembled magnetic nanoparticle chains. The laminated sawtooth-shaped iron foils were first mounted in the 3D-printed matrix and magnetized by a strong magnet to generate dot-array high gradient magnetic fields in the fluidic channel, which was simulated using COMSOL (5.3a, Burlington, MA, USA). Then, magnetic nanoparticles with a diameter of 150 nm, which were modified with the anti-salmonella polyclonal antibodies, were injected into the channel, and the magnetic nanoparticle chains were vertically formed at the dots and verified using a fluorescence inverted microscope. Finally, the bacterial sample was continuous-flow injected, and the target bacteria could be captured by the antibodies on the chains, followed by gold standard culture plating to determine the amount of the target bacteria. Under the optimal conditions, the target bacteria could be separated with a separation efficiency of 80% in 45 min. This fluidic device could be further improved using thinner sawtooth-shaped iron foils and stronger magnets to obtain a better dot-array magnetic field with larger magnetic intensity and denser dot distribution, and has the potential to be integrated with the existing biological assays for rapid and sensitive detection of foodborne bacteria.

We describe a novel stacked split-ring type microwave (MW) resonator that is integrated into a 10 mm by 10 mm sized microfluidic chip. A straightforward and scalable batch fabrication process renders the chip suitable for single-use applications. The resonator volume can be conveniently loaded with liquid sample via microfluidic channels patterned into the mid layer of the chip. The proposed MW resonator offers an alternative solution for compact in-field measurements, such as low-field magnetic resonance (MR) experiments requiring convenient sample exchange. A microstrip line was used to inductively couple MWs into the resonator. We characterised the proposed resonator topology by electromagnetic (EM) field simulations, a field perturbation method, as well as by return loss measurements. Electron paramagnetic resonance (EPR) spectra at X-band frequencies were recorded, revealing an electron-spin sensitivity of 3.7 · 10 11 spins · Hz - 1 / 2 G - 1 for a single EPR transition. Preliminary time-resolved EPR experiments on light-induced triplet states in pentacene were performed to estimate the MW conversion efficiency of the resonator. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes a piezostack actuated peristaltic micropump featuring a normally-closed function up to pressures of 100 kPa, when the electric power is off. The design is based on a modular setup with a re-usable actuator unit and a low-cost disposable fluidic chip that can easily be exchanged after contamination or use. Pump rates up to 40 μl/min at 28.6 Hz are demonstrated with water. The flow rates are backpressure independent up to 7 kPa, with a maximum backpressure of 45 kPa at 140 V. Also liquids with high viscosities up to 46 mPas are pumped successfully. [Copyright &y& Elsevier]

A reactant volume self-controlled micro-device was presented and applied to the flow injection chemiluminescence (CL) for determination of cyanide in whole blood. A mini distiller was fabricated for cyanide extraction from the blood samples with the extraction efficiencies of cyanide ≥98%. A fluidic control platform with air driving was fabricated. The described system showed the features of easy fabrication, undiluted sample injection, safe analysis operation, and suitability for automatic cyanide analysis. The calibration curve showed linearity in the cyanide concentration range of 5.0×10-7 to 5.0×10-5 mol l-1 with the detection limits (3σ) of 2.3×10-7 mol l-1. CL peak-height precision was 1.9% R.S.D. (n=11) at the 1.0×10-6 mol l-1 cyanide level. The new devices were applied to the analysis of cyanide in rabbit whole blood samples and the results agreed well with those obtained from official method. [Copyright &y& Elsevier]

A mircrofluidic chip, based on using an air stream for fluidic controlling and coupled with chemiluminescence (CL) detection, was presented. The reported design promised a simple, low cost chip fabrication, and an easy operation. With each assay time less than 3 min, the described microfluidic chip was applied in determination of iron(II) content in nature water and total iron content in whole blood. Experiment results showed the potential for a multitude of applications of the presented chip. The calibration graph of chemiluminescent intensity (ICL) vs. iron(II) concentration was linear in the range 1.0 × 10-6-5.0 × 10-5 mol L-1, and the detection limit (DL) was 3.0 × 10-7 mol L-1 (3σ). [ABSTRACT FROM AUTHOR]

Paper-based biosensor is one of the most commonly used platforms for point-of-care testing (POCT). Among these platforms, microfluidic paper-based analytical devices (μPADs) have the most versatile designs due to the different hydrophobic barrier patterns and layers of the devices. In addition, μPADs can also be used in combination with other biosensor platforms to improve the performance of the device. Simple and convenient methods for fabricating low-cost and design-adjustable hydrophobic barriers on paper are one of the most challenging aspects for creating μPADs. This work demonstrated a simple technique for using the common polylactic acid (PLA) filament and wax filament to create hydrophobic barriers on paper for μPADs using a commercialized 3D printer. As a proof of concept, the papers with 3D printed PLA barrier were used in combination with a fluidic chip in a prototype biosensor, in which the barrier paper housed four cell-free reactions and the fluidic chip achieved sample delivery to the reactions in the device. Our designed prototype was capable of discriminating dengue virus serotypes based on small nucleotide sequence differences. The proposed combination of 3D-printed barrier paper and fluidic chip provides a versatile platform for rapid prototyping of POCT with possible compatibility with various detection systems. [Display omitted] • 3D printing PLA and wax filaments for creating hydrophobic barriers on paper. • New design for non-immobilized reactions into a prototype biosensor platform. • Prototype biosensor for POCT and discriminating DENV serotypes. [ABSTRACT FROM AUTHOR]

• A near-infrared imaging method is used for temperature measurement.. • Induction heating of micro-magnetic particle layers is performed in a fluidic channel. • Temperature images of water near the layers are acquired under different heating conditions. • The heat generation rates of the layers are determined. This paper presents an experimental method for measuring the water temperature near micro-magnetic particle (MMP) layers in a fluidic channel under induction heating. This method is based on the temperature dependence of the spectrum of the ν 1 + ν 3 absorption band of water in the near-infrared (NIR) region. The absorbance images at the wavelength of 1412 nm, which is the most temperature-sensitive wavelength in the band, were obtained through a U-shaped channel with an optical path length of 1 mm using a narrow-bandpass filter and an NIR camera. An MMP layer was formed on the inner surface of the channel by an external strong permanent magnet and then heated inductively by applying a 760-kHz magnetic field. The temperature distribution of water was found to depend on the heating time, heating power level, and MMP layer thickness (0.5, 0.6, and 1.0 mm). The maximum increase in temperature near the MMP layer was approximately 5 °C, and the temperature resolution was 0.2 °C. A numerical simulation was used to verify the measured temperature profiles then apply the residual fitting method to determine the heat generation rates (HGRs) of the MMPs. The HGRs were independent of the heating time, and varied consistently with the heating power level. This method is useful for the quantitative understanding and control of temperature fields in applications that use MMPs for chemical reactions and cell/tissue therapy. [ABSTRACT FROM AUTHOR]

Immunomagnetic separation has been widely used for the separation and concentration of foodborne pathogens from complex food samples, however it can only handle a small volume of samples. In this paper, we presented a novel fluidic device for the specific and efficient separation and concentration of salmonellatyphimurium using self-assembled magnetic nanoparticle chains. The laminated sawtooth-shaped iron foils were first mounted in the 3D-printed matrix and magnetized by a strong magnet to generate dot-array high gradient magnetic fields in the fluidic channel, which was simulated using COMSOL (5.3a, Burlington, MA, USA). Then, magnetic nanoparticles with a diameter of 150 nm, which were modified with the anti-salmonella polyclonal antibodies, were injected into the channel, and the magnetic nanoparticle chains were vertically formed at the dots and verified using a fluorescence inverted microscope. Finally, the bacterial sample was continuous-flow injected, and the target bacteria could be captured by the antibodies on the chains, followed by gold standard culture plating to determine the amount of the target bacteria. Under the optimal conditions, the target bacteria could be separated with a separation efficiency of 80% in 45 min. This fluidic device could be further improved using thinner sawtooth-shaped iron foils and stronger magnets to obtain a better dot-array magnetic field with larger magnetic intensity and denser dot distribution, and has the potential to be integrated with the existing biological assays for rapid and sensitive detection of foodborne bacteria. [ABSTRACT FROM AUTHOR]