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Multiplexed droplet digital recombinase polymerase amplification (MddRPA) for detection of pandemic diseases.

The precise manipulation of the neural stem cell (NSC)-derived neural differentiation is still challenging, and there is a technological barrier to regulate the axonal regeneration in a controlled manner. Here, we developed a microfluidic chip integrated with a microelectrode array as an axonal guidance platform. The microfluidic electrode array chip consisted of two compartments and a bridge microchannel that could isolate and guide the axons. We demonstrated that the NSCs were largely differentiated into neural cells as the electric field was applied to the microfluidic electrode array chip. We also confirmed the synergistic effects of the electrical stimulation (ES) and neurotrophic factor (NF) on axonal outgrowth. This microfluidic electrode array chip can serve as a central nervous system (CNS) model for axonal injury and regeneration. Therefore, it could be a potentially powerful tool for an

For rapid detection of the COVID-19 infection, the digital polymerase chain reaction (dPCR) with higher sensitivity and specificity has been presented as a promising method of point-of-care testing (POCT). Unlike the conventional real-time PCR (qPCR), the dPCR system allows absolute quantification of the target DNA without a calibration curve. Although a number of dPCR systems have previously been reported, most of these previous assays lack multiplexing capabilities. As different variants of COVID-19 have rapidly emerged, there is an urgent need for highly specific multiplexed detection systems. Additionally, the advances in the Internet of Things (IoT) technology have enabled the onsite detection of infectious diseases. Here, we present an IoT-integrated multiplexed dPCR (IM-dPCR) system involving sample compartmentalization, DNA amplification, fluorescence imaging, and quantitative analysis. This IM-dPCR system comprises three modules: a plasmonic heating-based thermal cycler, a multi-color fluorescence imaging set-up, and a firmware control module. Combined with a custom-developed smartphone application built on an IoT platform, the IM-dPCR system enabled automatic processing, data collection, and cloud storage. Using a self-priming microfluidic chip, 9 RNA groups (

We developed a microfluidic gradient device to utilize as a drug screening system with human induced pluripotent stem cell (hiPSC)-derived motoneurons. The microfluidic channel was asymmetrically designed to generate the concentration gradients and a micropillar array was used to trap and culture the motoneuron spheroids containing motoneurons for 9 days. We optimized the concentration gradients in the microfluidic device using a computational fluid dynamics (CFD) model. We also observed that the motoneuron spheroid-derived neurite network was generated in response to the concentration gradients of riluzole in the microfluidic device. Therefore, this microfluidic gradient device could be useful for screening of various drugs for neurological disease applications.

A miniaturized polymerase chain reaction (PCR) system is not only important for medical applications in remote areas of developing countries, but also important for testing at ports of entry during global epidemics, such as the current outbreak of the coronavirus. Although there is a large number of PCR sensor systems available for this purpose, there is still a lack of portable digital PCR (dPCR) heating systems. Here, we first demonstrated a portable plasmonic heating-based dPCR system. The device has total dimensions of 9.7 × 5.6 × 4.1 cm and a total power consumption of 4.5 W, allowing for up to 25 dPCR experiments to be conducted on a single charge of a 20 000 mAh external battery. The dPCR system has a maximum heating rate of 10.7 °C s−1 and maximum cooling rate of 8 °C s−1. Target DNA concentrations in the range from 101 ± 1.4 copies per μL to 260 000 ± 20 000 copies per μL could be detected using a poly(dimethylsiloxane) (PDMS) microwell membrane with 22 080 well arrays (20 μm diameter). Furthermore, the heating system was demonstrated using a mass producible poly(methyl methacrylate) PMMA microwell array with 8100 microwell arrays (80 μm diameter). The PMMA microwell array could detect a concentration from 12 ± 0.7 copies per μL to 25 889 ± 737 copies per μL.

The research of fungi is of great importance in a number of fields, such as environmental and healthcare studies. While there are a large number of optical and molecular methods available for characterization and identification of fungi and their spores, their isolation is still conducted using slow and labor-intensive methods. Here, we develop a microfluidic device for the continuous separation of fungal spores from other eukaryotic cells. The spores were separated through the microfluidic device by expanding pinched flow fractionation (PFF) containing the spores, achieving a spatial separation perpendicular to the flow direction according to the spore size. Further branch flow fractionation (BFF) and co-flow of a Newtonian and viscoelastic fluid were used to enhance the separation performance. Using this microfluidic device, we demonstrated the separation of two different types of fungal spores and further separation of fungal spores from eukaryotic cells with a separation efficiency of above 90%. Compared to the existing conventional methods, our microfluidic flow focusing device requires little manual handling and uses small amounts of samples without any pre-treatment steps of the samples.

The invention of the polymerase chain reaction (PCR) has caused a revolution in molecular biology, giving access to a method of amplifying deoxyribonucleic acid (DNA) molecules across several orders of magnitude. Since the first application of PCR in a microfluidic device was developed in 1998, an increasing number of researchers have continued the development of microfluidic PCR systems. In this review, we introduce recent developments in microfluidic-based space and time domain devices as well as discuss various designs integrated with multiple functions for sample preparation and detection. The development of isothermal nucleic acid amplification and digital PCR microfluidic devices within the last five years is also highlighted. Furthermore, we introduce various commercial microfluidic PCR devices.

Microfluidic technologies are emerging as an enabling tool for various applications in tissue engineering and cell biology. One emerging use of microfluidic systems is the generation of shape-controlled hydrogels (i.e., microfibers, microparticles, and hydrogel building blocks) for various biological applications. Furthermore, the microfluidic fabrication of cell-laden hydrogels is of great benefit for creating artificial scaffolds. In this paper, we review the current development of microfluidic-based fabrication techniques for the creation of fibers, particles, and cell-laden hydrogels. We also highlight their emerging applications in tissue engineering and regenerative medicine.

The ability to rapidly generate concentration gradients of diffusible molecules has important applications in many chemical and biological studies. Here we established spatially and temporally controllable concentration gradients of molecules (i.e. proteins or toxins) in a portable microfluidic device in an easy and rapid manner. The formation of the concentration gradients was initiated by a passive-pump-induced forward flow and further optimized during an evaporation-induced backward flow. The centimeter-length gradients along the microfluidic channel were shown to be spatially and temporally controlled by the backward flow. The gradient profile was stabilized by stopping the flow. Computational simulations of this dynamic process illustrated the combined effects of convection and diffusion on the gradient generation, and fit well with the experimental data. To demonstrate the applications of this methodology, a stabilized concentration gradient of a cardiac toxin, Alpha-cypermethrin, along the microchannel was used to test the response of HL-1 cardiac cells in the micro-device, which correlated with toxicity data obtained from multi-well plates. The approach presented here may be useful for many biological and chemical processes that require rapid generation of long-range gradient in a portable microfluidic device.

We report recent progress in the development of surface-enhanced Raman scattering (SERS)-based optofluidic platforms for the fast and sensitive detection of chemical and biological analytes. In the current context, a SERS-based optofluidic platform is defined as an integrated analytical device composed of a microfluidic element and a sensitive Raman spectrometer. Optofluidic devices for SERS detection normally involve nanocolloid-based microfluidic systems or metal nanostructure-embedded microfluidic systems. In the current review, recent advances in both approaches are surveyed and assessed. Additionally, integrated real-time sensing systems that combine portable Raman spectrometers with microfluidic devices are also reviewed. Such real-time sensing systems have significant utility in environmental monitoring, forensic science and homeland defense applications.

This paper describes a microfluidic multi-injector (MMI) that can generate temporal and spatial concentration gradients of soluble molecules. Compared to conventional glass micropipette-based methods that generate a single gradient, the MMI exploits microfluidic integration and actuation of multiple pulsatile injectors to generate arbitrary overlapping gradients that have not previously been possible. The MMI device is fabricated in poly(dimethylsiloxane) (PDMS) using multi-layer soft lithography and consists of fluidic channels and control channels with pneumatically actuated on-chip barrier valves. Repetitive actuation of on-chip valves control pulsatile release of solution that establishes microscopic chemical gradients around the orifice. The volume of solution released per actuation cycle ranged from 30 picolitres to several hundred picolitres and increased linearly with the duration of valve opening. The shape of the measured gradient profile agreed closely with the simulated diffusion profile from a point source. Steady state gradient profiles could be attained within 10 minutes, or less with an optimized pulse sequence. Overlapping gradients from 2 injectors were generated and characterized to highlight the advantages of MMI over conventional micropipette assays. The MMI platform should be useful for a wide range of basic and applied studies on chemotaxis and axon guidance.