Search Results (258)

Digital PCR, as a nucleic acid absolute quantification method at the single-molecule level, has been widely applied in early cancer screening, single-cell analysis, and other biomedical fields. However, existing digital PCR methods still suffer from high costs, complex operations, and low detection dynamic range, which limit their applications. In the study, we developed a microfluidic chip-based digital PCR with a high-density vertical structure using PDMS (polydimethylsiloxane) flexible material. The chip features a three-layer structure of glass–PDMS–glass, with the PDMS structural layer containing 30,000 reaction chambers, each with a volume of 0.713 nL. This vertical-structured chip can increase the total volume and the total number of chambers by 50% without changing the chip area and chamber volume, thereby significantly enhancing dynamic range and sensitivity of the chip detection. This chip is theoretically capable of achieving a nucleic acid detection dynamic range close to 10⁵. Moreover, the digital PCR quantitative detection results of five different concentrations of serially diluted KRAS plasmid DNA templates using this chip also validated the accuracy and reliability of the nucleic acid quantitative detection results. The vertical-structured digital PCR chip, with its simple manufacturing process, uniform and stable sample partitioning, wide detection dynamic range, and low cost, will promote the widespread application of digital PCR. Full article

Laser-induced forward transfer (LIFT) bioprinting enables precise deposition of biological materials for advanced biomedical applications. This study presents a parametric analysis of the donor–receiver distances (1.0, 1.5, 2.0, 2.5, and 3.0 mm) in LIFT bioprinting, investigated through high-speed video and image analysis of 4 × 4 spot arrays. Droplet velocity was quantified and jet trajectory characterized, revealing that increased distances reduced spatial resolution, with significant shape deterioration observed beyond 2.0 mm. Thus, a maximum 2.0 mm donor–receiver gap was determined as optimal for acceptable printing resolution. As an application, a microfluidic device was fabricated using LCD 3D printing with a biocompatible resin and glass-bottomed configuration. The chamber height was matched to the validated 2.0 mm distance, ensuring compatibility with LIFT printing. Computational fluid dynamics simulations were conducted to model fluid flow conditions within the device. Subsequently, LLC cells were successfully printed inside the microfluidic chamber, cultured under continuous flow for 24 h, and demonstrated normal proliferation. This work highlights LIFT bioprinting’s viability and precision for integrating cells within microfluidic platforms, presenting promising potential for organ-on-chip applications and future biomedical advancements. Full article

The detection of proteins plays a key role in disease diagnosis and drug development. For this, we numerically investigated a novel microfluidic motor actuated by an induced-charge electro-osmotic (ICEO) whirling flow. An alternating current–flow field effect transistor is engineered to modulate the profiles of ICEO streaming to stimulate and adjust the whirling flow in the circle microfluidic chamber. Based on this, we studied the distribution of an ICEO whirling flow in the detection chamber by tuning the fixed potential on the gate electrodes by the simulations. Then, we established a fluid–structure interaction model to explore the influence of blade structure parameters on the rotation performance of microfluidic motors. In addition, we investigated the rotation dependence of microfluidic motors on the potential drop between two driving electrodes and fixed potential on the gate electrodes. Next, we numerically explored the capability of these microfluidic motors for the detection of low-abundance proteins. Finally, we studied the regulating effect of potential drops between the driving electrodes on the detection performance of microfluidic motors by numerical simulations. Microfluidic motors actuated by an ICEO whirling flow hold good potential in environmental monitoring and disease diagnosis for the outstanding advantages of flexible controllability, a simple structure, and gentle work condition. Full article

The possibility of tightly controlling the cellular microenvironment within microfluidic devices represents an important step toward precision analysis of cellular phenotypes in vitro. Microfluidic platforms that allow both long-term mammalian cell culture and dynamic modulation of the culture environment can support quantitative studies of cells’ responses to drugs. Here, we report the design and testing of a novel microfluidic device of simple production (single Polydimethylsiloxane layer), which integrates a micromixer with vacuum-assisted cell loading for long-term mammalian cell culture and dynamic mixing of four different culture media. Finite element modeling was used to predict flow rates and device dimensions to achieve diffusion-based fluid mixing. The device showed efficient mixing and dynamic exchange of media in the cell-trapping chambers, and viability of mammalian cells cultured for long-term in the device. This work represents the first attempt to integrate single-layer microfluidic mixing devices with vacuum-assisted cell-loading systems for mammalian cell culture and dynamic stimulation. Full article

This study presents an innovative wedge-shaped inlet weir-type microfluidic chip designed to address common issues of clogging and inefficiency in microfiltration processes. Driven solely by centrifugal force, the chip integrates a crossflow separation mechanism and enables selective droplet sorting based on size, without the need for external pumps. Fabricated from PMMA, the device features a central elliptical chamber, a wedge-shaped inlet, and spiral microchannels. These structures leverage shear stress and Dean vortices under centrifugal fields to achieve high-throughput separation of droplets with different diameters. Using water-in-oil emulsions as a model system, we systematically investigated the effects of geometric parameters and rotational speed on separation performance. A theoretical model was developed to derive the critical droplet size based on force balance, accounting for centrifugal force, viscous drag, pressure differentials, and surface tension. Experimental results demonstrate that the chip can effectively separate droplets ranging from 0 to 400 μm in diameter at 200 rpm, achieving a sorting efficiency of up to 72% and a separation threshold (cutoff accuracy) of 98.2%. Fluorescence analysis confirmed the absence of cross-contamination during single-chip operation. This work offers a structure-guided, efficient, and contamination-free droplet sorting strategy with broad potential applications in biomedical diagnostics and drug screening. Full article

Peripheral myelination is driven by the intricate interplay between Schwann cells and axons, coordinated through molecular signaling and the structural organization of their shared environment. While the biochemical regulation of this process has been extensively studied, the influence of spatial architecture and mechanical cues remains poorly understood. Here, we use in vitro co-culture models—featuring microfluidic devices and hydrogel-based scaffolds—to explore how extracellular organization, cellular density, and spatial constraints shape Schwann cell behavior. Our results show that (i) pro-myelinating effects triggered by ascorbic acid administration is distally propagated along axons in Schwann cell-DRG co-cultures, (ii) ascorbic acid modulates Neuregulin-1 expression, (iii) a critical threshold of cellular density is required to support proper Schwann cell differentiation and myelin formation, and (iv) spatial confinement promotes myelination in the absence of ascorbic acid. Together, these findings highlight how spatial and structural parameters regulate the cellular and molecular events underlying peripheral myelination, offering new physiologically relevant models of myelination and opening new avenues for peripheral nerve repair strategies. Full article

Microfluidic modulation spectroscopy-infrared (MMS) offers a label-free, high-sensitivity approach for quantifying changes in protein secondary structures under native solution conditions. MMS subtracts the solvent backgrounds from sample signals by alternately flowing proteins and matched buffers through a microfluidic chamber, yielding clear amide I spectra from microliter volumes. In this study, we validated MMS on canonical globular proteins, bovine serum albumin, mCherry, and lysozyme, demonstrating accurate detection and resolution of α-helix, β-sheet, and mixed-fold structures. Applying MMS to the intrinsically disordered protein Tau, we detected environment-driven shifts in transient conformers: both the acidic (pH 2.5) and alkaline (pH 10) conditions increased the turn/unordered structures and decreased the α-helix content relative to the neutral pH, highlighting the charge-mediated destabilization of the labile motifs. Hyperphosphorylation of Tau yielded a modest decrease in the α-helical fraction and an increase in the turn/unordered structures. Comparison of monomeric and aggregated hyperphosphorylated Tau revealed a dramatic gain in β-sheet and a loss in turn/unordered structures upon amyloid fibril formation, confirming MMS’s ability to distinguish disordered monomers from amyloids. These findings establish MMS as a robust platform for detecting protein secondary structures and monitoring aggregation pathways in both folded and disordered systems. The sensitive detection of structural transitions offers opportunities for probing misfolding mechanisms and advancing our understanding of aggregation-related diseases. Full article

Hydroxychloroquine (HCQ), a cornerstone therapeutic agent for autoimmune diseases, requires precise serum concentration monitoring due to its narrow therapeutic window. Current HCQ monitoring methods such as HPLC and LC-MS/MS are sensitive but costly and complex. While electrochemical sensors offer rapid, cost-effective detection, their large chambers and high sample consumption hinder point-of-care use. To address these challenges, we developed a microfluidic electrochemical sensing platform based on a screen-printed carbon electrode (SPCE) modified with a hierarchical nanocomposite of gold nanoparticles (AuNPs), copper-based metal–organic frameworks (Cu-MOFs), and multi-walled carbon nanotubes (MWCNTs). The Cu-MOF provided high porosity and analyte enrichment, MWCNTs established a 3D conductive network to enhance electron transfer, and AuNPs further optimized catalytic activity through localized plasmonic effects. Structural characterization (SEM, XRD, FT-IR) confirmed the successful integration of these components via π-π stacking and metal–carboxylate coordination. Electrochemical analyses (CV, EIS, DPV) revealed exceptional performance, with a wide linear range (0.05–50 μM), a low detection limit (19 nM, S/N = 3), and a rapid response time (<5 min). The sensor exhibited outstanding selectivity against common interferents, high reproducibility (RSD = 3.15%), and long-term stability (98% signal retention after 15 days). By integrating the nanocomposite-modified SPCE into a microfluidic chip, we achieved accurate HCQ detection in 50 μL of serum, with recovery rates of 95.0–103.0%, meeting FDA validation criteria. This portable platform combines the synergistic advantages of nanomaterials with microfluidic miniaturization, offering a robust and practical tool for real-time therapeutic drug monitoring in clinical settings. Full article

As one of the major rice fungal diseases, blast poses a serious threat to the yield and quality of rice globally. It is caused by the pathogen Pyricularia grisea. Therefore, the development of rapid, accurate, and portable microfluidic detection system for Pyricularia grisea is important for the control of rice blast. This study presents an integrated microfluidic detection system for the rapid and sensitive detection of Pyricularia grisea using the LAMP detection method. The microfluidic detection system includes a microfluidic chip, a temperature control module, and an OpenMv camera. The micro-mixing channels with shear structures improve the mixing efficiency to about 98%. Flow-blocking valves are used to reduce reagent loss in the reaction chamber. The temperature control module is used to heat the reaction chamber, maintaining a stable temperature of 65 °C. The microfluidic chip detection chamber is used for image inspection using an OpenMv camera. The developed system can detect Pyricularia grisea in the range of 10 copies/μL–10⁵ copies/μL within 45 min. Specificity and interference experiments were performed on Pyricularia grisea, validating the method’s good reliability. This LAMP detection system based on a microfluidic chip has strong potential in the early and effective detection of rice blast. Full article

Considering that neurological injuries cannot typically self-recover, there is a need to develop new methods to study neuronal outgrowth in a controllable manner in vitro. In this study, a precise flow-controlled microfluidic system featuring custom-designed chambers that integrate laser-microstructured polyethylene terephthalate (PET) substrates comprising microgrooves (MGs) was developed to investigate the combined effect of shear stress and topography on Neuro-2a (N2a) cells’ behavior. The MGs were positioned parallel to the flow direction and the response of N2a cells was evaluated in terms of growth and differentiation. Our results demonstrate that flow-induced shear stress could inhibit the differentiation of N2a cells. This microfluidic system could potentially be used as a new model system to study the impact of shear stress on cell differentiation. Full article

On-chip microfluidics are advanced in vitro models that simulate lung tissue’s native 3D environment more closely than static 2D models to investigate the complex lung architecture and multifactorial processes that lead to pulmonary disease. Current microfluidic systems can be restrictive in the quantities of biological sample that can be retrieved from a single micro-channel, such as RNA, protein, and supernatant. Here, we describe a newly developed large-scale airway-on-chip model that employs a surface area for a cell culture wider than that in currently available systems. This enables the collection of samples comparable in volume to traditional cell culture systems, making the device applicable to any workflow utilizing these static systems (RNA isolation, ELISA, etc.). With our construction method, this larger culture area allows for easier handling, the potential for a wide range of exposures, as well as the collection of low-quantity samples (e.g., volatiles or mitochondrial RNA). The model consists of two large polydimethylsiloxane (PDMS) cell culture chambers under an independent flow of medium or air, separated by a semi-permeable polyethylene (PET) cell culture membrane (23 μm thick, 0.4 μm pore size). Each chamber carries a 5 × 18 mm, 90 mm² (92 mm² with tapered chamber inlets) surface area that can contain up to 1–2 × 10⁴ adherent structural lung cells and can be utilized for close contact co-culture studies of different lung cell types, including airway epithelial cells, fibroblasts, smooth muscle cells, and endothelial cells. The parallel bi-chambered design of the chip allows for epithelial cells to be cultured at the air–liquid interface (ALI) and differentiation into a dense, multi-layered, pseudostratified epithelium under biological flow rates. This millifluidic airway-on-chip advances the field by providing a readily reproducible, easily adjustable, and cost-effective large-scale fluidic 3D airway cell culture platform. Full article

Gas embolism is a rare but life-threatening process characterized by the presence of gas bubbles in the venous or arterial systems. These bubbles, if sufficiently large or numerous, can block the delivery of oxygen to critical organs, in particular the brain, and subsequently they can trigger a cascade of adverse biochemical reactions with severe medical outcomes. Despite its critical nature, gas embolism remains poorly understood, necessitating extensive investigation, particularly regarding its manifestations in the human body and its modulation by various biological conditions. However, given its elusive nature, as well as potential lethality, gas embolism is extremely difficult to study in vivo, and nearly impossible to be the subject of clinical trials. To this end, we developed a microfluidic device designed to study in vitro the impact of blood properties and vascular geometries on the formation and evolution of gas bubbles. The system features a biomimetic vascular channel surrounded by two pressure chambers, which induce the genesis of bubbles under varying circumstances. The bubble parameters were correlated with different input parameters, i.e., channel widths, wall thicknesses, viscosities of the artificial blood, and pressure levels. Smaller channel widths and higher equivalent hematocrit concentrations in synthetic blood solutions increased the nucleation density and bubble generation frequencies. Small channel widths were also more prone to bubble formation, with implications for the vulnerability of vascular walls, leading to increased risks of damage or compromise to the integrity of the blood vessels. Larger channel widths, along with higher equivalent hematocrit concentrations, translated into larger bubble volumes and decreased bubble velocities, leading to an increased risk of bubble immobilization within the blood vessels. This biomimetic approach provides insights into the impact of patient history and biological factors on the incidence and progression of gas embolism. Medical conditions, such as anemia, along with anatomical features related to age and sex—such as smaller blood vessels in women and children or larger vascular widths in adult men—affect the susceptibility to the initiation and progression of gas embolism, explored here in vitro through the development of a controlled, physiological-like environment. The analysis of the videos that recorded gas embolism events in vitro for systems where pressure is applied laterally on the microvasculature with thin walls, i.e., 50 μm or less, suggests that the mechanism of gas transfer for the pressure area to the blood is based on percolation, rather than diffusion. These findings highlight the importance of personalized approaches in the management and prevention of gas embolism. Full article

In this paper, enhanced rotational circulation in a circular microfluidic chamber driven by dual focused surface-acoustic-wave (SAW) beams is presented. To characterize the resonant frequency and focusing effect, we simulate the focused SAW field excited by an arc-shaped interdigital transducer patterned on a 128°Y-cut lithium-niobate (LiNbO₃) substrate using a finite element method. A full three-dimensional perturbation model of the combined system of the microfluidic chamber and the SAW device is conducted to obtain the acoustic pressure and acoustic streaming fields, which show rotational acoustic pressure and encircling streaming resulted in the chamber. Accordingly, the SAW acoustofluidic system is realized using microfabrication techniques and applied to perform acoustophoresis experiments on submicron particles suspending in the microfluidic chamber. The result verifies the rotational circulation motion of the streaming flow, which is attributed to enhanced angular momentum flux injection and Eckart streaming effect through the dual focused SAW beams. Our results should be of importance in driving particle circulation and enhancing mass transfer in chamber embedded microfluidic channels, which may have promising applications in accelerating bioparticle or cell reactions and fusion, enhancing biochemical and electrochemical sensing, and efficient microfluidic mixing. Full article

Hematological analysis is crucial for diagnosing and monitoring blood-related disorders. Nevertheless, conventional hematology analyzers remain confined to laboratory settings due to their high cost, substantial space requirements, and maintenance needs. Herein, we present a portable cell tracking velocimetry (CTV) device for the precise measurement of the magnetic susceptibility of biological entities at the single-cell level, focusing on red blood cells (RBCs) in this work. The system integrates a microfluidic channel positioned between permanent magnets that generate a well-defined magnetic field gradient (191.82 TA/mm²). When the cells are injected into the chamber, their particular response to the magnetic field is recorded and used to estimate their properties and quantify their intracellular hemoglobin (Hb) concentration. We successfully track over 400 RBCs per condition using imaging and trajectory analysis, enabling detailed characterizations of their physical and magnetic properties. A comparison of the mean corpuscular hemoglobin measurements revealed a strong correlation between our CTV system and standard ultraviolet–visible (UV-Vis) spectrophotometry (23.1 ± 5.8 pg vs. 22.4 ± 3.9 pg, p > 0.05), validating the accuracy of our measurements. The system’s single-cell resolution reveals population distributions unobtainable through conventional bulk analysis methods. Thus, this portable CTV technology provides a rapid, label-free approach for magnetic cell characterization, offering new possibilities for point-of-care hematological analysis and field-based research applications. Full article

‘Organ-on-a-chip’ technology is a promising and rapidly evolving model in biological research. This innovative microfluidic cell culture device was created using a microchip with continuously perfused chambers, populated by living cells arranged to replicate physiological processes at the tissue and organ levels. By consolidating multicellular structures, tissue–tissue interfaces, and physicochemical microenvironments, these microchips can replicate key organ functions. They also enable the high-resolution, real-time imaging and analysis of the biochemical, genetic, and metabolic activities of living cells in the functional tissue and organ contexts. This technology can accelerate research into tissue development, organ physiology and disease etiology, therapeutic approaches, and drug testing. It enables the replication of entire organ functions (e.g., liver-on-a-chip, hypothalamus–pituitary-on-a-chip) or the creation of disease models (e.g., amyotrophic lateral sclerosis-on-a-chip, Parkinson’s disease-on-a-chip) using specialized microchips and combining them into an integrated functional system. This technology allows for a significant reduction in the number of animals used in experiments, high reproducibility of results, and the possibility of simultaneous use of multiple cell types in a single model. However, its application requires specialized equipment, advanced expertise, and currently incurs high costs. Additionally, achieving the level of standardization needed for commercialization remains a challenge at this stage of development. Full article