Understanding electroosmotic flow of non-Newtonian fluids in micro- and nanochannels is crucial for the electrokinetic handling of chemical and biological samples that often exhibit viscoelastic, shear-thinning, or shear-thickening behavior. A theoretical model is developed for the generalized electroosmotic core–annular flow of power-law fluids in cylindrical microchannels. Both approximate and simplified analytical solutions are derived under their respective appropriate assumptions and validated by benchmarking against the exact solution. The simplified analytical solutions under the thin electric double layer assumption are further used to characterize the parametric effects of the annular-fluid thickness and flow behavior index on the electroosmotic velocity and flow rate. The presented analytical solutions are useful for predicting the wall-induced polymer depletion or adsorption effect on the electroosmotic velocity of power-law fluids. They will also benefit the study of electroosmotic pumping and electrokinetic energy conversion in non-Newtonian fluids.
Droplet microfluidics has become a modern technology for chemical, biological, electrochemical and energy applications, which helps in the manipulation of a discrete droplet in a size range from 10 pL to 100 nL. Compared to conventional techniques, the droplet-based platform provides a 10–100-fold faster mass-transfer rate, reduces reagent usage by up to 95%, decreases reaction time from hours to minutes, and enables ultra-efficient screening of 103–104 droplets s-1. The capabilities have greatly advanced the discovery and optimization of advanced materials, catalysts, and bioelectrochemical systems. This review covers all aspects of droplet generation, manipulation, detection methods and the latest progress in device manufacturing for energy and bioelectrochemical applications. Representative studies show that the droplet-assisted microfluidic platforms can be used to screen electrocatalysts within minutes, can be used for membrane-less electrochemical systems with current densities over 100–500 mA cm-2, and can be used to reduce material consumption by over 80% with enhanced catalyst utilization. Droplet microfluidics has enabled rapid microbial screening, improved control of biofilms, removal of up to 95% chemical oxygen demand (COD), and microbial electrolysis system with hydrogen production rates up to 314 ± 17 m3 H2 m-3 reactor per day with optimized electrode configuration in bioelectrochemical applications. The review also emphasizes the use of AI, machine learning, digital microfluidics and automation for autonomous experimentation and optimization based on data. Finally, the current challenges regarding scalability and standardization of devices, long-term operational stability and commercialization of devices are critically discussed. Overall, droplet microfluidics is a versatile and scalable platform that has the potential to speed up the next-generation of sustainable energy technologies and to bioelectrochemical systems by providing more precise control of reactions, high throughput experimentation, and more efficient use of resources.
Viral encephalitis causes substantial neurological morbidity and mortality through the combined effects of direct viral injury, blood–brain barrier (BBB) dysfunction, and dysregulated communication among neural, vascular, and immune cells. Extracellular vesicles (EVs) are increasingly recognized as mediators of this communication because they transfer proteins, lipids, viral constituents, cytokine-related signals, and regulatory RNAs between neurons, astrocytes, microglia, endothelial cells, and peripheral immune cells. Depending on their cellular origin and cargo, EVs may support antiviral defense or propagate viral dissemination, neuroinflammation, barrier injury, and persistent neurological sequelae. This narrative review synthesizes evidence for an EV–neuroimmune axis in viral encephalitis and evaluates how that evidence could inform the design of brain organoid-on-a-chip (BOoC) models. The review distinguishes established findings from a proposed integrated platform that would combine patient-derived brain organoids, a BBB-interposed vascular and immune compartment, real-time EV tracking, transendothelial electrical resistance and electrophysiological sensing, and multi-omics analysis. Existing studies support several individual components of this framework, but a fully integrated EV–BOoC system with closed-loop artificial intelligence (AI) control has not yet been demonstrated for viral encephalitis. Accordingly, digital twins, autonomous treatment optimization, and patient-specific clinical prediction are presented as future research directions rather than current capabilities. This calibrated framework identifies measurable design requirements, evidence gaps, and translational priorities for mechanistic studies, biomarker discovery, and precision therapeutic screening.
IntroductionWe present a lab-on-foil (LOF) microfluidic platform for point-of-care (POC) genetic testing, combining roll-to-roll UV nanoimprint lithography (R2R UV-NIL) with on-chip loop-mediated isothermal amplification (LAMP) and sequence-specific detection of single nucleotide polymorphisms (SNPs).MethodsThe integrated system comprises an R2R UV-NIL-fabricated microfluidic chip with a portable reader enabling controlled isothermal incubation, automated reagent handling, and chemiluminescence-based signal detection. Analytical validation was performed using 67 genomic DNA samples with known LCT –13910C>T genotypes, with 167 measurement runs conducted across four reader instruments. Genotype classification was based on allele-specific signal ratios and predefined quality-control criteria.ResultsOf these 167 runs, 49 (29.3%) met the acceptance criteria and were included in the diagnostic performance analysis. Using the final decision thresholds, the assay achieved 100.0% sensitivity and 80.6% specificity for identification of the clinically relevant C/C genotype, with a positive predictive value of 65.0% and a negative predictive value of 100%. Genotype discrimination was achieved within approximately 50 min.DiscussionThe results confirm the compatibility of scalable R2R-fabricated microfluidic chips with integrated nucleic acid amplification and allele-specific detection workflows. While the analytical assay principle proved functional, overall system performance was primarily limited by fluidic handling, temperature uniformity, and reagent delivery during prototype integration. Overall, the presented platform demonstrates the potential of scalable lab-on-foil technologies for decentralized genetic diagnostics and future multiplexed POC testing applications.
The transient electrophoresis of a weakly charged oil drop of viscosity ηd in an electrolyte solution of viscosity η is investigated theoretically on the basis of the Baygents–Saville model. An analytical expression for the electrophoretic mobility in the Laplace domain is derived, from which an inverse Laplace transform representation for the transient electrophoretic mobility is obtained. It is shown that the resulting expression possesses essentially the same mathematical structure as the dynamic electrophoretic mobility formula recently derived by the author for an oil drop in an oscillating electric field. In fact, the transient mobility expression can be obtained directly from the dynamic mobility expression through an appropriate transformation of parameters, thereby establishing a direct correspondence between the time-domain and frequency-domain descriptions of oil-drop electrophoresis. The actual time-dependent mobility is evaluated numerically by means of numerical inverse Laplace transformation. The effects of the double-layer thickness and drop viscosity on the transient electrophoretic response are examined in detail. Comparisons are also made with the transient electrophoresis of a solid particle and a perfectly conducting drop (mercury drop). The results show that the relaxation time strongly depends on the electrokinetic parameter κa, where a and κ are, respectively, the drop radius and the Debye-Hückel parameter, and decreases in the order κa = 0.1, 1, 10, and ∞. Furthermore, the relaxation time decreases with increasing viscosity ratio ηd/η. The present analysis provides a unified framework connecting transient and dynamic electrophoresis of liquid drops and offers new insight into the relaxation processes governing electrokinetic phenomena.
Continuous health monitoring has the potential to transform disease management by moving biomarker measurements from episodic testing to real-time tracking. Aptamers are promising affinity reagents for this purpose because they can recognize a wide range of targets and can be chemically synthesized, engineered, and integrated with miniaturized sensing platforms. In this Perspective, we discuss the key challenges and opportunities for aptamer-enabled continuous health monitoring. We highlighted the need for sensor-ready aptamers that are validated in relevant biofluids, operate within clinically relevant concentration ranges, and maintain specificity in complex matrices. We also discuss challenges in signal transduction, surface immobilization, binding kinetics, regeneration, long-term stability, biofouling, nonspecific binding, and translation. We argue that future progress will require moving beyond aptamers that simply bind targets toward aptamers that function reliably in real sensor formats. Addressing these challenges will help aptamer-based sensors move from proof-of-concept demonstrations toward practical tools for continuous, real-time health monitoring.
IntroductionCurrent molecular diagnostic (MDx) platforms rely on silica-coated surfaces for nucleic acid extraction. This requires multiple wash buffers and complex automation, thereby creating cost and usability barriers for resource-limited settings. Several modifications of MDx towards affordability adopt miniaturization technologies such as microfluidics, underscoring the potential impact of material reduction on MDx cost. Most advancements, however, replicate the same silica-based process steps leaving its cost-implication unaddressed. This study positions oligonucleotide-functionalized surfaces as a potential alternative approach for DNA capture with the potential for future integration into lab-on-a-chip (LoC) technologies.MethodsHybridization-based genomic DNA and oligo capture were first validated using oligonucleotide-functionalized microparticles as a surrogate for polycarbonate plastic surfaces. Polycarbonate plastic was selected due to its biocompatibility, thermal tolerance, and the possibility of primer immobilization through amide bond. To enable the immobilization of a high concentration of oligonucleotides on polycarbonate plastics, their tubes were sequentially treated through acetone splash (10 s exposure) and UV photo-oxidation (10 min) to increase their carboxyl density.ResultsCombined acetone and UV treatments increased the tubes’ carboxyl density 2- fold (2.02 × 10–3 to 4.0 × 10–3nmol/mm2). To further improve the primer-carrying capacity of the tube surface, the oligonucleotide loading capacity of two linker molecules, branched polyethyleneimine (BPEI) and ethylenediamine (EA), was compared. BPEI linkers provided 2.6-fold higher oligonucleotide payload compared to ethylenediamine. The concentration of surface-immobilized oligonucleotides available for DNA capture was quantified fluorometrically from RFU values referenced against a calibration curve. An average of 0.125 ± 0.018 μM and 0.0296 ± 0.0132 μM oligonucleotides were immobilized in a 25μL working volume using BPEI and EA respectively.DiscussionAlthough the concentration achieved using BPEI is theoretically compatible with 2-primer amplification chemistries such as PCR and recombinase polymerase amplification (RPA), further optimization is required to enable LAMP. Optimization efforts addressing the tubes’ tapered geometry and the need for mixing during functionalization is recommended to achieve higher primer concentrations. This proof-of-concept establishes preliminary technical feasibility of primer-functionalized surfaces as a potential alternative to silica-based nucleic acid extraction, pending full workflow integration. The validated surface engineering approach provides a development pathway for a cost-effective diagnostic platforms suitable for resource-limited settings.
Paper-based microfluidics has emerged as a promising platform for low-cost analytical and biological assays. However, fabrication of hydrophobic barriers on porous substrates remains largely dependent on direct wax printing, which limits patterning flexibility, requires specialized equipment, and constrains scalability. Here, we present a simple and versatile wax transfer technique that enables reliable replication of wax micropatterns from one porous substrate to another. The method leverages controlled wettability, thermal activation, and applied pressure to achieve efficient and reproducible pattern transfer. The resulting patterned substrates display well-defined hydrophobic–hydrophilic regions suitable for microfluidic applications. We demonstrate the versatility of the approach through applications in cell culture and biochemical assays, including the growth and spatial confinement of cervical and breast cancer cells, as well as Folin–Lowry protein quantification in saliva samples. Notably, wax-transferred patterns provide spatial confinement of assay signals, while maintaining biocompatibility, suitability for biological applications, and structural integrity of the substrate. The simplicity of the process, compatibility with diverse porous materials, and long-term stability of donor patterns highlight its potential for scalable and distributed fabrication. Overall, this work establishes a porous-to-porous transfer strategy that expands the design space of paper-based microfluidics and provides a practical pathway toward accessible, manufacturable, and widely deployable lab-on-paper technologies.
In the last 20 years, micro- and nano-textured surfaces have been produced by means of various surface engineering processes, imparting enhanced properties, such as tunable wettability from superhydrophilicity to superhydrophobicity, tunable optical, and antifouling or antibacterial properties, to the substrates on which micro-nanotexturing has been imposed. While these properties have been readily explored in open substrate surfaces presented in numerous publications, their implementation in microfluidic and lab-on-a-chip devices is less frequent although increasingly important through the incorporation of such surfaces as microfluidic walls. In this review article, we will focus on microfluidic and lab-on-a-chip devices in which micro-nanotextured surfaces have been integrated as passive valves and means of liquid transport, sensitive sensors, enhanced bacteria capturing and lysing devices, only to mention a few of their enhanced functionalities. The added-value of the incorporated surfaces in the device performance will be presented and analyzed. The aim is to provide a systematic elucidation into the multifaceted advantages and enhanced functional capabilities of micro-nanotextured surfaces when integrated within microfluidic systems.
Single-use biosensors such as lateral flow assays (LFAs) have transformed point-of-care (PoC) diagnostics, yet their environmental footprint is rarely considered during design. As deployment scales globally, this oversight raises pressing sustainability concerns. Although early integration of eco-design principles could reduce environmental burdens, biosensor developers lack practical tools to operationalize sustainability during early-stage development. This practical review proposes a quantitative, multi-scale design methodology that bridges materials selection and system-level performance. We compile environmental indicators for materials commonly used in biosensors and conduct a PRISMA-based review of life-cycle assessments, revealing distinct orders of magnitude in carbon footprint across LFAs, instrumented devices, and PCR-based systems. Building on these findings, we introduce the Environmental Cost of Performance (ECoP), a simplified eco-design metric that links analytical sensitivity to environmental impact and reframes conventional performance-driven technology roadmaps into performance-impact trade-off approaches. This practical review is intended to serve as a quantitative toolbox, enabling scientists to integrate eco-design principles into their development practices and to arbitrate between design options using operational environmental metrics. In doing so, it represents a first step beyond generic sustainability claims, paving the way for broader impact assessments that integrate environmental, economic, and societal dimensions into PoC diagnostic innovation.
Microfluidic technologies underpin many advances in diagnostics and life-science tools, yet only a minority of laboratory concepts survive the transition to manufacturable products. Drawing on development experience across multiple industry-facing projects within the Microfluidics Innovation Hub, we identify the recurring reasons for this gap: weak market definition, over-integrated device architectures, early design choices misaligned with scalable materials and processes, and manufacturing workflows that become unnecessarily complex. These issues are often amplified when teams approach product development with a laboratory mindset rather than a product mindset. This Perspective distils a practical framework—spanning user alignment, design discipline, manufacturability, and supply-chain strategy—to help researchers and founders anticipate translational pitfalls and develop microfluidic systems capable of succeeding beyond the lab. We argue that successful translation requires early convergence of market definition, constrained system design, and manufacturable architectures, supported by development strategies that treat manufacturing and regulatory realities as primary design inputs rather than downstream optimisation challenges.
Most analytical applications are run with conventional high-performance liquid chromatography (LC) technology, however the separation of highly complex mixtures is still challenging. One key challenge is to minimize band broadening caused by the velocity profile within the channel. Miniaturization of flow-through channels (between particles) has been mainly used to overcome this challenge, yet physical constraints limit further advancements. Moreover, packed columns often result in long separation times, restricting practical improvements in column design. Vortex Liquid Chromatography (Vortex LC) introduces a concept in which lateral vortex flows are generated to enhance transverse mass transfer and reduce axial dispersion. As a result, larger characteristic flow dimensions can be used while still achieving the separation performance normally associated with smaller channels. When identical dimensions are used in vortex LC mode, a higher, unprecedented performance can be achieved. Generating stable vortices requires an additional driving mechanism. We focus on methods that can be scaled to chromatographically relevant, i.e., micron-scale, dimensions.
Biosensors harness biological components to detect and report on specific analytes, offering crucial insights across medicine, environmental monitoring, agriculture, and food security. The convergence of synthetic biology and laboratory-on-a-chip (LoC) technologies is enabling a new generation of biosensors that are programmable, modular, and field-deployable. Synthetic biology provides engineered sensing elements, including bespoke proteins, aptamers, and genetic circuits, that expand the range of detectable analytes while offering tunable sensitivity, specificity, and dynamic range. LoC platforms, in turn, miniaturize fluid handling and analytical processes into integrated microfluidic devices, creating controlled environments that enhance biosensor performance, portability, and biocontainment. Together, these approaches address long-standing barriers in biosensing by coupling biological programmability with physical precision. This review surveys the applications of synthetic biology-LoC integration, from healthcare and environmental monitoring to emerging frontiers, including biocomputing and deep sea exploration. With rapidly accelerating innovation, the potential of these devices can be realized, reshaping the way we diagnose disease, safeguard ecosystems, manage food supplies, and explore new frontiers.
Lab-on-a-chip (LoC) devices have proved their potential for biomedical and analytical applications. Despite their growing demand, their environmental impacts remain insufficiently taken into account. These microfluidic devices are mainly made from petroleum-based materials like PDMS and thermoplastics, whose life-cycle (from resource extraction to disposal) poses ecological and health concerns. In response, a growing number of research papers are exploring bio-based alternatives, such as cellulose, PLA, chitosan, or zein. This review details properties of microfluidic devices made from these bio-based materials compared with more conventional materials, and particularly their impact on the environment from raw material sourcing through manufacturing to disposal. Although many of these materials are still in early stages of research, and published data is limited, developments are promising, and the associated technological challenges must be met. The alternative to plastics used for the manufacture of LoC could be a panel of complementary bio-based materials, locally sourced to support the local economy and limit transport, and which do not lead to new imbalances. This review advocates for a sustainable approach to material selection, encouraging the development of greener microfluidic devices.
Advances in stem cell biology and microengineering have led to the emergence of liver organoids-on-a-chip systems, hybrid platforms that integrate self-organizing three-dimensional organoids with microfluidic devices. These technologies enable more physiologically relevant modeling of human liver biology by enhancing organoid maturation, incorporating dynamic cues such as flow and shear stress, and facilitating multicellular interactions across parenchymal and non-parenchymal compartments. As a result, they provide powerful opportunities to investigate liver development, interrogate mechanisms of disease progression, and assess pharmacological responses with higher fidelity than conventional models. Applications span from studying steatohepatitis and fibrosis to evaluating drug-induced liver injury and patient-specific variability in metabolism. In this Review, we highlight recent progress in liver organoids-on-a-chip systems, discuss their potential in personalized medicine and predictive toxicology, and outline current technical challenges and translational opportunities that will shape their future impact on therapeutic discovery and precision health.
IntroductionThe widespread use of Lateral Flow Assays (LFAs) has significantly improved diagnostic accessibility in low- and middle-income regions, yet their reliance on single-use plastic cassettes poses urgent environmental concerns as conventional plastics persist for centuries, degrading only into harmful microplastics.MethodsThis study evaluated the biodegradability of certified plant-based diagnostic cassettes developed by Okos Diagnostics under field conditions in Nigeria using a 4-month controlled burial study across three soil types: sandy, clayey, and loamy. The biodegradable cassettes, made from certified plant-based polymers, were monitored using precision weight analysis and qualitative degradation assessments, compared against conventional plastic controls.ResultsResults demonstrated statistically significant degradation in biodegradable cassettes with weight increases of 7.44% ± 0.12% (sandy), 7.02% ± 0.08% (clayey), and 11.36% ± 0.16% (loamy soil), which showed the highest degradation rate. Observed initial weight increases primarily reflect moisture uptake and microbial biofilm formation on cassette surfaces rather than net polymer mass gain; these early-stage changes precede fragmentation and mineralization during biodegradation. ANOVA analysis revealed significant differences between soil types (F=15.7, p < 0.001) and materials (F=89.3, p < 0.0001), while plastic controls showed negligible change (1.36% ± 0.04%). Posthoc Tukey analysis showed that degradation in loamy soil was significantly higher than in sandy and clayey soils (p < 0.05).DiscussionThe study validates biodegradable cassettes as eco-friendly alternatives capable of reducing diagnostic waste in resource-limited settings and provides baseline biodegradation data for tropical environments to inform global standards on sustainable diagnostic materials.
The scale up of diagnostic service in many Low-Income Countries (LIC) has greatly improved health outcomes of the populations being served by 21st century laboratory platforms like those seen in High Income Countries (HIC). A challenge because of this scale up is the contribution of increased volume of plastic and hazardous chemical waste that needs to be properly managed with limited options as compared to what is available in HIC. Guanidinium thiocyanate (GTC), as an example, a widely used component of extraction reagents used in Polymerase Chain Reaction (PCR) testing, when inappropriately disposed of can cause harm to animals and the environment because it contains a toxic cyanide compound. While environmental short term disposal methods exist that would improve the practices and offer alternative waste treatment options, challenges in availability of required infrastructure and sustainability remain, thereby limiting their impact. While testing generates revenue, waste associated with testing is a cost that is not adequately funded hence unsustainable in the current environment. The availability of alternative compounds that are less toxic yet can achieve the required actions may provide a lasting solution. Developing platforms geared towards microchemistry as well as the recyclability of the materials used for testing would steer waste/material management in a new direction. We call on diagnostic manufacturers to consider these options upstream of the product lifecycle in the long term that are in line with their internal corporate commitment to sustainability beyond the manufacturing process.
Animal models have long supported biomedical research, particularly in the development of drugs and preclinical testing. Yet, persistent discrepancies between animal data and human clinical outcomes have prompted a critical reassessment of their translational value. Challenges, including biological variability, inadequate methodological reporting, and limited regulatory oversight, particularly in low- and middle-income countries, undermine the reliability of animal research in guiding clinical practice. Organ-on-a-chip (OoC) technology offers a compelling alternative, especially relevant for resource-limited contexts. These microengineered systems enable more accurate modeling of human physiology and better predictions of drug safety and effectiveness, yielding direct benefits for underserved populations. By incorporating patient-derived cells, OoC platforms allow the study of region-specific diseases while fostering international research collaboration. Moreover, such approaches reduce reliance on costly animal research infrastructure, addressing critical barriers in countries like Guatemala, where the legal framework and funding remain limited. We argue that broader adoption of OoC technology is essential to improving research equity, quality, and accessibility worldwide. This perspective reflects the realities and aspirations of the Guatemalan scientific community, where advancing alternatives to animal models is not only a scientific priority but also a pathway to greater participation in global biomedical research.
IntroductionWearable sweat sensors are emerging as non-invasive tools for health monitoring and point-of-care diagnostics. However, their single-use nature and complex manufacturing processes pose significant sustainability challenges. This research integrates Life Cycle Assessment (LCA) at the design stage to address these environmental concerns, using it as a decision-making tool to guide material selection.MethodsWe developed an integrated capacitive sensor for continuous sweat rate and dehydration monitoring. The study’s focus was on replacing conventional silver-printed electrodes with more sustainable alternatives. We specifically investigated the viability of using copper-based laminates and screen-printed graphite as alternative electrode materials, assessing their performance against the original silver electrodes. A comprehensive LCA was performed to evaluate the environmental footprint of the device’s manufacturing and assembly processes.ResultsOur findings demonstrate that both copper-based laminates and screen-printed graphite are viable substitutes for silver-printed electrodes, maintaining functional performance while significantly reducing the device’s environmental impact. The LCA data confirmed that these material substitutions lowered the overall environmental footprint of the wearable sweat sensors.DiscussionThis work underscores the critical role of integrating sustainability principles and tools like LCA early in the design phase of medical devices. By making informed material choices, it is possible to develop functional, high-performance wearable sensors that are also environmentally conscious. This approach offers a practical pathway toward scalable, sustainable, and net-zero healthcare technologies.
Patient-derived cancer cells (PDCCs) have emerged as a key strategy for advancing personalized cancer treatment. Unlike traditional cancer cell lines, PDCCs retain the genetic and phenotypic characteristics of the patient’s original tumor and can more accurately reflect tumor biology. This review explores recent advances in methods for culturing PDCCs, highlighting the role of these models in drug discovery and high-throughput screening of personalized therapeutic options. By establishing living models directly from patient tumors, PDCCs can more faithfully recapitulate tumor heterogeneity and microenvironmental features than traditional cell lines. These cultures bridge laboratory research and clinical reality, allowing functional testing of patients' cancer cells. Despite the promise of PDCCs, their culture remains fraught with challenges, including the extremely low number of cancer cells that can be obtained, difficulty maintaining tumor heterogeneity, low culture initiation success rates, and ethical considerations for using patient tissues. In addition, controversy remains regarding the reproducibility of results between different laboratories and patient samples. By examining the field’s current state, this review identifies gaps in the application of PDCCs, such as limited modeling capabilities for specific tumor types and the lack of comprehensive, scalable protocols for broad clinical use. This article discusses future directions, including integration with advanced microengineering and AI-driven analysis, which have the potential to overcome existing limitations and optimize PDCCs-based therapeutic strategies. PDCCs are expected to transform the future of cancer treatment as they ultimately provide more accurate drug testing and personalized medicine models.
