EDTA-treated cotton-thread microfluidic device used for one-step whole blood plasma separation and assay

Advances in textile-based microfluidics for biomolecule sensing

Textile-based microfluidic biosensors represent an innovative fusion of various multidisciplinary fields, including bioelectronics, material sciences, and microfluidics. Their potential in biomedicine is significant as they leverage textiles to achieve high demands of biocompatibility with the human body and conform to the irregular surfaces of the body. In the field of microfluidics, fabric coated with hydrophobic materials serves as channels through which liquids are transferred in precise amounts to the sensing element, which in this case is a biosensor. This paper presents a condensed overview of the current developments in textile-based microfluidics and biosensors in biomedical applications over the past 20 years (2005-2024). A literature search was performed using the Scopus database. The fabrication techniques and materials used are discussed in this paper, as these will be key in various modifications and advancements in textile-based microfluidics. Furthermore, we also address the gaps in the application of textile-based microfluidic analytical devices in biomedicine and discuss the potential solutions. Advances in textile-based microfluidics are enabled by various printing and fabric manufacturing techniques, such as screen printing, embroidery, and weaving. Integration of these devices into everyday clothing holds promise for future vital sign monitoring, such as glucose, albumin, lactate, and ion levels, as well as early detection of hereditary diseases through gene detection. Although most testing currently takes place in a laboratory or controlled environment, this field is rapidly evolving and pushing the boundaries of biomedicine, improving the quality of human life.

Pronounced effect of lamination on plasma separation from whole blood by microfluidic paper-based analytical devices

Many diseases are detected through blood tests. Currently, most blood tests are done on plasma instead of whole blood because of the interference of blood cells on detection results. Here, we developed a laminated microfluidic paper-based analytical device (L-μPAD) for the separation of plasma from whole blood without using plasma separation membrane (PSM). A lateral flow design consisting of a circular sampling zone and rectangular detection zone was patterned on the paper substrate using laser printing technology. The μPAD was then laminated after impregnation with KCl solution. Lamination and electrolyte addition represented synergistic effects on the separation by controlling the pore size of the paper. In addition, by preventing evaporation on one hand and squeezing paper pores on the other hand, lamination caused longer movement of the separated plasma, the longest plasma path reported so far. The separation process was monitored using colorimetric reagent bromocresol green and scanning electron microscopy. The process of separation was completed in less than 90s without significant hemolysis and the separated plasma was far from the interfering effect of red blood cells. We used the device for the determination of serum albumin. However, it represents the potential for point-of-care testing in multi-assay experiments too.

Microfluidic paper and thread-based separations: Chromatography and electrophoresis

Paper and thread are widely used as the substrates for fabricating low-cost, disposable, and portable microfluidic analytical devices used in clinical, environmental, and food safety monitoring. Concerning separation methods including chromatography and electrophoresis, these substrates provide unique platforms for developing portable devices. This review focuses on summarizing recent research on the miniaturization of the separation techniques using paper and thread. Preconcentration, purification, desalination, and separation of various analytes are achievable using electrophoresis and chromatography methods integrated with modified or unmodified paper/thread wicking channels. A variety of 2D and 3D designs of paper/thread platforms for zone electrophoresis, capillary electrophoresis, and modified/unmodified chromatography are discussed with emphasis on their limitation and improvements. The current progress in the signal amplification strategies such as isoelectric focusing, isotachophoresis, ion concentration polarization, isoelectric focusing, and stacking methods in paper-based devices are reviewed. Different strategies for chromatographic separations based on paper/thread will be explained. The separation of target species from complex samples and their determination by integration with other analytical methods like spectroscopy and electrochemistry are well-listed. Furthermore, the innovations for plasma and cell separation from blood as an important human biofluid are presented, and the related paper/thread modification methods are explored.

Last Trends in Point-of-Care (POC) Diagnostics for the Management of Hematological Indices in Home Care Patients

Today, complete blood count (CBC) analyses are highly automated and allow for high throughput and accurate and reliable results. However, new analytical tools are in great demand to provide simple, rapid and cost-effective management of hematological indices in home care patients. Chronic disease monitoring at home has become a benefit for patients who are finding cost savings in programs designed to monitor/treat patients in offsite locations. This review reports the latest trends in point-of-care (POC) diagnostics useful for home testing of key hematological counts that may be affected during home therapy treatment.

Engineering a sustainable future for point-of-care diagnostics and single-use microfluidic devices

Single-use, disposable, point-of-care diagnostic devices carry great promise for global health, including meeting urgent needs for testing and diagnosis in places with limited laboratory facilities. Unfortunately, the production and disposal of single-use devices, whether in lateral flow assay, cartridges, cassettes, or lab-on-chip microfluidic format, also poses significant challenges for environmental and human health. Point-of-care devices are commonly manufactured from unsustainable polymeric materials derived from fossil sources. Their disposal often necessitates incineration to reduce infection risk, thereby creating additional release of CO2. Many devices also contain toxic chemicals, such as cyanide derivatives, that are damaging to environmental and human health if not disposed of safely. Yet, in the absence of government regulatory frameworks, safe and sustainable waste management for these novel medical devices is often left unaddressed. There is an urgent need to find novel solutions to avert environmental and human harm from these devices, especially in low- and middle-income countries where waste management infrastructure is often weak and where the use of point-of-care tests is projected to rise in coming years. We review here common materials used in the manufacture of single-use point-of-care diagnostic tests, examine the risks they pose to environmental and human health, and investigate replacement materials that can potentially reduce the impact of microfluidic devices on the production of harmful waste. We propose solutions available to point-of-care test developers to start embedding sustainability at an early stage in their design, and to reduce their non-renewable plastic consumption in research and product development.

Thread-based isotachophoresis coupled with desorption electrospray ionization mass spectrometry for clean-up, preconcentration, and determination of alkaloids in biological fluids

A thread-based isotachophoresis method coupled with desorption electrospray ionization mass spectrometry (TB-ITP-DESI-MS) was developed and applied for clean-up, preconcentration, and determination of alkaloids in biological fluids. This simple approach enables the focusing and rapid analysis of analytes of interest in complex matrices that are otherwise challenging using direct ambient mass spectrometry. The TB-ITP platform components were rapidly and reproducibly fabricated at low-cost using 3D printing. A single string of nylon 6 thread was used as the electrophoresis substrate and a cotton knot, tied to the nylon thread, was used as the trapping zone of the ITP focused model analytes (coptisine, berberine and palmatine). The trapping efficiency was evaluated upon different commercially available threads with different chemical properties and cotton was selected as the best material due to its highest trapping efficiency and subsequent DESI-MS ionization efficiency. Up to 11.6-fold increase in signal to noise ratio (S/N) was obtained using the proposed method compared to direct DESI-MS detection, due to the reduced matrix interference and focusing. The results demonstrated that the TB-ITP-DESI-MS approach is a viable solution for the analysis of complicated biological fluid samples.

Microfluidic tools for veterinary and zoonotic disease diagnostics

Animal disease diagnostics has linked as the cause and cure of any disease. It also plays a vital role in disease management and prevention. A small outbreak of disease can pose a threat to the entire animal community as we realized in corona pandemic. Thus, to ensure the overall welfare of animals and disease spread monitoring, the development of detection tools for veterinary diagnosis becomes essential. Currently, the animal disease diagnosis is relied on laboratory-based testing. There is a parallel necessity for rapid, reliable and low-cost diagnostic tests to be done by intervention of growing area such as microfluidic platform. Therefore, in this chapter, we have discussed about various microfluidic platform and their application for early diagnosis of veterinary disease. Followed by, we also lightened on future perspective of role of microfluidic in animal disease diagnostics.

A pump-free microfluidic device for fast magnetic labeling of ischemic stroke biomarkers

This research proposes a low-cost and simple operation microfluidic chip to enhance the magnetic labeling efficiency of two ischemic stroke biomarkers: cellular fibronectin (c-Fn) and matrix metallopeptidase 9 (MMP9). This fully portable and pump-free microfluidic chip is operated based on capillary attractions without any external power source and battery. It uses an integrated cellulose sponge to absorb the samples. At the same time, a magnetic field is aligned to hold the target labeled by the magnetic nanoparticles (MNPs) in the pre-concentrated chamber. By using this approach, the specific targets are labeled from the beginning of the sampling process without preliminary sample purification. The proposed study enhanced the labeling efficiency from 1 h to 15 min. The dynamic interactions occur in the serpentine channel, while the crescent formation of MNPs in the pre-concentrated chamber, acting as a magnetic filter, improves the biomarker-MNP interaction. The labeling optimization by the proposed device influences the dynamic range by optimizing the MNP ratio to fit the linear range across the clinical cutoff value. The limits of detection (LODs) of 2.8 ng/mL and 54.6 ng/mL of c-Fn measurement were achieved for undiluted and four times dilutions of MNP, respectively. While for MMP9, the LODs were 11.5 ng/mL for undiluted functionalized MNP and 132 ng/mL for four times dilutions of functionalized MNP. The results highlight the potential use of this device for clinical sample preparation and specific magnetic target labeling. When combined with a detection system, it could also be used as an integrated component of a point-of-care platform.

Understanding microbeads stacking in deformable Nano-Sieve for Efficient plasma separation and blood cell retrieval

Efficient separation of blood cells and plasma is key for numerous molecular diagnosis and therapeutics applications. Despite various microfluidics-based separation strategies having been developed, there is still a need for a simple, reliable, and multiplexing separation device that can process a large volume of blood. Here we show a microbead-packed deformable microfluidic system that can efficiently separate highly purified plasma from whole blood, as well as retrieve blocked blood cells from the device. To support and rationalize the experimental validation of the proposed device, a highly accurate model is constructed to help understand the link between the mechanical properties of the microfluidics, flow rate, and microbeads packing/leaking based on the microscope imaging and the optical coherence tomography (OCT) scanning. This deformable nano-sieve device is expected to offer a new solution for centrifuge-free diagnosis and treatment of bloodborne diseases and contribute to the design of next-generation deformable microfluidics for separation applications.

Microfluidic devices based on textile threads for analytical applications: state of the art and prospects

Microfluidic devices based on textile threads have interesting advantages when compared to systems made with traditional materials, such as polymers and inorganic substrates (especially silicon and glass). One of these significant advantages is the device fabrication process, made more cheap and simple, with little or no microfabrication apparatus. This review describes the fundamentals, applications, challenges, and prospects of microfluidic devices fabricated with textile threads. A wide range of applications is discussed, integrated with several analysis methods, such as electrochemical, colorimetric, electrophoretic, chromatographic, and fluorescence. Additionally, the integration of these devices with different substrates (e.g., 3D printed components or fabrics), other devices (e.g., smartphones), and microelectronics is described. These combinations have allowed the construction of fully portable devices and consequently the development of point-of-care and wearable analytical systems.

Low-Cost Optical Assays for Point-of-Care Diagnosis in Resource-Limited Settings

Readily deployable, low-cost point-of-care medical devices such as lateral flow assays (LFAs), microfluidic paper-based analytical devices (μPADs), and microfluidic thread-based analytical devices (μTADs) are urgently needed in resource-poor settings. Governed by the ASSURED criteria (affordable, sensitive, specific, user-friendly, rapid and robust, equipment-free, and deliverability) set by the World Health Organization, these reliable platforms can screen a myriad of chemical and biological analytes including viruses, bacteria, proteins, electrolytes, and narcotics. The Ebola epidemic in 2014 and the ongoing pandemic of SARS-CoV-2 have exemplified the ever-increasing importance of timely diagnostics to limit the spread of diseases. This review provides a comprehensive survey of LFAs, μPADs, and μTADs that can be deployed in resource-limited settings. The subsequent commercialization of these technologies will benefit the public health, especially in areas where access to healthcare is limited.

Recent advances in thread-based microfluidics for diagnostic applications

Over the past decades, researchers have been seeking attractive substrate materials to keep microfluidics improving to outbalance the drawbacks and issues. Cellulose substrates, including thread, paper and hydrogels are alternatives due to their distinct structural and mechanical properties for a number of applications. Thread have gained considerable attention and become promising powerful tool due to its advantages over paper-based systems thus finds numerous applications in the development of diagnostic systems, smart bandages and tissue engineering. To the best of our knowledge, no comprehensive review articles on the topic of thread-based microfluidics have been published and it is of significance for many scientific communities working on Microfluidics, Biosensors and Lab-on-Chip. This review gives an overview of the advances of thread-based microfluidic diagnostic devices in a variety of applications. It begins with an overall introduction of the fabrication followed by an in-depth review on the detection techniques in such devices and various applications with respect to effort and performance to date. A few perspective directions of thread-based microfluidics in its development are also discussed. Thread-based microfluidics are still at an early development stage and further improvements in terms of fabrication, analytical strategies, and function to become low-cost, low-volume and easy-to-use point-of-care (POC) diagnostic devices that can be adapted or commercialized for real world applications.

Life-Saving Threads: Advances in Textile-Based Analytical Devices

Novel approaches that incorporate electrofluidic and microfluidic technologies are reviewed to illustrate the translation of traditional enclosed structures into open and accessible textile based platforms. Through the utilization of on-fiber and on-textile microfluidics, it is possible to invert the typical enclosed capillary column or microfluidic "chip" platform, to achieve surface accessible efficient separations and fluid handling, while maintaining a microfluidic environment. The open fiber/textile based fluidics approach immediately provides new possibilities to interrogate, manipulate, redirect, extract, characterize, and quantify solutes and target species at any point in time during such processes as on-fiber electrodriven separations. This approach is revolutionary in its simplicity and provides many potential advantages not otherwise afforded by the more traditional enclosed platforms.

Blood Plasma Separation Using a Fidget-Spinner

In this study, we present a simple, hand-powered, and electricity-free centrifuge platform based on a commercially available "fidget-spinner." The centrifugal force provided by this inexpensive and easy-to-use toy is sufficient to separate whole blood, producing a plasma yield rate and purity of 30% and 99%, respectively, separated in as little as 4-7 min. We verified the separated plasma by performing a paper-based HIV-1 p24 capsid protein enzyme-linked immunosorbent assay, which achieved a recovery rate of up to 98%, indicating the plasma features extremely low matrix interference effects. These results demonstrate the reliability of the platform for practical use, in addition to greatly reducing the overall cost and time of analysis while retaining detection precision, making it suitable for medical applications in resource-limited regions of the world.

Microfluidic thread based electroanalytical system for green chromatographic separations

The use of miniaturized chromatographic systems is an important strategy for reducing the consumption of supplies related to separations, allowing the development of more sustainable analytical methodologies. However, the high cost and complexity in the production of these systems combined with the operational difficulties and the need for the use of solvent and sample pretreatment are challenges to be overcome in order to make the chromatographic methods greener. Here, we report the construction and development of a low cost microfluidic system for green and solvent-free chromatographic separations with electrochemical detection integrated into cotton threads without the use of any mechanical pumping to transport the solutions. The manufacture of the proposed system was performed by simple assembly of the components, with the separation of the species based on an ion exchange mechanism and detection using gold electrodes manufactured directly on the cotton threads. A linear range of 0.025-5.0 mM was obtained for the effective separation of ascorbic acid (AA) and dopamine (DA) with detection limits of 2.89 μM (for AA) and 4.41 μM (for DA). Each analysis was performed at a low cost (less than 0.01 dollars), and with a small volume of waste generated (107.1 μL). So, the proposed system was successfully employed to determine the levels of AA and DA present in the tears of healthy volunteers without sample pretreatment, indicating the good analytical performance of the system and the possibility of performing greener chromatographic separations.

Microfluidic blood plasma separation for medical diagnostics: is it worth it?

Circulating biomarkers are on the verge of becoming powerful diagnostic tools for various human diseases. However, the complex sample composition makes it difficult to detect biomarkers directly from blood at the bench or at the point-of-care. Blood cells are often a source of variability of the biomarker signal. While the interference of hemoglobin is a long known source of variability, the release of nucleic acids and other cellular components from hemocytes is a new concern for measurement and detection of circulating extracellular markers. Research into miniaturised blood plasma separation has been thriving in the last 10 years (2006-2016). Most point-of-care systems need microscale blood plasma separation, but developed solutions differ in complexity and sample volume range. But could blood plasma separation be avoided completely? This focused review weights the advantages and limits of miniaturised blood plasma separation and highlights the most interesting advances in direct capture as well as smart blood plasma separation.