Microfluidic Paper-based Devices Research Articles

Saturation Equation: An Analytical Expression for Partial Saturation during Wicking Flow in Paper Microfluidic Channels.

The design and fabrication of paper-based microfluidic devices is critically dependent on modeling fluid flow through porous paper membranes. A commonly observed phenomenon is partial saturation, i.e., regions of the paper membrane not being filled completely due to pores of different sizes. The most comprehensive model to date of partial saturation during wicking flow in paper is the Richards equation. However, the solution to the Richards equation requires numerical solvers like COMSOL, which makes it largely inaccessible to the paper microfluidics and lateral flow assay community. There is therefore a need for a simple and appropriate model of partial saturation in paper membranes, easily usable by the wider research community. In the current work, we present an approach to model paper membranes as a bundle of parallel capillaries whose radii follow a two-parameter log-normal distribution. Application of the Washburn equation to the bundle provides a distribution of fluid fronts, which can be used to calculate saturation. Using this approach, we developed the "saturation equation"─an explicit analytical expression to calculate saturation as a function of space and time in 1D wicking flow. Experimentally obtained data for spatiotemporal saturation for four different paper materials were fit to this analytical model to obtain parameters for each material. Results obtained from this analytical model match well with both experimental data and numerical results obtained from the Richards equation. The availability of an explicit analytical expression for partial saturation will enable incorporation of the critical phenomenon of partial saturation in the design of paper microfluidic devices.

A Microfluidic Paper-Based Lateral Flow Device for Quantitative ELISA

This study presents an innovative lateral flow microfluidic paper-based analytical device (μPAD) designed for conducting quantitative paper-based enzyme-linked immunosorbent assays (p-ELISA), seamlessly executing conventional ELISA steps in a paper-based format. The p-ELISA device utilizes a passive fluidic circuit with functional elements such as a multi-bi-material cantilever (B-MaC) assembly, delay channels, and a buffer zone, all enclosed within housing for autonomous, sequential loading of critical reagents onto the detection zone. This novel approach not only demonstrates a rapid assay completion time of under 30 min, but also boasts reduced reagent requirements, minimal equipment needs, and broad applicability across clinical diagnostics and environmental surveillance. Through detailed descriptions of the design, materials, and fabrication methods for the multi-directional flow assay (MDFA), this manuscript highlights the device’s potential for complex biochemical analyses in a user-friendly and versatile format. Analytical performance evaluation, including a limit of detection (LOD) of 8.4 pM for Rabbit IgG, benchmarks the device’s efficacy compared to existing p-ELISA methodologies. This pioneering work lays the groundwork for future advancements in autonomous diagnostics, aiming to enhance global health outcomes through accessible and reliable testing solutions.

Spatial and temporal detection of root exudates with a paper-based microfluidic device

Root exudates control critical processes in the rhizosphere, retaining water, selecting for beneficial microorganisms or solubilising nutrients prior to uptake by the plant. Analysing root exudation patterns however is challenging because existing methods are often destructive and unable to resolve spatial and temporal variations in the production of root exudates. Here, we present a paper-based microfluidic device with integrated colorimetric sensors for the continuous extraction and analysis of root exudates along plant roots. The microfluidic device used standard filter paper wax printer to create channels for water to carry the exudates towards the sensors. TiO2 nanotubes/alginate hydrogel-based sensors were used to analyse the glucose content of the root exudates of living plants. The study shows that the paper microfluidic substrate successfully extracts the released glucose from the root, and transfers it to the hydrogel-based sensor to be colorimetrically detected from independent sections of the root at different times, up to 7 days. This method was tested on two different wheat varieties Triticum aestivum (rgt Tocayo and Filon varieties), where significant differences in exudation patterns were recorded. This research demonstrates the feasibility of low-cost technological solution for high precision screening and diagnostic of the biochemical composition of root exudates.

Distance-based qualitative determination of pyrophosphate ions with a Haus-made microfluidic paper-based device using the metal–organic framework NH2-MIL-88 (Fe)

This study initially reports a distance-based quantitative assay of pyrophosphate ion (PPi) based on analyte-triggered decomposition of metal–organic framework (MOF) in microfluidic paper-based analytical devices (µPADs). The µPADs were created using a mini-cutter machine and a home-use hot-pressing machine for loading one type of MOF of NH2-MIL-88 (Fe) prepared with Fe3+ and fluorescent ligand of 2-aminoterephthalic acid (NH2-BDC). Upon sample introduction, the PPi could compete with NH2-BDC to bind Fe3+, leading to disintegration of the MOF and releasing of the fluorescent ligand in paper channel. The length (distance) of the NH2-BDC’s flow trace, when irradiated by a money tester pen, is proportional to the PPi level. The results show that the developed method only requires a ruler to linearly quantify PPi in a concentration range of 0–1000 μM, with a limit estimated to be ∼0.25 μM. Furthermore, recovery of PPi in orange juice and human urine was between 95.72 and 108.11 %, further validating its high detection accuracy. The fabrication method for µPADs offers many attractive advantages kike simplicity, batch production capability and low cost. Moreover, to our knowledge, this may be the first report of a portable quantitative MOF-based PPi assay with distance-based readout in µPADs.

Laser-printed paper ELISA and hydroxyapatite immobilization for colorimetric congenital anomalies screening in saliva

BackgroundAlpha-fetoprotein (AFP) is a fetal protein that can indicate congenital anomalies such as Down syndrome and spinal canal blockage when detected at abnormal levels in pregnant women. Current AFP detection methods rely on invasive blood or serum samples, which require sophisticated equipment. From the many solutions proposed, colorimetric paper-based assays excel in point-of-care settings. The concept of paper-based ELISA (p-ELISA) enhances traditional methods, aligning with the ASSURED criteria for diagnostics in resource-limited regions. Despite success in microfluidic paper-based assay devices, laser printing remains underexplored for p-ELISA. Additionally, modifying the paper surface provides an additional layer of sensitivity enhancement. ResultsIn this study, we developed a novel laser-printed paper-based ELISA (LP-pELISA) for rapid, sensitive, and noninvasive detection of AFP in saliva samples. The LP-pELISA platform was fabricated by printing hydrophobic barriers on filter paper using a laser printer, followed by depositing hydroxyapatite (HAp) as an immobilization material for the antibodies. The colorimetric detection was achieved using AuNPs functionalized with anti-AFP antibodies and silver nitrate enhancement. The LP-pELISA exhibited a linear response for AFP detection in both buffer and saliva samples over a range of 1.0–800 ng mL−1, with a limit of detection (LOD) reaching 1.0 ng mL−1. The assay also demonstrated good selectivity, repeatability, reproducibility, and stability. The LP-pELISA was further validated by testing spiked human saliva samples, showing its potential for point-of-care diagnosis of congenital disabilities. SignificanceThe LP-pELISA is a noninvasive platform showcasing simplicity, cost-effectiveness, and user-friendliness, utilizing laser printing, hydroxyapatite modification, and saliva samples to efficiently detect AFP. Beyond its application for AFP, this method's versatility extends to other biomarkers, positioning it as a catalyst for the evolution of paper-based biosensors. The LP-pELISA holds promise as a transformative tool for point-of-care diagnostics, fostering advancements in healthcare with its innovative technology.

Automatic offline-capable smartphone paper-based microfluidic device for efficient biomarker detection of Alzheimer's disease

BackgroundAlzheimer's disease (AD) is a prevalent neurodegenerative disease with no effective treatment. Efficient and rapid detection plays a crucial role in mitigating and managing AD progression. Deep learning-assisted smartphone-based microfluidic paper analysis devices (μPADs) offer the advantages of low cost, good sensitivity, and rapid detection, providing a strategic pathway to address large-scale disease screening in resource-limited areas. However, existing smartphone-based detection platforms usually rely on large devices or cloud servers for data transfer and processing. Additionally, the implementation of automated colorimetric enzyme-linked immunoassay (c-ELISA) on μPADs can further facilitate the realization of smartphone μPADs platforms for efficient disease detection. ResultsThis paper introduces a new deep learning-assisted offline smartphone platform for early AD screening, offering rapid disease detection in low-resource areas. The proposed platform features a simple mechanical rotating structure controlled by a smartphone, enabling fully automated c-ELISA on μPADs. Our platform successfully applied sandwich c-ELISA for detecting the β-amyloid peptide 1–42 (Aβ 1–42, a crucial AD biomarker) and demonstrated its efficacy in 38 artificial plasma samples (healthy: 19, unhealthy: 19, N = 6). Moreover, we employed the YOLOv5 deep learning model and achieved an impressive 97 % accuracy on a dataset of 1824 images, which is 10.16 % higher than the traditional method of curve-fitting results. The trained YOLOv5 model was seamlessly integrated into the smartphone using the NCNN (Tencent's Neural Network Inference Framework), enabling deep learning-assisted offline detection. A user-friendly smartphone application was developed to control the entire process, realizing a streamlined “samples in, answers out” approach. SignificanceThis deep learning-assisted, low-cost, user-friendly, highly stable, and rapid-response automated offline smartphone-based detection platform represents a good advancement in point-of-care testing (POCT). Moreover, our platform provides a feasible approach for efficient AD detection by examining the level of Aβ 1–42, particularly in areas with low resources and limited communication infrastructure.

One-drop micro-array towards accelerated optical quantification of dopamine in human biofluids using triangular silver nanoparticles: Smartphone-assisted biomedical analysis by colorimetric sensing and Lab-on-paper technology

Trace-level detection of Dopamine (DA) in human body fluids is crucial for diagnosing neurological disorders, understanding mental health, and advancing drug discovery, but found challenging with rapid and low-cost detection technologies. Herein, an innovative paper-based photochemical method has been developed for the detection of DA using triangular silver nanoprism (AgNPrs), as an optical nanoprobe, in human blood plasma and urine samples. The redox reaction between DA and AgNPrs was evaluated through a color change at two pHs (5.35and 6.14), which can be analyzed by UV–Vis spectrophotometry and microfluidic paper-based colorimetric device (µPCD) with low limit of quantification of 0.01 µM. This study presents pioneering work with the potential to inspire the development of simple and effective on-site semi quantifying recognition devices for other neurotransmitters, requiring only a lightweight piece of paper and a single drop of the necessary reagent.

Paper-based Microfluidic Devices for the Analysis of Various Pathogens from Diverse Samples

Abstract: In today’s era, detection of disease is utmost important for the management of disease. Early detection leads to early management of disease. Paper-based microfluidic devices are promising technologies that are cost-effective, portable and easy to use over conventional methods. In addition, paper-based microfluidics offers low reagent/sample volume, less response time and can be used in resource-limited settings. Researchers are highly fascinated by this technology as it has a lot of potential to convert into commercial monitoring devices. The present article covers the uses of paper-based microfluidic technology for the swift and sensitive detection of pathogens from diverse samples, viz. food, water and blood. In this comprehensive review, paper-based microfluidic devices are introduced, including the basic concepts, current status and applications, along with the discussion of the limitations of microfluidics for the detection of pathogens. Although paper-based microfluidic devices are being developed, their commercialization requires simplification of manufacturing processes, reduction in production costs as well as an increase in production efficiency. Nonetheless, the integration of artificial intelligence (AI) and the Internet of Things (IoT) like smartphones, digital cameras, webcam etc. with paper-associated diagnosis has transformed the point-of-care (POC) diagnostics.

Microfluidic paper-based analysis device applying black phosphorus nanosheets@MWCNTs-COOH: A portable and efficient strategy for detection of β-Lactoglobulin in dairy products

This study prepared a novel, portable and cost-effective microfluidic paper-based electrochemical analysis device (μ-PAD) using black phosphorus nanosheets@carboxylated multi-walled carbon nanotubes (BPNSs@MWCNTs-COOH) nanocomposites for β-lactoglobulin (β-LG) detection. At the appreciate ratio, the synthesized BPNSs@MWCNTs-COOH was demonstrated to not only serve as a high-quality substrate for the specific aptamer immobilization, but also improve the electron transfer capability of the sensing interface. The μ-PADs, utilizing BPNSs@MWCNTs-COOH and aptamer recognition, exhibited a wider detection range (10–1000 ng mL−1) and lower detection limit (LOD: 0.12 ng mL−1) for β-LG, and demonstrated enhanced specificity, satisfactory anti-interference ability and stability. When applied to the β-LG determination in dairy samples, the μ-PAD yielded β-LG concentrations highly correlated with those obtained using the HPLC method (R2: 0.9982). These results emphasized the reliable performance of the developed μ-PADs in β-LG allergen quantification, highlighting their potential as an efficient platform for the rapid screening of β-LG allergens.

Microfluidic Paper-Based Device Incorporated with Silica Nanoparticles for Iodide Quantification in Marine Source Dietary Supplements.

Iodine is an essential micronutrient for humans due to its fundamental role in the biosynthesis of thyroid hormones. As a key parameter to assess health conditions, iodine intake needs to be monitored to ascertain and prevent iodine deficiency. Iodine is available from various food sources (such as seaweed, fish, and seafood, among others) and dietary supplements (multivitamins or mineral supplements). In this work, a microfluidic paper-based analytical device (μPAD) to quantify iodide in seaweed and dietary supplements is described. The developed μPAD is a small microfluidic device that emerges as quite relevant in terms of its analytical capacity. The quantification of iodide is based on the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by hydrogen peroxide in the presence of iodine, which acts as the catalyst to produce the blue form of TMB. Additionally, powder silica was used to intensify and uniformize the colour of the obtained product. Following optimization, the developed μPAD enabled iodide quantification within the range of 10-100 µM, with a detection limit of 3 µM, and was successfully applied to seaweeds and dietary supplements. The device represents a valuable tool for point-of-care analysis, can be used by untrained personnel at home, and is easily disposable, low-cost, and user-friendly.

Development and validation of spectrophotometric method and paper-based microfluidic devices for the quantitative determination of Amoxicillin in pure form and pharmaceutical formulations

There is a growing need for easy-to-use, low cost and portable quantitative assays to determine active pharmaceutical ingredients in the pharmaceutical industry. Here, we developed a batch spectrophotometric method and a method employing a paper-based microfluidic device for the estimation of Amoxicillin (AMX) in pure solution and pharmaceutical preparations. The detection depends on the coupling reaction of Amoxicillin with diazotized sulfadimidine (DSDM) in an alkaline medium. The yellow azo dye reaction product was measured at λmax 425 nm and linearity was observed from 2 to 30 mg L−1 with a detection limit of 0.32 mg L−1 and a quantification limit of 1.2 mg L−1 was found. The reaction was then transferred onto the paper-based microfluidic device and a plateau change in color intensity was found above 10 mg L−1. Thus, the paper-based microfluidic device can be applied for the semi-quantitative determination of Amoxicillin in pure solution and commercial pharmaceutical products for rapid screening.

Thermally programmable time delay switches for multi-step assays in paper-based microfluidics

Paper-based microfluidic devices offer advantages such as low cost and disposability for point-of-care diagnostic applications. However, actuation of fluids on paper can be a challenge in multi-step and complex assays. In this work, a thermally programmable time-delay switch (TPTDS) is presented which operates by causing delays in the fluid path of a microfluidics paper-based analytical device (μPAD) by utilizing screen-printed wax micro-bridges. The time-delay is achieved through an electrical power feedback loop which indirectly adjusts the temperature of each individual micro-bridge, melting the wax into the paper. The melted wax manipulates the fluid flow depending on its penetration depth into the paper channel, which is a function of the applied temperature. To demonstrate functionality of the proposed method, the TPTDS is employed to automate and perform the nitrate assay which requires sequential delivery of reagents. Colorimetric detection is used to quantify the results by utilizing an electronic color sensor.

Origami Paper-Based Electrochemical Immunosensor with Carbon Nanohorns-Decorated Nanoporous Gold for Zearalenone Detection

Nowadays, mycotoxin contamination in cereals and wastewater exposes a safety hazard to consumer health. This work describes the design of a simple, low-cost, and sensitive origami microfluidic paper-based device using electrochemical detection for zearalenone determination. The microfluidic immunosensor was designed on a paper platform by a wax printing process. The graphitized carbon working electrode modified with carbon nanohorns-decorated nanoporous gold showed a higher surface area, sensitivity, and adequate analytical performance. Electrodes were characterized by scanning electron microscopy, energy-dispersive spectroscopy, and cyclic voltammetry. The determination of zearalenone was carried out through a competitive immunoassay using specific antibodies immobilized by a covalent bond on the electrode surface. In the presence of HRP-labeled enzyme conjugate, substrate, and catechol, zearalenone was detected employing the developed immunosensor by applying −0.1 V to the working electrode vs silver as a pseudo-reference electrode. A calibration curve with a linear range between 10 and 1000 µg Kg−1 (R2 = 0.998) was obtained, and the limit of detection and quantification for the electrochemical immunosensor were 4.40 and 14.90 µg Kg−1, respectively. The coefficient of variation for intra- and inter-day assays was less than 5%. The selectivity and specificity of the sensor were evaluated, comparing the response against zearalenone metabolites and other mycotoxins that could affect the corn samples. Therefore, origami is a promising approach for paper-based electrochemical microfluidic sensors coupled to smartphones as a rapid and portable tool for in situ mycotoxins detection in real samples.

One-drop chemosensing of dapoxetine hydrochloride using opto-analysis by multi-channel μPAD decorated silver nanoparticles: introducing a paper-based microfluidic portable device/sensor toward naked-eye pharmaceutical analysis by lab-on-paper technology.

Dapoxetine (DPX) belongs to the selective serotonin reuptake inhibitor (SSRI) class and functions by blocking the serotonin transporter and increasing serotonin activity, thereby delaying ejaculation. Therefore, monitoring of the concentration of DPX in human biofluids is important for clinicians. In this study, application of silver nanoparticles with the morphology of prisms (AgNPrs) for the sensitive measurement of DPX using colorimetric chemosensing and the spectrophotometric method was investigated. Also, DPX was determined in real samples using the spectrophotometry method. Based on the obtained results, all of the detection process in colorimetric assay is related to morphological reform of AgNPrs after it's specific electrostatic and covalent interaction with DPX as analyte. The UV-vis results indicate that the proposed AgNPrs-based chemosensing system has a wide range of linearity (0.01 μM to 1 mM) with a low limit of quantification of 0.01 μM in human urine samples, which is suitable for clinical analysis of this drug in human urine samples. It is important to point out that, this chemosensing strategy showed inappropriate analytical results for the detection of DPX in human urine samples which is a novelty of this platform. Finally, the optimized microfluidic paper-based analytical device (μPAD) was integrated with the colorimetric analysis of DPX to provide a time/color system for estimating analyte concentration by a portable substrate toward in situ and on-site biomedical analysis. Interestingly, the analytical validation tests showed appropriate results with great stability, which may facilitate commercialization of the engineered substrate. For the first time, in order to provide a simple and portable colorimetric/spectrophotometric recognition system to sensitive determination of DPX, an optimized pump-less microfluidic paper-based colorimetric device (μPCD) was introduced and validated for the real-time biomedical analysis of this analyte. According to the obtained results, this alternative approach is suitable for therapeutic drug monitoring (TDM) and biomedical analysis by miniaturized and cost-beneficial devices.

Plasmonic silver and gold nanoparticles: shape- and structure-modulated plasmonic functionality for point-of-caring sensing, bio-imaging and medical therapy.

Silver and gold nanoparticles have found extensive biomedical applications due to their strong localized surface plasmon resonance (LSPR) and intriguing plasmonic properties. This review article focuses on the correlation among particle geometry, plasmon properties and biomedical applications. It discusses how particle shape and size are tailored via controllable synthetic approaches, and how plasmonic properties are tuned by particle shape and size, which are embodied by nanospheres, nanorods, nanocubes, nanocages, nanostars and core-shell composites. This article summarizes the design strategies for the use of silver and gold nanoparticles in plasmon-enhanced fluorescence, surface-enhanced Raman scattering (SERS), electroluminescence, and photoelectrochemistry. It especially discusses how to use plasmonic nanoparticles to construct optical probes including colorimetric, SERS and plasmonic fluorescence probes (labels/reporters). It also demonstrates the employment of Ag and Au nanoparticles in polymer- and paper-based microfluidic devices for point-of-care testing (POCT). In addition, this article highlights how to utilize plasmonic nanoparticles for in vitro and in vivo bio-imaging based on SERS, fluorescence, photoacoustic and dark-field models. Finally, this article shows perspectives in plasmon-enhanced photothermal and photodynamic therapy.

Acoustofluidics-Assisted Multifunctional Paper-Based Analytical Devices.

Microfluidic paper-based analytical devices (μPADs) feature an economic and sensitive nature, while acoustofluidics displays contactless and versatile virtue, and both of them gained tremendous interest in the past decades. Integrating μPADs with acoustofluidic techniques provides great potential to overcome the inherent shortcomings and make appealing achievements. Here, we present acoustofluidics-assisted multifunctional paper-based analytical devices that leverage bulk acoustic waves to realize multiple applications on paper substrates, including uniform colorimetric detection, microparticle/cell enrichment, fluorescence amplification, homogeneous mixing, and nanomaterial synthesis. The glucose detection in the range of 5-15 mM was conducted to perform uniform colorimetric detection. Various types (brass powder, copper powder, diamond powder, and yeast cells) and sizes (5-200 μm) of solid particles and biological cells can be enriched on paper in a few seconds or minutes; thus, fluorescence amplification by 3 times was realized with the enrichment. The high-throughput and homogeneous mixing of two fluids can be achieved, and based on the mixing, nanomaterials (ZnO nanosheets) were synthesized on paper. We analyzed the underlying mechanisms of these applications in the devices, which are attributed to Faraday waves and Chladni patterns. With their simple fabrication and prominent effectiveness, the devices open up new possibilities for paper-based microfluidic devices.

Soft Epidermal Paperfluidics for Sweat Analysis by Ratiometric Raman Spectroscopy.

The expanding interest in digital biomarker analysis focused on non-invasive human bodily fluids, such as sweat, highlights the pressing need for easily manufactured and highly efficient soft lab-on-skin solutions. Here, we report, for the first time, the integration of microfluidic paper-based devices (μPAD) and non-enhanced Raman-scattering-enabled optical biochemical sensing (Raman biosensing). Their integration merges the enormous benefits of μPAD, with high potential for commercialization and use in resource-limited settings, with biorecognition-element-free (but highly selective) optical Raman biosensing. The introduced thin (0.36 mm), ultra-lightweight (0.19 g), and compact footprint (3 cm2) opto-paperfluidic sweat patch is flexible, stretchable, and conforms, irritation-free, to hairless or minimally haired body regions to enable swift sweat collection. As a great advantage, this new bio-chemical sensory system excels through its absence of onboard biorecognition elements (bioreceptor-free) and omission of plasmonic nanomaterials. The proposed easy fabrication process is adaptable to mass production by following a fully sustainable and cost-effective process utilizing only basic tools by avoiding typically employed printing or laser patterning. Furthermore, efficient collection and transportation of precise sweat volumes, driven exclusively by the wicking properties of porous materials, shows high efficiency in liquid transportation and reduces biosensing latency by a factor of 5 compared to state-of-the-art epidermal microfluidics. The proposed unit enables electronic chip-free and imaging-less visual sweat loss quantification as well as optical biochemical analysis when coupled with Raman spectroscopy. We investigated the multimodal quantification of sweat urea and lactate levels ex vivo (with syntactic sweat including +30 sweat analytes on porcine skin) and achieved a linear dynamic range from 0 to 100 mmol/L during fully dynamic continuous flow characterization.

(Invited) Optical Paper-Based Microfluidic Devices for Point-of-Care Testing

Colorimetric paper-based microfluidic devices are well known for point-of-care testing of pregnancy and COVID-19 infection. However, colorimetric transduction makes devices low-sensitivity and poor resistance to interference of biomolecules in complex sample matrices. This presentation will discuss how to use utilize fluorescence and surface-enhanced Raman scattering to improve sensitivity and resistance to background interference.

A smartphone enabled low-cost portable centrifuge integrated with a simple paper-based device for the estimation of plasma-albumin concentration

We are developing a simple, affordable, and biodegradable microfluidic paper-based device (µPAD) for measuring albumin levels using 25 µL of human blood. First, we separate plasma from 25 µL of blood using a portable rotating device. Further, we gently deposit 10 µL of plasma into the µPAD, which is already coated and dried with 8 µL (0.004 M) of Bromothymol blue (BTB). The albumin in the plasma reacts with BTB, and consequently, the color of the detection zone changes from yellow to blue. We use a smartphone to capture the resulting image, and we quantify the albumin level with the help of an in-house developed app (ALB-SENSE). We are comparing the level of albumin measured with the recent device with the gold-standard results, and we observe a strong correlation (R2 = 0.9834) between the two values. In a nutshell, the device for plasma-albumin estimation through a colorimetric assay has true potential for its deployment as a point-of-care device with the involvement of minimally trained human resources in resource-constrained settings where healthcare diagnostic facilities are scarce. Statement of NoveltyThe measurement of albumin concentration is performed to figure out various diseases such as kidney damage, liver disease, malabsorption, diarrhoea, eclampsia, and nephrosis. Though clinical assays in gold standard devices as well as miniaturized microfluidic platforms are available for the measurement of plasma albumin, these assays suffer from one or more of the following major shortcomings: (i) complex fabrication and device integration, (ii) less efficacy in blood-plasma separation technique, (iii) Clinical assays are expensive and time-consuming, (iv) involvement of highly skilled technicians, and (v) non-availability of the smartphone app for HSA level measurement.Overcoming the constraints mentioned above, herein, we have developed a hybrid platform to estimate the albumin concentration. Our platform consists of a potable centrifugal device to separate blood plasma with high purity and a paper-based device to detect albumin concentration using an in-house developed app, “ALB-SENSE”. The gold-standard clinical assay has been translated in this miniaturized platform without sacrificing its fundamental principle for the determination of plasma-albumin level from the whole human blood, aiming to deploy our hybrid platform with ALB-SENSE app as a perfect candidate for field measurement of plasma-albumin, which would have the greatest possible impact on reducing the burden of above-mentioned disease among the underserved population.

Paper-based microfluidic electro-analytical device (PMED) for magneto-assay automation: Towards generic point-of-care diagnostic devices.

Rapid diagnostic tests (RDTs) for point-of-care (POC) testing of infectious diseases are popular because they are easy to use. However, RDTs have limitations such as low sensitivity and qualitative responses that rely on subjective visual interpretation. Additionally, RDTs are made using paper-bound reagents, which leads to batch-to-batch variability, limited storage stability and detection of only the analytes they were designed for. This work presents the development of a versatile technology, based on short magneto-assays and inexpensive paper-based microfluidic electro-analytical devices (PMEDs). PMEDs were produced locally using low-cost equipment, they were stable at room temperature, easy to use, and provided quantitative and objective results. The devices served to detect alternatively a variety of magneto-assays, granting quantitation of streptavidin-HRP, biotinylated HRP and Pasmodium falciparum lactate dehydrogenase (Pf-LDH) in less than 25 min, using either commercial or customized screen-printed electrodes and measurement equipment. Furthermore, Pf-LDH detection in diluted lysed whole blood displayed a linear response between 3 and 25 ng mL−1, detection and quantification limits ranging between 1 and 3 ng mL−1 and 6–12 ng mL−1, respectively, and provided results that correlated with those of the reference ELISA. In short, this technology is versatile, simple, and highly cost-effective, making it perfect for POC testing.