Explore the vast range of titles available.

This paper presents a fully automated microfluidic paper-based device for rapid detection of African swine fever virus (ASFV) and pseudorabies virus (PRV) using recombinase polymerase amplification (RPA). To address limitations of conventional paper-based RPA systems—including slow reagent transport due to viscous polymer additives (e.g., PEG) and manual intervention—we developed a self-contained μPAD featuring a programmable rotary valve and surface-modified channels. Oxygen plasma treatment combined with PVP (Polyvinylpyrrolidone) coating accelerated capillary flow by 64% (transfer time: 25 s vs. >80 s), while on-chip temperature control (42°C) and fluorescence detection enabled complete “sample-in, answer-out” operation. The device achieved detection limits of 5 copies/μL (ASFV) and 10 copies/μL (PRV) within 12–16 minutes, demonstrating a portable, instrument-free solution for point-of-care viral screening.

A wearable potentiometric device is reported based on an innovative butterfly-like paper-based microfluidic system, allowing for continuous monitoring of pH and Na + levels in sweat during physical activity. Specifically, the use of the butterfly-like configuration avoids evaporation phenomena and memory effects, enabling precise and timely biomarker determination in sweat. Two ad hoc modified screen-printed electrodes were embedded in the butterfly-like paper-based microfluidics, and the sensing device was further integrated with a portable and miniaturized potentiostat, leveraging Bluetooth technology for efficient data transmission. First, the paper-based microfluidic configuration was tested for optimal fluidic management to obtain optimized performance of the device. Subsequently, the two electrodes were individually tested to detect the two biomarkers, namely pH and Na + . The results demonstrated highly promising near-Nernstian (0.056 ± 0.002 V/dec) and super-Nernstian (− 0.080 ± 0.003 V/pH) responses, for Na + and pH detection, respectively. Additionally, several important parameters such as storage stability, interferents, and memory effect by hysteresis study were also investigated. Finally, the butterfly-like paper-based microfluidic wearable device was tested for Na + and pH monitoring during the physical activity of three volunteers engaged in different exercises, obtaining a good correlation between Na + increase and dehydration phenomena. Furthermore, one volunteer was tested through a cardiopulmonary test, demonstrating a correlation between sodium Na + increase and the energetic effort by the volunteer. Our wearable device highlights the high potential to enable early evaluation of dehydration and open up new opportunities in sports activity monitoring. Graphical abstract

Microfluidics found its place in point of care diagnostics. Microfluidic devices on paper substrate are proposed on both channel-based and digital microfluidics (DMF). But fluid flow controlling on microfluidics paper-based analytical devices (µPADs) and post-processing on DMF devices have limitations. In this work a new hybrid paper-based device is proposed with the aim of resolving these limitations and expanding the microfluidics capabilities in point of care diagnostics. The hybrid paper-based microfluidics (HPMF) device is composed of a DMF device following a µPAD in a single substrate, in which the DMF part performs the preprocessing steps of the test on droplets and transfers the resulting droplet to the µPAD part of the device for post-processing steps. The fabrication process of the device is rapid and very low cost due to use of paper substrate and out of clean-room processes. The results show that the proposed HPMF device can perform droplet operations: moving, mixing, and splitting.

This work presents an affordable distance-based microfluidic paper-based device (μPAD), using polydiacetylene (PDA) liposome as a chromogenic substance with a smartphone-based photo editor, for rapid and in-field analysis of quaternary ammonium compounds (QACs) (e.g., didecyldimethylammonium chloride (DDAC), benzyldimethyltetradecyl ammonium chloride (BAC), and cetylpyridinium chloride (CPC)). In-field analysis of these compounds is important to ensure their antimicrobial activity and user safety since they are widely utilized as disinfectants in households and hospitals. The μPAD featured a thermometer-like shape consisting of a sample reservoir and a microchannel as the detection zone, which was pre-deposited with PDA liposome. The color change from blue to red appeared in the presence of QACs and the color bar lengths were proportional to the QAC concentrations. Reactions of QACs with the PDA required a specific pH range (from pH 4.0 to 10.0) and a readout time of 7 min. Analytical performance characteristics of the device were tested with DDAC, BAC, and CPC showing acceptable specificity, accuracy (96.1–109.4%), and precision (%RSDs ≤ 9.3%). Limits of detection and quantitation were in the ranges of 20 to 80 and 70 to 250 μM, respectively. Feasibility of the newly developed device was demonstrated for in-field analysis of QACs in fumigation solution providing comparable results with those obtained from a colorimetric assay (P > 0.05). The proposed device shows potentials for further applications of other analytes since it offers speed, simplicity, and affordability for in-field analysis, especially in remote areas where expertise, resources, and infrastructures are limited.

Microfluidics is very crucial in lab-on-a-chip systems for carrying out operations in a large-scale laboratory environment on a single chip. Microfluidic systems are miniaturized devices in which the fluid behavior and control can be manipulated on a small platform, with surface forces on the platform being greater than volumetric forces depending on the test method used. In recent years, paper-based microfluidic analytical devices (μPADs) have been developed to be used in point-of-care (POC) technologies. μPADs have numerous advantages, including ease of use, low cost, capillary action liquid transfer without the need for power, the ability to store reagents in active form in the fiber network, and the capability to perform multiple tests using various measurement techniques. These benefits are critical in the advancement of paper-based microfluidics in the fields of disease diagnosis, drug application, and environment and food safety. Cancer is one of the most critical diseases for early detection all around the world. Detecting cancer-specific biomarkers provides significant data for both early diagnosis and controlling the disease progression. μPADs for cancer biomarker detection hold great promise for improving cure rates, quality of life, and minimizing treatment costs. Although various types of bioanalytical platforms are available for the detection of cancer biomarkers, there are limited studies and critical reviews on paper-based microfluidic platforms in the literature. Hence, this article aims to draw attention to these gaps in the literature as well as the features that future platforms should have.

This paper describes the design and construction of dual microfluidic paper–based analytical devices (dual-μPADs) as a lab-on-paper platform involving a “do-it-yourself” fabrication protocol. The device comprises a colorimetric and electrochemical module to obtain a dual-mode signal readout sensing strategy. A 3D pen polymeric resin was used to prepare graphite carbon-based electrodes and hydrophobic barriers on paper substrates. The proposed carbon-based ink was employed to manufacture electrodes on paper based on a stencil-printing approach, which were further characterized by electrochemical and morphological analyses. The analytical performance of the dual-μPADs was simultaneously evaluated for lactate, pH, nitrite, and salivary amylase (sAA) analysis. To demonstrate the proof-of-concept, saliva samples collected from both healthy individuals and those with periodontitis were successfully tested to demonstrate the feasibility of the proposed devices. Samples collected from individuals previously diagnosed with periodontitis showed high levels of nitrite and sAA (> 94 μmol L−1 and > 610 U mL−1) in comparison with healthy individuals (≤ 16 μmol L−1 and 545 U mL−1). Moreover, periodontitis saliva resulted in acid solution and almost null lactate levels. Notably, this protocol supplies a simple way to manufacture dual-μPADs, a versatile platform for sensitive detecting of biomarkers in saliva playing a crucial role towards the point-of-care diagnosis of periodontal disease.

Paper-based microfluidic devices have emerged as simple yet powerful platforms for performing low-cost analytical tests. This paper reports a microfluidic paper-based electrochemical biosensor array for multiplexed detection of physiologically relevant metabolic biomarkers. Different from existing paper-based electrochemical devices, our device includes an array of eight electrochemical sensors and utilizes a handheld custom-made electrochemical reader (potentiostat) for signal readout. The biosensor array can detect several analytes in a sample solution and produce multiple measurements for each analyte from a single run. Using the device, we demonstrate simultaneous detection of glucose, lactate and uric acid in urine, with analytical performance comparable to that of the existing commercial and paper-based platforms. The paper-based biosensor array and its electrochemical reader will enable the acquisition of high-density, statistically meaningful diagnostic information at the point of care in a rapid and cost-efficient way.

Lateral flow assays (LFAs) have been introduced and developed over the last half century. This technology is widely used as a tool for diagnosis in several fields such as environment, food quality and healthcare. Point-of-care (POC) diagnosis using LFAs has been attracting attention of the research community, particularly aiming for the development of a platform that can evaluate of biological markers in bodily fluids such as saliva and urine. The existence of a disease or the pregnancy can be determined by a test device, before further investigation and medical treatment. LFAs make use of a disposable test strip, which can provide diagnosis result on the spot within minutes. Thus, LFAs is a promising alternative of preliminary diagnosis for laboratory instruments that are costly, time consuming and require trained personnel. This paper includes a brief overview of the conventional LFAs: material selection based on its roles and characteristics, working principles, fundamentals, applications, and design criteria. We mainly discuss the technical challenges in both engineering and biochemical aspects and recommends possible solutions. We identify current research trends and provide perspectives of advanced technologies for enhancing assay performance.

Here, we present the rational design of a pinwheel-shaped three-dimensional microfluidic paper-based analytical device (3D-μPAD) for specific, sensitive and multiplexed detection of heavy metals in coastal waters. A more homogeneous permeation of fluids along the chip than common design, even under unskilled performance, has been achieved by the elaborate chip design of the hydrostatic balancing inlet port and uniformly stressed reversible sealing. With the combination of ion imprinted polymer grafted CdTe quantum-dots and fluid accumulation pad, 4 metals (Cu2+, Cd2+, Pb2+, and Hg2+) in 1 analysis and 25-fold enrichment for each metal can be simultaneously performed within 20 min, with detection limits of 0.007–0.015 μg/L. It has the ability to selectively recognize these 4 metals in mixtures and immunizing to interferences from components found in coastal waters, which provided results that were in agreement with values gained from atomic absorption. The inexpensive and portable nature as well as the highly sensitive and flexible performance of the new developed 3D-μPAD could make it attractive as an on-site testing approach for marine environmental monitoring.

A 3D paper-based microfluidic device has been developed for colorimetric determination of selected heavy metals in water samples by stacking layers of wax patterned paper and double-sided adhesive tape. It has the capability of wicking fluids and distributing microliter volumes of samples from single inlet into affrays of detection zones without external pumps, thus a range of metal assays can be simply and inexpensively performed. We demonstrate a prototype of four sample inlets for up to four heavy metal assays each, with detection limits as follows: Cu (II) = 0.29 ppm, Ni(II) = 0.33 ppm, Cd (II) = 0.19 ppm, and Cr (VI) = 0.35 ppm, which provided quantitative data that were in agreement with values gained from atomic absorption. It has the ability to identify these four metals in mixtures and is immune to interferences from either nontoxic metal ions such as Na(I) and K(I) or components found in reservoir or beach water. With the incorporation of a portable detector, a camera mobile phone, this 3D paper-based microfluidic device should be useful as a simple, rapid, and on-site screening approach of heavy metals in aquatic environments. Figure ᅟ