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Microfluidic systems can be used to control picoliter to microliter volumes in ways not possible with other methods of fluid handling. In recent years, the field of microfluidics has grown rapidly, with microfluidic devices offering possibilities to impact biology and medicine. Microfluidic devices populated with human cells have the potential to mimic the physiological functions of tissues and organs in a three-dimensional microenvironment and enable the study of mechanisms of human diseases, drug discovery and the practice of personalized medicine. In the field of otorhinolaryngology, various types of microfluidic systems have already been introduced to study organ physiology, diagnose diseases, and evaluate therapeutic efficacy. Therefore, microfluidic technologies can be implemented at all levels of otorhinolaryngology. This review is intended to promote understanding of microfluidic properties and introduce the recent literature on application of microfluidic-related devices in the field of otorhinolaryngology.

Slurry erosion is a common phenomenon found in fluid handling systems and processing industries. The components used in such systems and industries experience serious surface damage due to continuous interaction with flowing fluids. Hence, the components fall short to work of its lifetime. Selection of materials for such applications is a challenge for the designers. In this article, an attempt has been made to develop a slurry jet erosion test rig to evaluate such materials. Brass is used as the candidate material to evaluate the test rig with and without erodent. The material weight loss for different impingement angles is presented. Micrographs show the traces of erosion marks. These results are presented in the article to show the operation and performance of the test rig.

The shortage of fresh water resources is becoming more and more serious with the acceleration of modernization and industrialization, especially in some dry welding and underdeveloped areas. Scientists are bent on alleviating the issue of fresh water shortage. Concurrently, many biological species have developed elegant schemes for water-harvesting for their survival. Combining their mechanisms and design strategies is crucial to fabricate interfacial materials with efficient water collection. This paper extracts the water-collecting principles and characteristics of Namib Desert beetles, cactus and spider silk, and reviews the synthesis strategies of various bionic water collecting materials under the guidance of these typical creatures. We put an extreme emphasis on the liquid–solid interfacial interaction between the accumulative nuclear dew and functional materials' surfaces. The key factor for reliable water collection materials is the design of robust hierarchical configuration. However, these constructed microstructures are vulnerable and many practical applications are limited. Therefore, the design of architectures with durability has become a serious topic and we highlight the development, current research status on the durability and self-repair of directional water collection materials. Finally, a holistic view and future prospects of bionic directional water collection materials, including mechanisms, characterization, design strategies and fabrication techniques, are provided. We envision that these well-chosen facts and opinions will be useful in fluid handling and transportation, self-cleaning and water collection fields.

Paper is emerging as a versatile platform for automated fluid handling with a broad range of applications in medical diagnostics and analytical chemistry. However, selectively controlling analyte transport in paper to achieve concentration or selection has been a challenge for functional analysis. Here, by combining paper-based microfluidics with acoustics, we present a rapid and powerful method to size dependently control movement of microparticles and cells in paper using surface acoustic waves (SAW). We demonstrate the unique capability of the paper-based SAW approach to trap and concentrate microparticles in paper and release them when required, achieving collection efficiency of over 98%. Given the correlation between collection efficiency, size, and applied power, the paper-based SAW approach is applied to isolate a mixture of microparticles (1.1, 3.2, and 5 μm in diameter) into different regions and also to trap and concentrate human prostate cancer PC3 cells at a predetermined site. This paper-based SAW approach provides opportunities to develop powerful and low-cost selection and analysis tools, capable of processing complex multicomponent samples, with potential applications in medical diagnostics.

Regulating the fluid flow in microfluidic devices enables a wide range of assay protocols for analytical applications. A programmable, photo-paper-based microfluidic device fabricated by using a method of cutting and laminating, followed by printing, is reported. The flow distance of fluid in the photo-paper-based channel was linearly proportional to time. By printing silver nanoparticle (AgNP) and poly[4,5-difluoro-2,2-bis(trifluoromethyl)-1,3-dioxole-co-tetrafluoroethylene] (PTFE) patterns on the surface of a photo-paper-based channel, we were able to either increase or decrease the fluid flow in the fabricated microfluidic devices, while maintaining the linearity in the flow distance-time relation. In comparison to the speed of fluid flow in a pristine channel, by using hydrophilic AgNP patterns, we were able to increase the speed in the channel by up to 15 times while we were able to slow the speed by a factor of 3 when using hydrophobic PTFE dots. We then further demonstrated a single-step protocol for detecting glucose and a multi-step protocol for detecting methyl paraoxon (MPO) with our methods in photo-paper-based microfluidic devices. This approach can lead to improved fluid handling techniques to achieve a wide range of complex, but programmable, assays without the need for any additional auxiliary devices for automated operation.

Introduction: Superabsorbent foam (SAF) and superabsorbent polymer (SAP) dressings are compared on their abilities to handle moisture exuding from an artificial wound and to affect the microclimate...

Description, Miniaturized and soft magnetically levitated centrifugal pumps can handle various fluids for wearable applications., Centrifugal pumps are essential mechanical components for liquid delivery in many biomedical systems whose miniaturization can promote innovative disease treatment approaches. However, centrifugal pumps are predominately constructed by rigid and bulky components. Here, we combine the soft materials and flexible electronics to achieve soft magnetic levitation micropumps (SMLMs) that are only 1.9 to 12.8 grams in weight. The SMLMs that rotate at a rotation speed of 1000 revolutions per min to pump liquids with various viscosities ranging from 1 to 6 centipoise can be used in assisting dialysis, blood circulation, and skin temperature control because of excellent biocompatibility with no organ damage. The development of SMLMs not only demonstrates the possibility to replace rigid rotating structures with soft materials for handling large volumes of fluids but also indicates the potential for fully flexible artificial organs that may revolutionize health care and improve the well-being of patients.

Among the advanced wound dressing types, superabsorbent (SA) dressings form an important class of dressings, particularly for the management of medium to highly exuding wounds. However, SA dressings are not all made the same. This educational article describes distinct, common SA dressing designs, which differ fundamentally in structure and composition, and, thereby, in their exudate absorption function and clinical efficacy. The diverse design families of SA dressings, including dressings with an SA polymer-sheet core, versus dressings with an air laid core, where the SA polymer grains are embedded in fluff, relate to different manufacturing processes, production techniques and associated fabrication costs. These fundamental structural and material differences across SA dressing designs from different manufacturers naturally lead to wide variations in the fluid handling characteristics of the products, which are analysed here using both theoretical and experimental bioengineering laboratory approaches. This work is primarily aimed at promoting critical thinking among health professionals who should ask manufacturers to present relevant testing data for an informed clinical decision-making with regards to the choice of the safest and best performing SA dressing for each treated wound case.

Objective: A new test method is described which provides a convenient technique for assessing the combined effects of gravity and compression on the fluid handling characteristics of surgical dressing which can have important implications for their use in the treatment of venous ulcers. Simple ways of improving use of the fluid handling capacity of products currently used clinically are suggested, and the possibility of developing a dressing specifically designed to resist gravitational effects is discussed.

Microbiological environments are a clear application area for microscale robotics, but targeted delivery of biochemical cues to particular cells or tissues remains a significant challenge. This challenge is compounded by the sheer number of cells that compose tissues. Multirobot system development has been limited due to challenges in discrete operation of several robots in a confined space. Here, we demonstrate the use of multiple diamagnetically levitated robots for delivering biochemicals dissolved in liquid in a manner compatible with light microscopy. Specifically, we show loading, transport, and diffusive release of fluorescent molecules in hydrogels with microscale precision, as well as induction of synthetically engineered bacterial cells with signaling molecules. This platform holds potential for impact and utility in fields, such as developmental biology, tissue engineering, and synthetic biology.

Everything on earth is subject to physical laws, thus they influence all facets of living creatures. Although these laws restrain animals in many ways, some animals have developed a way to use physical phenomena in their favor to conserve energy. Many animals, which have to handle fluids, for example, have evolved passive mechanisms by adapting their wettability or using capillary forces for rapid fluid spreading. In distinct animals, a similar selection pressure always favors a convergent development. However, when assessing the biological tasks of passive fluid handling mechanisms, their diversity is rather surprising. Besides the well-described handling of water to facilitate drinking in arid regions, observed in, e.g., several lizards, other animals like a special flat bug have developed a similar mechanism for a completely different task and fluid: Instead of water, these bugs passively transport an oily defense secretion to a region close to their head where it finally evaporates. And again some spiders use capillary forces to capture prey, by sucking in the viscous waxy cuticle of their prey with their nanofibrous threads. This review highlights the similarities and differences in the deployed mechanisms of passive fluid handling across the animal kingdom. Besides including well-studied animals to point out different mechanisms in general, we stretch over to not as extensively studied species for which similar mechanisms are described for different tasks. Thus, we provide an extensive overview of animals for which passive fluid handling is described so far as well as for future inspiration.

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.

Microcalorimetry has been widely used to measure and characterize the heat change in phase transition, resolution mixing, and chemical/biochemical reactions. In this review, we discuss progress in the development of high-performance microfabricated calorimeters starting with their design, fluid handling, and temperature measurement. The considerations of chip design are highlighted. Then, a few representative applications are introduced and their chip parameters and properties are compared. Finally, trends and prospects of microcalorimeters for high-performance applications, such as enthalpy measurements in minute volumes of chemicals suitable for drug discovery as well as bio-applications in energy balance monitoring of living cells and investigation of their thermogenesis, are discussed.

Cellular therapies are creating a paradigm shift in the biomanufacturing industry. Particularly for autologous therapies, small-scale processing methods are better suited than the large-scale approaches that are traditionally employed in the industry. Current small-scale methods for manufacturing personalized cell therapies, however, are labour-intensive and involve a number of 'open events'. To overcome these challenges, new cell manufacturing platforms following a GMP-in-a-box concept have recently come on the market (GMP: Good Manufacturing Practice). These are closed automated systems with built-in pumps for fluid handling and sensors for in-process monitoring. At a much smaller scale, microfluidic devices exhibit many of the same features as current GMP-in-a-box systems. They are closed systems, fluids can be processed and manipulated, and sensors integrated for real-time detection of process variables. Fabricated from polymers, they can be made disposable, i.e. single-use. Furthermore, microfluidics offers exquisite spatiotemporal control over the cellular microenvironment, promising both reproducibility and control of outcomes. In this chapter, we consider the challenges in cell manufacturing, highlight recent advances of microfluidic devices for each of the main process steps, and summarize our findings on the current state of the art. As microfluidic cell culture devices have been reported for both adherent and suspension cell cultures, we report on devices for the key process steps, or unit operations, of both stem cell therapies and cell-based immunotherapies.

Point-of-care testing (POCT) is a specific format of diagnostic testing that is conducted without accompanying infrastructure or sophisticated instrumentation. Traditionally, such rapid sample-to-answer assays provide inferior analytical performances to their laboratory counterparts when measuring cardiac biomarkers. Hence, their potentially broad applicability is somewhat bound by their inability to detect clinically relevant concentrations of cardiac troponin (cTn) in the early stages of myocardial injury. However, the continuous refinement of biorecognition elements, the optimization of detection techniques, and the fabrication of tailored fluid handling systems to manage the sensing process has stimulated the production of commercial assays that can support accelerated diagnostic pathways. This review will present the latest commercial POC assays and examine their impact on clinical decision-making. The individual elements that constitute POC assays will be explored, with an emphasis on aspects that contribute to economically feasible and highly sensitive assays. Furthermore, the prospect of POCT imparting a greater influence on early interventions for medium to high-risk individuals and the potential to re-shape the paradigm of cardiovascular risk assessments will be discussed.

Chitosan films have been extensively studied as dressings in formulations for the treatment of chronic wounds. The incorporation of aloe vera (Aloe barbadensis Miller) into chitosan dressings could potentialize the healing process since aloe vera shows several pharmacological activities. This work aimed to evaluate the effect of aloe vera and chitosan concentrations on the physicochemical properties of the developed films. The films were obtained by casting technique and characterized with respect to their color parameters, morphology, barrier and mechanical properties, and thermal analysis. Results showed that the presence of aloe vera modified the films color parameters, changed barrier properties, increased fluid handling capacity (FHC), and decreased water-vapor permeability (WVP). The reduced elongation at break resulted in more rigid films. Aloe vera concentration did not significantly change film properties, but the presence of this gel increased the films stability at temperatures below 200 °C, showing similar behavior as chitosan films above 400 °C. The results suggest a crosslinking/complexation between chitosan and aloe vera, which combine appropriate physicochemical properties for application as wound dressing materials., This work was supported by São Paulo Research Foundation (FAPESP) (2010/17.721-4), Portuguese Science and Technology Foundation (FCT) through the projects M-ERA-NET/0004/2015 (PAIRED) and UIDB/04469/2020 (strategic fund) funded by national funds, and co-financed Education (FCT/MEC) from national funds and FEDER, under the Partnership Agreement PT202, info:eu-repo/semantics/publishedVersion

The recent outbreak of the novel coronavirus SARS-CoV-2, which causes COVID-19, can be diagnosed using RT-qPCR, but inadequate access to reagents and equipment has slowed disease detection and impeded efforts to mitigate viral spread. Alternative approaches based on combinations of isothermal amplification and CRISPR-mediated detection, such as the SHERLOCK (SpecificHighSensitivityEnzymaticReporter UnLOCKing) technique, offer reduced dependence on RT-qPCR equipment, but previously reported methods required multiple fluid handling steps, complicating their deployment outside clinical labs. Here we developed a simple test chemistry called STOP (SHERLOCK Testing in One Pot) for detecting SARS-CoV-2 in one hour that is suitable for point-of-care use. This simplified test, STOPCovid, provides sensitivity comparable to RT-qPCR-based SARS-CoV-2 tests and has a limit of detection of 100 copies of viral genome input in saliva or nasopharyngeal swabs per reaction. Using lateral flow readout, the test returns result in 70 minutes, and using fluorescence readout, the test returns result in 40 minutes. Moreover, we validated STOPCovid using nasopharyngeal swabs from COVID-19 patients and were able to correctly diagnose 12 positive and 5 negative patients out of 3 replicates. We envision that implementation of STOPCovid will significantly aid “test-trace-isolate” efforts, especially in low-resource settings, which will be critical for long-term public health safety and effective reopening of the society.

Large populations around the world suffer from numerous but treatable health issues, caused by either lifestyle choices or environmental factors. Over the past decades, point-of-care testing kits have been developed to circumvent the reliance on laboratories, by allowing users to perform preliminary health or environmental testing from the privacy of their homes. However, these kits heavily rely on the precision of the user to perform the procedures, leading to increased variability in final assessments. To eliminate user-induced errors, we present an integrated, completely sealed, and disposable point-of-care testing prototype that exploits the benefits of microfluidics and 3D-printing fabrication techniques. The palm-sized modular prototype consists of a manually operated fluid handling device that allows precise mixing, filtration, and delivery of fluids to an on-board microfluidic assay unit for subsequent detection of specific biochemical analytes, with a minimized risk of contamination.

Adhesives with improved fluid handling and stable mechanical properties are gaining increasing interest in wound care due to improved wound healing conditions. Silicone adhesives possess in general excellent oxygen permeability but poor liquid water absorption and transport due to their inherent hydrophobicity. Herein, we present a novel glycerol-silicone hybrid adhesive with improved fluid handling properties as a result of the incorporation of relatively monodisperse glycerol droplets distributed homogenously throughout the silicone adhesive. The discrete glycerol droplets promote water absorption when the adhesive comes into contact with an aqueous phase due to the hygroscopic nature of glycerol. Additionally, the adhesives' performance, evaluated in terms of mechanical properties, peel, and tack, is shown not to be compromised by presence of the glycerol droplets, mainly due to the so-called solid stiffening effect introduced by their interfacial energies.

Conformable, wearable biosensor-integrated systems are a promising approach to non-invasive and quantitative on-body detection of biomarkers in body fluids. However, realizing such a system has been slowed by the difficulty of fabricating a soft affinity-based biosensor patch capable of precise on-body fluid handling with minimal wearer intervention and a simple measurement protocol. Herein, we demonstrate a conformable, wearable lab-on-a-patch (LOP) platform composed of a stretchable, label-free, impedimetric biosensor and a stretchable microfluidic device for on-body detection of the hormone biomarker, cortisol. The all-in-one, stretchable microfluidic device can precisely collect and deliver sweat for cortisol quantitation and offers one-touch operation of reagent delivery for simultaneous electrochemical signal generation and washing. Three-dimensional nanostructuring of the Au working electrode enables the high sensitivity required to detect the pM-levels of cortisol in sweat. Our integrated LOP detected sweat cortisol quantitatively and accurately during exercise. This LOP will open a new horizon for non-invasive, highly sensitive, and quantitative on-body immunodetection for wearable personal diagnostics.

Microfluidic devices with integrated valves provide precise, programmable fluid handling platforms for high-throughput biological or chemical assays. However, setting up the infrastructure to control such platforms often requires specific engineering expertise or expensive commercial solutions. To address these obstacles, we present a Kit for Arduino-based Transistor Array Actuation (KATARA), an open-source and low-cost Arduino-based controller that can drive 70 solenoid valves to pneumatically actuate integrated microfluidic valves. We include a python package with a GUI to control the KATARA from a personal computer. No programming experience is required. Keywords: Python, Arduino shield, Open source hardware, Solenoid valve, Microfluidics, Multi-layer soft lithography

The onset of drainage of liquids from fluid-handling components with two or more orifices was evaluated. The components were filled with water, ethylene glycol, or ethyl alcohol and oriented vertically with their orifices facing downward. The lower end of the components was slowly raised toward the horizon. No flow occurred until a critical angle of inclination was reached. The resistance to drainage was greatest for small, closely spaced orifices and declined precipitously as the size and spacing of the orifices increased. The onset of drainage was successfully modeled as a balance between the hydrostatic pressure in the bulk liquid and the Laplace pressure of the air-liquid interfaces present within the orifices.

Paper-based analytical devices introduce an innovative platform technology for fluid handling andanalysis, with wide range of applications, promoting low cost, ease of fabrication/operation and equipment independence. This review gives a general overview on the fabrication techniques reported to date, revealing and discussing their weak points as well as the newest approaches in order to overtake current mass production limitations and therefore commercialisation. Moreover, this review aims especially to highlight novel technologies appearing in literature for the effective handling and controlling of fluids. The lack of flow control is the main problem of paper-based analytical devices, which generates obstacles for marketing and slows down the transition of paper devices from the laboratory into the consumers' hands. FBL acknowledges the Ram on y Cajal Programme (Ministerio de economía y Competitividad), Spain. FBL and TA acknowledge to Marian M. De Pancorbo for letting them to use her laboratory facilities at UPV/EHU. We acknowledge funding support from Gobierno de España, Ministerio de Economia y Competitividad, with Grant No. BIO2016-80417-P and from Gobierno Vasco, Dpto. Industria, Innovación, Comercio y Turismo under ELKARTEK 2017 with Grant No. KK-2017/0000088. L. B-D. acknowledges funding support from Basque Government, under "Grupos Consolidados" with Grant No. IT998-16.

The onset of drainage of liquids from fluid-handling components with a single, circular orifice was evaluated. A component was filled with water, ethylene glycol, or ethyl alcohol and then oriented vertically with its orifice facing downward. The lower end of the component was slowly tilted toward the horizon. No flow occurred until a critical angle of inclination was reached. The onset of drainage was successfully modeled as a balance between the hydrostatic pressure in the bulk liquid and the Laplace pressure of the air-liquid interface within the orifice. If the Laplace pressure was greater than the hydrostatic pressure, then the flow from the component was impeded. With further inclination, a critical angle was exceeded that allowed the liquid to flow from the component. The theoretical model gave reasonable estimates of the measured values.