Portable Microfluidic Platform Research Articles

A regenerable microfluidic device with integrated valves and thin-film photodiodes for rapid optimization of chromatography conditions

The optimization of chromatography operating conditions is a lengthy and demanding task that typically requires large volumes of reagents and costly dedicated equipment. In particular, the use of multimodal chromatography, in which multiple interaction groups co-exist in the same ligand, can make the optimization process even more challenging. Nevertheless, the interest in using this emerging type of ligands has been increasing due to the enhanced selectivity and stability demonstrated by multimodal ligands in the purification of several biopharmaceuticals and their lower cost compared to biological affinity ligands. In this work, we report the development of an integrated, regenerable and portable microfluidic platform for performing a rapid screening of chromatography conditions. This platform was tested for the capture of fluorophore-labeled monoclonal antibodies directly from a cell culture supernatant using a multimodal ligand (Capto MMC). Liquid insertion in the microfluidic device was controlled by pneumatically actuated embedded valves and chromatography cycles were monitored via fluorescence measurements using thin-film a-Si:H photodiodes aligned beneath the device. The regeneration of the chromatography micro-column (70 nL) was performed in the end of each cycle, providing repeatable results over several consecutive cycles. Different buffers were successively evaluated in cycles, each cycle having duration of about 3 min, and the different adsorption and elution kinetics were compared, allowing the rapid optimization of conditions to address the capture of the monoclonal antibody from complex media. Overall, a versatile, rapid and relatively inexpensive platform to perform screening studies was developed, providing a high degree of scalability.

A portable microfluidic platform for rapid molecular diagnostic testing of patients with myeloproliferative neoplasms

The ability to simultaneously detect JAK2 V617F and MPL W515K/L mutations would substantially improve the early diagnosis of myeloproliferative neoplasms (MPNs) and decrease the risk of arterial thrombosis. The goal of this study is to achieve a point of care testing platform for simultaneous analysis of major genetic alterations in MPN. Here, we report a microfluidic platform including a glass capillary containing polypropylene matrix that extracts genomic DNA from a drop of whole blood, a microchip for simultaneous multi-gene mutation screening, and a handheld battery-powered heating device. The µmLchip system was successfully used for point-of-care identification of the JAK2 V617F and MPL W515K/L mutations. The µmLchip assays were then validated by mutation analysis with samples from 100 MPN patients who had previously been analyzed via unlabeled probe melting curve analysis or real-time PCR. The results from the µmLchip were in perfect agreement with those from the other methods, except for one discrepant result that was negative in the unlabeled probe melting curve analysis but positive in the µmLchip. After T-A cloning, sequences of cloned PCR products revealed JAK2 V617F mutation in the sample. The portable microfluidic platform may be very attractive in developing point-of-care diagnostics for MPL W515K/L and JAK2 V617F mutations.

Detection of ESKAPE Bacterial Pathogens at the Point of Care Using Isothermal DNA-Based Assays in a Portable Degas-Actuated Microfluidic Diagnostic Assay Platform.

ABSTRACTAn estimated 1.5 billion microbial infections occur globally each year and result in ∼4.6 million deaths. A technology gap associated with commercially available diagnostic tests in remote and underdeveloped regions prevents timely pathogen identification for effective antibiotic chemotherapies for infected patients. The result is a trial-and-error approach that is limited in effectiveness, increases risk for patients while contributing to antimicrobial drug resistance, and reduces the lifetime of antibiotics. This paper addresses this important diagnostic technology gap by describing a low-cost, portable, rapid, and easy-to-use microfluidic cartridge-based system for detecting the ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) bacterial pathogens that are most commonly associated with antibiotic resistance. The point-of-care molecular diagnostic system consists of a vacuum-degassed microfluidic cartridge preloaded with lyophilized recombinase polymerase amplification (RPA) assays and a small portable battery-powered electronic incubator/reader. The isothermal RPA assays detect the targeted ESKAPE pathogens with high sensitivity (e.g., a limit of detection of ∼10 nucleic acid molecules) that is comparable to that of current PCR-based assays, and they offer advantages in power consumption, engineering, and robustness, which are three critical elements required for the point-of-care setting.IMPORTANCE This paper describes a portable system for rapidly identifying bacteria in resource-limited environments; we highlight the capabilities of the technology by detecting different pathogens within the ESKAPE collection, which cause nosocomial infections. The system is designed around isothermal DNA-based assays housed within an autonomous plastic cartridge that are designed with the end user in mind, who may have limited technological training. Displaying excellent sensitivity and specificity, the assay systems that we demonstrate may enable future diagnoses of bacterial infection to guide the development of effective chemotherapies and may have a role in areas beyond health where rapid detection is valuable, including in industrial processing and manufacturing, food security, agriculture, and water quality testing.

A portable paper-based microfluidic platform for multiplexed electrochemical detection of human immunodeficiency virus and hepatitis C virus antibodies in serum.

This paper presents a portable paper-based microfluidic platform for multiplexed electrochemical detection of antibody markers of human immunodeficiency virus (HIV) and hepatitis C virus (HCV) in serum samples. To our best knowledge, this is the first paper-based electrochemical immunosensing platform, with multiplexing and telemedicine capabilities, for diagnosing HIV/HCV co-infection. The platform consists of an electrochemical microfluidic paper-based immunosensor array (E-μPIA) and a handheld multi-channel potentiostat, and is capable of performing enzyme-linked immunosorbent assays simultaneously on eight samples within 20 min (using a prepared E-μPIA). The multiplexing feature of the platform allows it to produce multiple measurement data for HIV and HCV markers from a single run, and its wireless communication module can transmit the results to a remote site for telemedicine. The unique integration of paper-based microfluidics and mobile instrumentation renders our platform portable, low-cost, user-friendly, and high-throughput.

Portable Lab-on-PCB platform for autonomous micromixing

In this paper, an SU-8 portable microfluidic platform consisting on an on-chip impulsion system implemented for micromixing is reported. The use of pressurized air chambers and controlled microvalves allows the impulsion of fluidic samples for autonomous mixing, avoiding the use of external pumps and improving the portability. The platform is fabricated by combining Flame Retardant 4 as PCB substrate, copper for electric contacts and lines, and SU-8 for the microfluidic circuit, with integration of sensing components in mind. A specific Simulink model provides the most suitable parameters. It studies the dynamic of the activation and represents the transient behavior of a microfluidic circuit that uses the impulsion of pressurized air to move and mix two different reagents. The simulated behavior includes the effect of the channel and chambers dimensions, initial pressure and volume, and fluids properties. A complete realization of the proposed platform is demonstrated, proving its validity for the realization of microfluidic systems for portable applications.

Continuous flow generation of magnetoliposomes in a low-cost portable microfluidic platform.

We present a low-cost, portable microfluidic platform that uses laminated polymethylmethacrylate chips, peristaltic micropumps and LEGO® Mindstorms components for the generation of magnetoliposomes that does not require extrusion steps. Mixtures of lipids reconstituted in ethanol and an aqueous phase were injected independently in order to generate a combination of laminar flows in such a way that we could effectively achieve four hydrodynamic focused nanovesicle generation streams. Monodisperse magnetoliposomes with characteristics comparable to those obtained by traditional methods have been obtained. The magnetoliposomes are responsive to external magnetic field gradients, a result that suggests that the nanovesicles can be used in research and applications in nanomedicine.

Fast and reliable urine analysis using a portable platform based on microfluidic electrophoresis chips with electrochemical detection

A novel ready-to-use portable microfluidic platform was adapted for analysis of uric acid and related compounds in urine samples. Microfluidic devices, especially microchips electrophoresis (ME), are very attractive for clinical and pharmaceutical analysis. Thus, a novel portable and easy-to-handle instrument, HVStat (165 × 150 × 85 mm), based on microfluidic electrophoresis chips with amperometric detection was used for the determination of uric acid and interfering compounds (ascorbic acid, paracetamol, epinephrine…) in urine samples. Moreover, the microfluidic platform performance is controlled by a user-friendly PC interface (MicruX® Manager) especially designed for the use of microchips electrophoresis with electrochemical detection. The adapted analysis methodology at portable microfluidic platform allows the separation and detection of uric acid and related compounds in less than 90s with minimal sample pre-treatment. Thus, the uric acid is directly detected without previous enzymatic based-reactions or other complex pretreatment. The urine sample is simply diluted in the buffer solution and injected directly in the microchip where the uric acid is separated and detected at the platinum electrode of a SU-8/Pyrex microfluidic chip. The microfluidic chips were used for several analyses with a good performance and precision, decreasing drastically the cost and time per analysis. Thus, the complete microfluidic platform, including the main instrument, reusable holder and microchips, has been demonstrated as an excellent analytical tool for fast and reliable urine analysis.

Rapid identification of ESKAPE bacterial strains using an autonomous microfluidic device.

This article describes Bacteria ID Chips (‘BacChips’): an inexpensive, portable, and autonomous microfluidic platform for identifying pathogenic strains of bacteria. BacChips consist of a set of microchambers and channels molded in the elastomeric polymer, poly(dimethylsiloxane) (PDMS). Each microchamber is preloaded with mono-, di-, or trisaccharides and dried. Pressing the layer of PDMS into contact with a glass coverslip forms the device; the footprint of the device in this article is ∼6 cm2. After assembly, BacChips are degased under large negative pressure and are stored in vacuum-sealed plastic bags. To use the device, the bag is opened, a sample containing bacteria is introduced at the inlet of the device, and the degased PDMS draws the sample into the central channel and chambers. After the liquid at the inlet is consumed, air is drawn into the BacChip via the inlet and provides a physical barrier that separates the liquid samples in adjacent microchambers. A pH indicator is admixed with the samples prior to their loading, enabling the metabolism of the dissolved saccharides in the microchambers to be visualized. Importantly, BacChips operate without external equipment or instruments. By visually detecting the growth of bacteria using ambient light after ∼4 h, we demonstrate that BacChips with ten microchambers containing different saccharides can reproducibly detect the ESKAPE panel of pathogens, including strains of: Enterococcus faecalis, Enteroccocus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter aerogenes, and Enterobacter cloacae. This article describes a BacChip for point-of-care detection of ESKAPE pathogens and a starting point for designing multiplexed assays that identify bacterial strains from clinical samples and simultaneously determine their susceptibility to antibiotics.

Lab-on-a-display: a new microparticle manipulation platform using a liquid crystal display (LCD)

This paper reports a new portable microfluidic platform, “lab-on-a-display,” that microparticles are manipulated by optoelectronic tweezers (OET) on a liquid crystal display (LCD). The OET has been constructed by assembling a ground layer, a liquid chamber, and a photoconductive layer. Without lens or optical alignments, the LCD image directly forms virtual electrodes on the photoconductive layer for dielectrophoretic manipulation. The lab-on-a-display was first realized by a conventional monochromatic LCD module and a light source brighter than 5,000 lux. It was successfully applied to the programmable manipulation of 45 μm polystyrene beads; more than 100 particles were transported with an optical image-driven control, following the moving edge of the image at every moment. The effects of bead size and bias voltage on the manipulation speed were also investigated. Due to the portability and compatibility for disposable applications, this new platform has potential for programmable particle manipulation or chip-based bioprocessing including cell separation and bead-based analysis.