Capillary-driven microfluidics: impacts of 3D manufacturing on bioanalytical devices

Azizian, Pooya; Casals‐Terré, Jasmina; Ricart, J.; Cabot, Joan M.

doi:10.1039/d3an00115f

Cited by 10 publications

(5 citation statements)

References 61 publications

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“…It locally decreases the magnitude of capillary pressure. Therefore, an abrupt enlargement in a microchannel can eliminate the driving net force and stop the flow [ 3 , 4 ]. For instance, a capillary flow within a smaller microchannel stops at the junction with a bigger microchannel.…”

Section: Resultsmentioning

confidence: 99%

“…At a trigger junction, after breaking the liquid–air meniscus until compelling the upstream retention and release, diffusive mixing of fluids’ molecules can lead to sample dilution, washing buffer contamination, and experiencing non-lateral flow patterns downstream [ 8 ]. A mediator gap filled by air can isolate the liquids to avoid these issues [ 4 ]. However, utilizing an air gap can later result in bubbles entering the circuit and microfluidic malfunction [ 8 ].…”

Section: Resultsmentioning

confidence: 99%

“…Miniaturization of diagnostic assays within microfluidic devices offers the benefit of using fewer reagent volumes, rapid and high-resolution analysis, cost effectiveness, and small footprints for the analytical devices [ 2 ]. Steering clear of the need for bulky and costly external instrumentation, capillary-driven microfluidics offers an on-chip fluid control approach suited for POC diagnostics [ 3 , 4 ]. Capillary-driven microfluidic devices control fluid flows spontaneously.…”

Section: Introductionmentioning

confidence: 99%

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Coupling Capillary-Driven Microfluidics with Lateral Flow Immunoassay for Signal Enhancement

Azizian,

Casals-Terré,

Guerrero-SanVicente

et al. 2023

Biosensors

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Microfluidics has emerged as a versatile technology that is applied to enhance the performance of analytical techniques, among others. Pursuing this, we present a capillary-driven microfluidic device that improves the sensitivity of lateral flow immunoassay rapid tests thanks to offering an automated washing step. A novel multilevel microfluidic chip was 3D-printed with a photocurable black resin, sealed by an optically clear pressure-sensitive adhesive, and linked to the lateral flow strip. To depict the efficacy of microfluidics and the washing step, cortisol was measured quantitatively within the proposed device. Measuring cortisol levels is a way to capture physiological stress responses. Among biofluids, saliva is less infectious and easier to sample than others. However, higher sensitivity is demanded because the salivary cortisol concentrations are much lower than in blood. We carried out a competitive lateral flow immunoassay protocol with the difference that the microfluidic device applies an automated washing step after the sample is drained downstream. It washes the trapped quantum-dot-labeled antibodies out from nitrocellulose, diminishing background noise as these are bonded to cortisols and not to the immobilized receptors. Fluorescence spectroscopy, as a high-precision analysis, was successfully applied to determine clinically relevant salivary cortisol concentrations within a buffer quantitatively. The microfluidic design relied on a 3D valve that avoids reagent cross-contamination. This cross-contamination could make the washing buffer impure and undesirably dilute the sample. The proposed device is cost-effective, self-powered, robust, and ideal for non-expert users.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Coupling Capillary-Driven Microfluidics with Lateral Flow Immunoassay for Signal Enhancement

Azizian,

Casals-Terré,

Guerrero-SanVicente

et al. 2023

Biosensors

Self Cite

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“…The R 1 is oriented against the ow direction and it counteracts the capillary pressure P 1 at the uid meniscus. [40]- [42] In analogy to the general micro uidic circuits that are based on the hydrophilic microchannel elements, [43] a hydrophilic textile generates a suction pressure at its wetting front, allowing for a ow with a velocity that is proportional to the pressure magnitude and reversely to the resistance. Once the rst module is lled with uid, it goes to the second one (Fig.…”

Section: Capillary Pressure Gradient Generationmentioning

confidence: 99%

Vertical textile epifluidics for integrated real-time electrochemical sweat analysis

Galliani

Azizian

Makhinia

et al. 2023

Preprint

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The non-invasive discovery of novel physiological biomarkers in sweat relies on its precise sampling and analysis. Here, we present a scalable fabrication approach of a wearable microfluidic system within fabric structures for an accurate and ergonomic sweat handling and sensing. Digital 3D printing of a flexible resin precisely defines impermeable microstructures in wicking textiles, only achievable by SLA technique. Regulated fluid collection, storage and transport, avoiding the complexity of traditional valves, is obtained by assembling 3D-printed textile-based modules in an origami-inspired vertical stack offering reduced device footprint, seamless and adhesive-free on-body sensing. The generation of pressure gradient across these microfluidic modules enables vertically distributed, capillary-driven and pre-programmed sweat flow. The tortuous flow characteristics of woven textile conduits based on the numerical fluid-dynamics simulation demonstrate the technological versatility to reproduce this controlled flow in different textile structures. The monolithic integration of textile microfluidics on garments provides unlimited, non-accumulative fluid flow through the extended air-liquid interface for its continuous flow and concomitant evaporation from the fabric surface. In-situ and in real-time sweat analysis with a remotely screen-printed flexible organic electrochemical transistor provides the possibility of various sensor integration and multi-parameter detections. The transistor successfully detects K+ ion concentrations using ion-selective membrane within the sweat physiological ionic range. This mechanically ergonomic, fabric-integrated microfluidic sensing platform, based on rapid additive manufacturing of polyhedral device configurations, offers unique strategies for device design and novel sensing perspectives for advancing wearable point-of-care diagnostics with personalized health monitoring capabilities.

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“…Addressing these limitations, our research introduces a passive device designed to match the processing capabilities of nitrocellulose-based systems while enabling cell analysis, offering a simpler, cost-effective solution for comprehensive blood diagnostics. Research has been conducted on improving the capillary action in biocompatible polymer microfluidic systems [ 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ]. Certain systems have been maximized in terms of the pumping efficiency without using nitrocellulose capillary pump structures [ 23 , 32 ].…”

Section: Introductionmentioning

confidence: 99%

Optimization of Microfluidics for Point-of-Care Blood Sensing

Tavakolidakhrabadi,

Stark,

Bacher

et al. 2024

Biosensors

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Blood tests are widely used in modern medicine to diagnose certain illnesses and evaluate the overall health of a patient. To enable testing in resource-limited areas, there has been increasing interest in point-of-care (PoC) testing devices. To process blood samples, liquid mixing with active pumps is usually required, making PoC blood testing expensive and bulky. We explored the possibility of processing approximately 2 μL of whole blood for image flow cytometry using capillary structures that allowed test times of a few minutes without active pumps. Capillary pump structures with five different pillar shapes were simulated using Ansys Fluent to determine which resulted in the fastest whole blood uptake. The simulation results showed a strong influence of the capillary pump pillar shape on the chip filling time. Long and thin structures with a high aspect ratio exhibited faster filling times. Microfluidic chips using the simulated pump design with the most efficient blood uptake were fabricated with polydimethylsiloxane (PDMS) and polyethylene oxide (PEO). The chip filling times were tested with 2 μL of both water and whole blood, resulting in uptake times of 24 s for water and 111 s for blood. The simulated blood plasma results deviated from the experimental filling times by about 35% without accounting for any cell-induced effects. By comparing the flow speed induced by different pump pillar geometries, this study offers insights for the design and optimization of passive microfluidic devices for inhomogenous liquids such as whole blood in sensing applications.

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Capillary-driven microfluidics: impacts of 3D manufacturing on bioanalytical devices

Abstract: The advances in 3D capillary-driven microfluidics for bioanalytical devices, including design and surface chemistry, are presented. Classification of capillary flow control elements is presented based on two functional steps of stop and actuation.

Cited by 10 publications

References 61 publications

Coupling Capillary-Driven Microfluidics with Lateral Flow Immunoassay for Signal Enhancement

Coupling Capillary-Driven Microfluidics with Lateral Flow Immunoassay for Signal Enhancement

Vertical textile epifluidics for integrated real-time electrochemical sweat analysis

Optimization of Microfluidics for Point-of-Care Blood Sensing

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