Perspectives in translating microfluidic devices from laboratory prototyping into scale-up production

Recent advances in nanomaterial-based optical biosensors for food safety applications: Ochratoxin-A detection, as case study

Global population growth tremendously impacts the global food industry, endangering food safety and quality. Mycotoxins, particularly Ochratoxin-A (OTA), emerge as a food chain production threat, since it is produced by fungus that contaminates different food species and products. Beyond this, OTA exhibits a possible human toxicological risk that can lead to carcinogenic and neurological diseases. A selective, sensitive, and reliable OTA biodetection approach is essential to ensure food safety. Current detection approaches rely on accurate and time-consuming laboratory techniques performed at the end of the food production process, or lateral-flow technologies that are rapid and on-site, but do not provide quantitative and precise OTA concentration measurements. Nanoengineered optical biosensors arise as an avant-garde solution, providing high sensing performance, and a fast and accurate OTA biodetection screening, which is attractive for the industrial market. This review core presents and discusses the recent advancements in optical OTA biosensing, considering engineered nanomaterials, optical transduction principle and biorecognition methodologies. Finally, the major challenges and future trends are discussed, and current patented OTA optical biosensors are emphasized for a particular promising detection method.

Biomimetic Materials for Skin Tissue Regeneration and Electronic Skin

Biomimetic materials have become a promising alternative in the field of tissue engineering and regenerative medicine to address critical challenges in wound healing and skin regeneration. Skin-mimetic materials have enormous potential to improve wound healing outcomes and enable innovative diagnostic and sensor applications. Human skin, with its complex structure and diverse functions, serves as an excellent model for designing biomaterials. Creating effective wound coverings requires mimicking the unique extracellular matrix composition, mechanical properties, and biochemical cues. Additionally, integrating electronic functionality into these materials presents exciting possibilities for real-time monitoring, diagnostics, and personalized healthcare. This review examines biomimetic skin materials and their role in regenerative wound healing, as well as their integration with electronic skin technologies. It discusses recent advances, challenges, and future directions in this rapidly evolving field.

Droplet Microfluidic Devices: Working Principles, Fabrication Methods, and Scale-Up Applications

Compared with the conventional emulsification method, droplets generated within microfluidic devices exhibit distinct advantages such as precise control of fluids, exceptional monodispersity, uniform morphology, flexible manipulation, and narrow size distribution. These inherent benefits, including intrinsic safety, excellent heat and mass transfer capabilities, and large surface-to-volume ratio, have led to the widespread applications of droplet-based microfluidics across diverse fields, encompassing chemical engineering, particle synthesis, biological detection, diagnostics, emulsion preparation, and pharmaceuticals. However, despite its promising potential for versatile applications, the practical utilization of this technology in commercial and industrial is extremely limited to the inherently low production rates achievable within a single microchannel. Over the past two decades, droplet-based microfluidics has evolved significantly, considerably transitioning from a proof-of-concept stage to industrialization. And now there is a growing trend towards translating academic research into commercial and industrial applications, primarily driven by the burgeoning demands of various fields. This paper comprehensively reviews recent advancements in droplet-based microfluidics, covering the fundamental working principles and the critical aspect of scale-up integration from working principles to scale-up integration. Based on the existing scale-up strategies, the paper also outlines the future research directions, identifies the potential opportunities, and addresses the typical unsolved challenges.

Tunable In Situ Synthesis of Ultrathin Extracellular Matrix-Derived Membranes in Organ-on-a-Chip Devices

Thin cell culture membranes in organ-on-a-chip (OOC) devices are used to model a wide range of thin tissues. While early and most current platforms use microporous or fibrous elastomeric or thermoplastic membranes, there is an emerging class of devices using extra-cellular matrix (ECM) protein-based membranes to improve their biological relevance. These ECM-based membranes present physiologically relevant properties, but they are difficult to integrate into OOC devices due to their relative fragility. Additionally, the specialized fabrication methods developed to date make comparison between methods difficult. This work presents the development and characterization of a method to produce ultrathin matrix-derived membranes (UMM) in OOC devices that requires only a preassembled thermoplastic device and a micropipette, decoupling the device and UMM fabrication processes. Control over the thickness and permeability of the UMM is demonstrated, along with integration of the UMM in a device enabling high-resolution on-chip microscopy. The reliability of the UMM fabrication method is leveraged to develop a medium-throughput well-plate format device with 32 independent UMM-integrated samples. Finally, proof-of-concept cell culture experiments are demonstrated. Due to its simplicity and controllability, the presented method has the potential to overcome technical barriers preventing wider adoption of physiologically relevant ECM-based membranes in OOC devices.

Recent developments in the fabrication of food microparticles and nanoparticles using microfluidic systems

Microfluidics is revolutionizing the production of microparticles and nanoparticles, offering precise control over dimensions and internal structure. This technology facilitates the creation of colloidal delivery systems capable of encapsulating and releasing nutraceuticals. Nutraceuticals, often derived from food-grade ingredients, can be used for developing functional foods. This review focuses on the principles and applications of microfluidic systems in crafting colloidal delivery systems for nutraceuticals. It explores the foundational principles behind the development of microfluidic devices for nutraceutical encapsulation and delivery. Additionally, it examines the prospects and challenges with using microfluidics for functional food development. Microfluidic systems can be employed to form emulsions, liposomes, microgels and microspheres, by manipulating minute volumes of fluids flowing within microchannels. This versatility can enhance the dispersibility, stability, and bioavailability of nutraceuticals. However, challenges as scaling up production, fabrication complexity, and microchannel clogging hinder the widespread application of microfluidic technologies. In conclusion, this review highlights the potential role of microfluidics in design and fabrication of nutraceutical delivery systems. At present, this technology is most suitable for exploring the role of specific delivery system features (such as particle size, composition and morphology) on the stability and bioavailability of nutraceuticals, rather than for large-scale production of nutraceutical delivery systems.

Towards Industrially Important Applications of Enhanced Organic Reactions by Microfluidic Systems

This review presents a comprehensive evaluation for the manufacture of organic molecules via efficient microfluidic synthesis. Microfluidic systems provide considerably higher control over the growth, nucleation, and reaction conditions compared with traditional large-scale synthetic methods. Microfluidic synthesis has become a crucial technique for the quick, affordable, and efficient manufacture of organic and organometallic compounds with complicated characteristics and functions. Therefore, a unique, straightforward flow synthetic methodology can be developed to conduct organic syntheses and improve their efficiency.

A comprehensive overview of advanced dynamic in vitro intestinal and hepatic cell culture models

Orally administered drugs pass through the gastrointestinal tract before being absorbed in the small intestine and metabolised in the liver. To test the efficacy and toxicity of drugs, animal models are often employed; however, they are not suitable for investigating drug-tissue interactions and making reliable predictions, since the human organism differs drastically from animals in terms of absorption, distribution, metabolism and excretion of substances. Likewise, simple static in vitro cell culture systems currently used in preclinical drug screening often do not resemble the native characteristics of biological barriers. Dynamic models, on the other hand, provide in vivo-like cell phenotypes and functionalities that offer great potential for safety and efficacy prediction. Herein, current microfluidic in vitro intestinal and hepatic models are reviewed, namely single- and multi-tissue micro-bioreactors, which are associated with different methods of cell cultivation, i.e., scaffold-based versus scaffold-free.

Microfluidic based continuous enzyme immobilization: A comprehensive review

Conventional techniques for enzyme immobilization suffer from suboptimal activity recovery due to insufficient enzyme loading and inadequate stability. Furthermore, these techniques are time-consuming and involve multiple steps which limit the applicability of immobilized enzymes. In contrast, the use of microfluidic devices for enzyme immobilization has garnered significant attention due to its ability to precisely control immobilization parameters, resulting in highly active immobilized enzymes. This approach offers several advantages, including reduced time and energy consumption, enhanced mass-heat transfer, and improved control over the mixing process. It maintains the superior structural configuration in immobilized form which ultimately affects the overall efficiency. The present review article comprehensively explains the design, construction, and various methods employed for enzyme immobilization using microfluidic devices. The immobilized enzymes prepared using these techniques demonstrated excellent catalytic activity, remarkable stability, and outstanding recyclability. Moreover, they have found applications in diverse areas such as biosensors, biotransformation, and bioremediation. The review article also discusses potential future developments and foresees significant challenges associated with enzyme immobilization using microfluidics, along with potential remedies. The development of this advanced technology not only paves the way for novel and innovative approaches to enzyme immobilization but also allows for the straightforward scalability of microfluidic-based techniques from an industrial standpoint.

Next-Generation Microfluidics for Biomedical Research and Healthcare Applications

Microfluidic systems offer versatile biomedical tools and methods to enhance human convenience and health. Advances in these systems enables next-generation microfluidics that integrates automation, manipulation, and smart readout systems, as well as design and three-dimensional (3D) printing for precise production of microchannels and other microstructures rapidly and with great flexibility. These 3D-printed microfluidic platforms not only control the complex fluid behavior for various biomedical applications, but also serve as microconduits for building 3D tissue constructs-an integral component of advanced drug development, toxicity assessment, and accurate disease modeling. Furthermore, the integration of other emerging technologies, such as advanced microscopy and robotics, enables the spatiotemporal manipulation and high-throughput screening of cell physiology within precisely controlled microenvironments. Notably, the portability and high precision automation capabilities in these integrated systems facilitate rapid experimentation and data acquisition to help deepen our understanding of complex biological systems and their behaviors. While certain challenges, including material compatibility, scaling, and standardization still exist, the integration with artificial intelligence, the Internet of Things, smart materials, and miniaturization holds tremendous promise in reshaping traditional microfluidic approaches. This transformative potential, when integrated with advanced technologies, has the potential to revolutionize biomedical research and healthcare applications, ultimately benefiting human health. This review highlights the advances in the field and emphasizes the critical role of the next generation microfluidic systems in advancing biomedical research, point-of-care diagnostics, and healthcare systems.

Direct isolation of small extracellular vesicles from human blood using viscoelastic microfluidics

Small extracellular vesicles (sEVs; <200 nm) that contain lipids, nucleic acids, and proteins are considered promising biomarkers for a wide variety of diseases. Conventional methods for sEV isolation from blood are incompatible with routine clinical workflows, significantly hampering the utilization of blood-derived sEVs in clinical settings. Here, we present a simple, viscoelastic-based microfluidic platform for label-free isolation of sEVs from human blood. The separation performance of the device is assessed by isolating fluorescent sEVs from whole blood, demonstrating purities and recovery rates of over 97 and 87%, respectively. Significantly, our viscoelastic-based microfluidic method also provides for a remarkable increase in sEV yield compared to gold-standard ultracentrifugation, with proteomic profiles of blood-derived sEVs purified by both methods showing similar protein compositions. To demonstrate the clinical utility of the approach, we isolate sEVs from blood samples of 20 patients with cancer and 20 healthy donors, demonstrating that elevated sEV concentrations can be observed in blood derived from patients with cancer.

Rapid integration of screen-printed electrodes into thermoplastic organ-on-a-chip devices for real-time monitoring of trans-endothelial electrical resistance

Trans-endothelial electrical resistance (TEER) is one of the most widely used indicators to quantify the barrier integrity of endothelial layers. Over the last decade, the integration of TEER sensors into organ-on-a-chip (OOC) platforms has gained increasing interest for its efficient and effective measurement of TEER in OOCs. To date, microfabricated electrodes or direct insertion of wires has been used to integrate TEER sensors into OOCs, with each method having advantages and disadvantages. In this study, we developed a TEER-SPE chip consisting of carbon-based screen-printed electrodes (SPEs) embedded in a poly(methyl methacrylate) (PMMA)-based multi-layered microfluidic device with a porous poly(ethylene terephthalate) membrane in-between. As proof of concept, we demonstrated the successful cultures of hCMEC/D3 cells and the formation of confluent monolayers in the TEER-SPE chip and obtained TEER measurements for 4 days. Additionally, the TEER-SPE chip could detect changes in the barrier integrity due to shear stress or an inflammatory cytokine (i.e., tumor necrosis factor-α). The novel approach enables a low-cost and facile fabrication of carbon-based SPEs on PMMA substrates and the subsequent assembly of PMMA layers for rapid prototyping. Being cost-effective and cleanroom-free, our method lowers the existing logistical and technical barriers presenting itself as another step forward to the broader adoption of OOCs with TEER measurement capability.

Miniaturized Non-Contact Heating and Transmitted Light Imaging Using an Inexpensive and Modular 3D-Printed Platform for Molecular Diagnostics

The ability to simultaneously heat and image samples using transmitted light is crucial for several biological applications. However, existing techniques such as heated stage microscopes, thermal cyclers equipped with imaging capabilities, or non-contact heating systems are often bulky, expensive, and complex. This work presents the development and characterization of a Miniaturized Optically-clear Thermal Enclosure (MOTE) system-an open-source, inexpensive, and low-powered modular system-capable of convectively heating samples while simultaneously imaging them with transmitted light. We develop and validate a computational fluid dynamics (CFD) model to design and optimize the heating chamber. The model simulates velocity and temperature profiles within the heating chamber for various chamber materials and sizes. The computational model yielded an optimal chamber dimension capable of achieving a stable temperature ranging from ambient to 95 °C with a spatial discrepancy of less than 1.5 °C, utilizing less than 8.5 W of power. The dual-functionality of the MOTE system, enabling synchronous heating and transmitted light imaging, was demonstrated through the successful execution of paper-based LAMP reactions to detect λ DNA samples in real-time down to 10 copies/µL of the target concentration. The MOTE system offers a promising and flexible platform for various applications, from molecular diagnostics to biochemical analyses, cell biology, genomics, and education.

Throughput-scalable manufacturing of SARS-CoV-2 mRNA lipid nanoparticle vaccines

Lipid nanoparticles (LNPs) are a potent delivery technology that have made it possible for the recent clinical breakthroughs in mRNA therapeutics and vaccines. A key challenge to the broader implementation of mRNA therapeutics and vaccines is the development of technology to produce precisely defined LNP formulations, with throughput that can scale from discovery to commercial manufacturing and meet the stringent manufacturing standards of the pharmaceutical industry. To address these challenges, we have developed a microfluidic chip that incorporates 1×, 10×, or 256× LNP-generating units that achieve scalable production rates of up to 17 L/h of precisely defined LNPs. Using these chips, we demonstrate that LNP physical properties and potency in vivo are unchanged as throughput is scaled. Our chips are fabricated out of silicon and glass substrates, which have excellent solvent compatibility, compatibility with pharmaceutical manufacturing, and can be fully reset and reused. SARS-CoV-2 mRNA-LNP vaccines formulated by our chips triggered potent antibody responses in a preclinical study. These results demonstrate the feasibility of directly translating microfluidic-generated LNPs to the scale necessary for commercial production.

UV-Assisted Hyperbranched Poly(β-amino ester) Modification of a Silica Membrane for Two-Step Microfluidic DNA Extraction from Blood

Integrating nucleic acid extraction in amplification-based point-of-care diagnostics will be a significant feature for next-generation point-of-care virus detection devices. However, extracting DNA efficiently on a microfluidic chip poses many technological and commercialization challenges, including manual steps, multiple instruments, pretreatment processes, and the use of organic solvents (ethanol, IPA) that inhibit detection, which is not viable with routine testing such as viral load monitoring of transplant patients for post-operative care. This paper presents a microfluidic system capable of two-step DNA extraction from blood using a UV-assisted hyperbranched poly(β-amino ester) (HPAE)-modified silica membrane for cytomegalovirus (CMV) detection in a rapid and instrument-free manner without the presence of amplification inhibitors. HPAEs of varying branch ratios were synthesized, screened, and coated on a silica membrane and bonded between two layers of poly(methyl methacrylate) (PMMA) substrates. Our system could selectively extract DNA from blood with an efficiency of 94% and a lower limit viral load of 300 IU/mL in 20 min. The extracted DNA was used as the template for real-time loop-mediated isothermal amplification (LAMP)-based detection of CMV and was found to produce a fluorescent signal intensity that was comparable with commercially extracted templates. This system can be integrated easily with a nucleic acid amplification system and used for routine rapid testing of viral load in patient blood samples.

Microreactor-based micro/nanomaterials: fabrication, advances, and outlook

Micro/nanomaterials are widely used in optoelectronics, environmental materials, bioimaging, agricultural industries, and drug delivery owing to their marvelous features, such as quantum tunneling, size, surface and boundary, and Coulomb blockade effects. Recently, microreactor technology has opened up broad prospects for green and sustainable chemical synthesis as a powerful tool for process intensification and microscale manipulation. This review focuses on recent progress in the microreactor synthesis of micro/nanomaterials. First, the fabrication and design principles of existing microreactors for producing micro/nanomaterials are summarized and classified. Afterwards, typical examples are shown to demonstrate the fabrication of micro/nanomaterials, including metal nanoparticles, inorganic nonmetallic nanoparticles, organic nanoparticles, Janus particles, and MOFs. Finally, the future research prospects and key issues of microreactor-based micro/nanomaterials are discussed. In short, microreactors provide new ideas and methods for the synthesis of micro/nanomaterials, which have huge potential and inestimable possibilities in large-scale production and scientific research.

A Method for Rapid, Quantitative Evaluation of Particle Sorting in Microfluidics Using Basic Cytometry Equipment

This paper describes, in detail, a method that uses flow cytometry to quantitatively characterise the performance of continuous-flow microfluidic devices designed to separate particles. Whilst simple, this approach overcomes many of the issues with the current commonly utilised methods (high-speed fluorescent imaging, or cell counting via either a hemocytometer or a cell counter), as it can accurately assess device performance even in complex, high concentration mixtures in a way that was previously not possible. Uniquely, this approach takes advantage of pulse processing in flow cytometry to allow quantitation of cell separation efficiencies and resulting sample purities on both single cells as well as cell clusters (such as circulating tumour cell (CTC) clusters). Furthermore, it can readily be combined with cell surface phenotyping to measure separation efficiencies and purities in complex cell mixtures. This method will facilitate the rapid development of a raft of continuous flow microfluidic devices, will be helpful in testing novel separation devices for biologically relevant clusters of cells such as CTC clusters, and will provide a quantitative assessment of device performance in complex samples, which was previously impossible.

Robust Full-Spectral Color Tuning of Photonic Colloids

Creation of color through photonic morphologies manufactured by molecular self-assembly is a promising approach, but the complexity and lack of robustness of the fabrication processes have limited their technical exploitation. Here, it is shown that photonic spheres with full-color tuning across the entire visible spectrum can be readily and reliably achieved by the emulsification of solutions containing a block copolymer (BCP) and two swelling additives. Solvent diffusion out of the emulsion droplets gives rise to 20-150 µm-sized spheres with an onion-like lamellar morphology. Controlling the lamellar thickness by differential swelling with the two additives enables color tuning of the Bragg interference-based reflection band across the entire visible spectrum. By studying five different systems, a set of important principles for manufacturing photonic colloids is established. Two swelling additives are required, one of which must exhibit strong interactions with one of the BCP blocks. The additives should be chosen to enhance the dielectric contrast, and the formation kinetics of the spheres must be sufficiently slow to enable the emergence of the photonic morphology. The proposed approach is versatile and robust and allows the scalable production of photonic pigments with possible future applications in inks for cosmetics and arts, coatings, and displays.

Microfluidic SERS devices: brightening the future of bioanalysis

A new avenue has opened up for applications of surface-enhanced Raman spectroscopy (SERS) in the biomedical field, mainly due to the striking advantages offered by SERS tags. SERS tags provide indirect identification of analytes with rich and highly specific spectral fingerprint information, high sensitivity, and outstanding multiplexing potential, making them very useful in in vitro and in vivo assays. The recent and innovative advances in nanomaterial science, novel Raman reporters, and emerging bioconjugation protocols have helped develop ultra-bright SERS tags as powerful tools for multiplex SERS-based detection and diagnosis applications. Nevertheless, to translate SERS platforms to real-world problems, some challenges, especially for clinical applications, must be addressed. This review presents the current understanding of the factors influencing the quality of SERS tags and the strategies commonly employed to improve not only spectral quality but the specificity and reproducibility of the interaction of the analyte with the target ligand. It further explores some of the most common approaches which have emerged for coupling SERS with microfluidic technologies, for biomedical applications. The importance of understanding microfluidic production and characterisation to yield excellent device quality while ensuring high throughput production are emphasised and explored, after which, the challenges and approaches developed to fulfil the potential that SERS-based microfluidics have to offer are described.

Labeling on a Chip of Cellular Fibronectin and Matrix Metallopeptidase-9 in Human Serum

We present a microfluidic chip for protein labeling in the human serum-based matrix. Serum is a complex sample matrix that contains a variety of proteins, and a matrix is used in many clinical tests. In this study, the device performance was tested using commercial serum samples from healthy donors spiked with the following target proteins: cellular fibronectin (c-Fn) and matrix metallopeptidase 9 (MMP9). The microfluidic molds were fabricated using micro milling on acrylic and using stereolithography (SLA) three-dimensional (3D) printing for an alternative method and comparison. A simple quality control was performed for both fabrication mold methods to inspect the channel height of the chip that plays a critical role in the labeling process. The fabricated microfluidic chip shows a good reproducibility and repeatability of the performance for the optimized channel height of 150 µm. The spiked proteins of c-Fn and MMP9 in the human serum-based matrix, were successfully labeled by the functionalized magnetic nanoparticles (MNPs). The biomarker labeling occurring in the serum was compared using a simple matrix sample: phosphate buffer. The measured signals obtained by using a magnetoresistive (MR) biochip platform showed that the labeling using the proposed microfluidic chip is in good agreement for both matrixes, i.e., the analytical performance (sensitivity) obtained with the serum, near the relevant cutoff values, is within the uncertainty of the measurements obtained with a simple and more controlled matrix: phosphate buffer. This finding is promising for stroke patient stratification where these biomarkers are found at high concentrations in the serum.

Advances in Concentration Gradient Generation Approaches in a Microfluidic Device for Toxicity Analysis

This systematic review aimed to analyze the development and functionality of microfluidic concentration gradient generators (CGGs) for toxicological evaluation of different biological organisms. We searched articles using the keywords: concentration gradient generator, toxicity, and microfluidic device. Only 33 of the 352 articles found were included and examined regarding the fabrication of the microdevices, the characteristics of the CGG, the biological model, and the desired results. The main fabrication method was soft lithography, using polydimethylsiloxane (PDMS) material (91%) and SU-8 as the mold (58.3%). New technologies were applied to minimize shear and bubble problems, reduce costs, and accelerate prototyping. The Christmas tree CGG design and its variations were the most reported in the studies, as well as the convective method of generation (61%). Biological models included bacteria and nematodes for antibiotic screening, microalgae for pollutant toxicity, tumor and normal cells for, primarily, chemotherapy screening, and Zebrafish embryos for drug and metal developmental toxicity. The toxic effects of each concentration generated were evaluated mostly with imaging and microscopy techniques. This study showed an advantage of CGGs over other techniques and their applicability for several biological models. Even with soft lithography, PDMS, and Christmas tree being more popular in their respective categories, current studies aim to apply new technologies and intricate architectures to improve testing effectiveness and reduce common microfluidics problems, allowing for high applicability of toxicity tests in different medical and environmental models.

A Review of Microinjection Moulding of Polymeric Micro Devices

Polymeric micro devices are gaining huge market potential in broad areas of medical devices, diagnostic devices, drug delivery, and optical applications. Current research is focusing on developing functional polymeric micro devices on a mass-production scale. Microinjection moulding is a promising technique suitable for fabricating polymeric micro devices. This review aims to summarise the primary achievements that have been achieved in various aspects of microinjection moulding of polymer micro devices, consisting of micro parts and micro surface structures. The relationships of the machine, process, rheology, tooling, micro/nanoscale replication, morphology, properties, and typical applications are reviewed in detail. Finally, a conclusion and challenges are highlighted.

Versatile and Low-Cost Fabrication of Modular Lock-and-Key Microfluidics for Integrated Connector Mixer Using a Stereolithography 3D Printing

We present a low-cost and simple method to fabricate a novel lock-and-key mixer microfluidics using an economic stereolithography (SLA) three-dimensional (3D) printer, which costs less than USD 400 for the investment. The proposed study is promising for a high throughput fabrication module, typically limited by conventional microfluidics fabrications, such as photolithography and polymer-casting methods. We demonstrate the novel modular lock-and-key mixer for the connector and its chamber modules with optimized parameters, such as exposure condition and printing orientation. In addition, the optimization of post-processing was performed to investigate the reliability of the fabricated hollow structures, which are fundamental to creating a fluidic channel or chamber. We found out that by using an inexpensive 3D printer, the fabricated resolution can be pushed down to 850 µm and 550 µm size for squared- and circled-shapes, respectively, by the gradual hollow structure, applying vertical printing orientation. These strategies opened up the possibility of developing straightforward microfluidics platforms that could replace conventional microfluidics mold fabrication methods, such as photolithography and milling, which are costly and time consuming. Considerably cheap commercial resin and its tiny volume employed for a single printing procedure significantly cut down the estimated fabrication cost to less than 50 cents USD/module. The simulation study unravels the prominent properties of the fabricated devices for biological fluid mixers, such as PBS, urine and plasma blood. This study is eminently prospective toward microfluidics application in clinical biosensing, where disposable, low-cost, high-throughput, and reproducible chips are highly required.

Investigation of Solvent-Assisted In-Mold Bonding of Cyclic Olefin Copolymer (COC) Microfluidic Chips

The bonding of microfluidic chips is an essential process to enclose microchannels or microchambers in a lab-on-a-chip. In order to improve the bonding quality while reducing the fabrication time, a solvent-assisted bonding strategy was proposed to seal the microchannels immediately after the cover sheet and substrate chip was injection molded in a single mold. Proper organic solvents were selected and the influences of solvent ratios on the surface roughness, microchannel morphology, and contact angle of microfluidic chips were investigated. When the solvent bonding was integrated in the mold, the influences of solvent volume fraction, solvent dosage, bonding pressure, and bonding time on the bonding quality were analyzed. Results show that the solvent cyclohexane needs to be mixed with isopropanol to reduce the dissolution effect. Solvent treatment is suggested to be performed on the cover sheet with a cyclohexane volume fraction of 70% and a dose of 1.5 mL, a bonding pressure of 2 MPa, and a bonding time of 240 s. The bonding strength reaches 913 kPa with the optimized parameters, while the microchannel deformation was controlled below 8%.