Polymeric Devices Research Articles

Atmospheric air plasma pre-activation and customizable covalent functionalization of PVDF-membranes of microtiter filter plates

Microtiter-plate-based systems are unified platforms of high-throughput experimentation (HTE). These polymeric devices are used worldwide on a daily basis—mainly in the pharmaceutical industry—for parallel syntheses, reaction optimization, various preclinical studies and high-throughput screening methods. Accordingly, laboratory automation today aims to handle these commercially available multiwell plates, making developments focused on their modifications a priority area of modern applied research. We performed the covalent functionalization of the porous PVDF-membrane of microtiter filter plates as the essence of conventional and common sandwich plate systems by introducing a generalizable method. After surface-activation of the indifferent membrane polymer, customizable functionalization becomes feasible by covalently attached monofunctional molecular linkers. The study was designed with future adaptability, and thus, industrially widespread atmospheric plasma and two different chemical treatments were investigated and compared in terms of practical implementation, polarization effects, extent of labeling, effects on morphology and porosity as well as on permeability. For critical comparison, contact angle measurements, surface ATR-FTIR, 1H-NMR, 19F-NMR, UV–Vis spectroscopy, scanning electron microscopy and permeability tests were used.

Catechol redox maintenance in mussel adhesion.

Catechol-functionalized proteins in mussel holdfasts are essential for underwater adhesion and cohesion and have inspired countless synthetic polymeric materials and devices. However, as catechols are prone to oxidation, long-term performance and stability of these inventions awaits effective antioxidation strategies. In mussels, catechol-mediated interactions are stabilized by 'built-in' homeostatic redox reservoirs that restore catechols oxidized to quinones. Mussel byssus has a typical 'core-shell' architecture in which the core is a degradable fibrous block copolymer consisting of collagen and fibroin coated by robust protein networks stabilized by bis-catecholato-metal and tris-catecholato-metal ion complexes. The coating is well-adapted to protect the core against abrasion, hydrolysis and microbial attack, but it is not impervious to oxidative damage, which, during function, is promptly repaired by redox poise via coacervated catechol-rich and thiol-rich reducing interlayers and inclusions. However, when the e- and H+ equivalents from these reducing reservoirs are depleted, coating damage accumulates, leading to exposure of the vulnerable core to environmental attack. Heeding and translating these strategies is essential for deploying catechols with longer service lifetimes and designing more sustainable next-generation polymeric adhesives.

Theoretical and Experimental Raman Investigation of Mechanical Strain and Electric Field Effects on Conductive Polymers.

Mechanical strain and electric field affect the performance of conductive polymer devices, for which the underlying mechanism should be investigated at the molecular level. This study combines theoretical and experimental Raman approaches to explore the changes in the molecular structure of poly(3-hexylthiophene) (P3HT) and poly(3,4-ethylenedioxythiophene) (PEDOT) under the influence of mechanical strain and external electric fields. Theoretical calculations reveal the pronounced shifts in the main Raman peak if the conjugating length is changed by the mechanical strain, while in experiments, the peak position is unaffected under tensile and bending strain. Under an external electric field, the theoretical results predict a continuous red shift of the main Raman peak accompanied by the change in bond lengths, while in experiments, the same peak exhibits a red shift at an initial increase of the electric field strength and then becomes almost unchanged at a stronger electric field. The discrepancies between calculation and experimental results are attributed to the complex nature of the conjugated chains and noncrystalline domain present in the organic semiconductors, which limits the effectiveness of strain and electric field on the conjugated chains. The results of this study help to bridge the gap between the theoretical study and the actual response of conductive polymers for flexible and electronic device applications.

Multicenter Randomized Controlled Clinical Trial to Compare the Safety and Performance of Two Bone Flap Fixation Systems.

Polymeric clamp-like devices present potential advantages regarding plates and screws to close craniotomies; however, no clinical research has provided enough evidence to compare them. This randomized controlled trial compares the clinical safety and performance of clamp-like devices with the standard of care for craniotomy closure: titanium plates and screws (P&S). A prospective, double-arm, multicenter randomized controlled trial was performed at 3 sites, recruiting 60 patients undergoing neurosurgical interventions requiring craniotomy. Patients were randomly allocated to 2 groups depending on the bone flap fixation system to be used: plates and screws (any brand) and clamp-like devices (Cranial LOOP, NEOS Surgery S.L.). The primary end point of the study (bone flap alignment) was assessed 6 months after surgery through neuroimaging. Secondary end points included adverse events and device deficiency assessment, closure method usability assessed by the surgeon, and patient-reported device-related inconveniences. It was necessary to use a median of 3 Cranial LOOP and 4 plates and 8 screws to close craniotomies. All patients from both groups had equally good bone flap alignment. Most implantations were reported as easy or very easy for both groups, and surgeons were generally satisfied or very satisfied with both treatments. No related adverse events have been reported for any of the treatment groups. Two patients reported discomfort or protuberances caused by P&S; no inconveniences were reported for Cranial LOOP. Cranial LOOP performance is equal to P&S for fixation of the cranial bone flap. In addition, it presents some advantages, such as the use of a lower number of devices, potentially making this system more affordable, and the lack of discomfort previously linked with the use of P&S.

Understanding Oxygen-Induced Reactions and Their Impact on n-Type Polymeric Mixed Conductor-Based Devices.

Electron transporting (n-type) polymeric mixed conductors are an exciting class of materials for devices with aqueous electrolyte interfaces, such as bioelectronic sensors, actuators, and soft charge storage systems. However, their charge transport performance falls short of their p-type counterparts, primarily due to electrochemical side reactions such as the oxygen reduction reaction (ORR). To mitigate ORR, a common strategy in n-type organic semiconductor design focuses on lowering the lowest unoccupied molecular orbital (LUMO) level. Despite empirical observations suggesting a correlation between deep LUMO levels, low ORR, and enhanced electrochemical cycling stability in water, this relationship lacks robust evidence. In this work, we delve into the electrochemical reactions of n-type polymeric mixed conductors with varying LUMO levels and assess the impact of ORR on charge storage performance and organic electrochemical transistor (OECT) operation. Our results reveal a limited correlation between LUMO levels and ORR currents, as well as the electrochemical operational stability of the films. While ORR currents minimally contribute to OECT channel currents under fixed biasing conditions, n-type films self-discharge rapidly at floating potentials in a capacitor-like configuration. The density functional theory analysis, complemented by X-ray photoelectron spectroscopy, underscores the critical role of backbone chemistry in controlling O2-related degradation pathways and device performance losses. These findings highlight the persistent challenge posed by ORR in n-type semiconductor design and advocate for shifting the focus toward exploring chemical moieties with limited O2 interactions to enhance operational stability and performance at n-type film/water interfaces.

Development of photoactive biomaterial using modified fullerene nanoparticles.

Medical device-associated biofilm infections continue to pose a significant challenge for public health. These infections arise from biofilm accumulation on the device, hampering the antimicrobial treatment. In response, significant efforts have been made to design functional polymeric devices that possess antimicrobial properties, limiting or preventing biofilm formation. However, until now none of the strategies showed a promissory effect. Thus, antimicrobial photodynamic therapy (aPDT) has been shown as a promising candidate to overcome this problem. Photosensitizers (PS) are the main key component for aPDT and fullerenes have been chosen as PS due to their good quantum yields and lifetimes spans. In this study, polylactic acid (PLA) surface was modified with fullerene (C60) and reaction was proven by XPS analysis. The biopolymer surface was characterized by AFM, SEM, and water contact angle measurements. The obtained results imply that the highest fullerene precipitation was attained when PLA was modified with ethylenediamine (EDA) before the reaction with C60, as the highest carbon increase was identified using XPS following reaction with C60. While samples' hydrophobicity decreased after PLA modification with EDA, it increased after fullerene precipitation. Which implies that bacteria have a lower propensity to attach. Although the surface of the samples became smoother following PLA modification with EDA and reaction with 0.1% C60 precipitation, with 1% C60 precipitation the surface roughness was comparable to unmodified PLA, according to AFM and SEM analyses. Fullerene-based biopolymers could potentially be used in aPDT to make antimicrobial surfaces or medical devices.

Fully Solution‐Processed Polymeric Multilayer Piezoelectric Devices

AbstractThis study demonstrates fully solution‐processed polymeric multilayer piezoelectric devices. The key challenge, the effective control of the redissolution issue that will cause severe electrical shorting and inconsistent piezoelectric output, is overcome by searching for and using a solvent that offers adequate solubility but extremely slow dissolution for the piezoelectric polymer. The solvent screening methodology is established and demonstrated. The process parameters is systematically optimized to maximize the piezoelectric performance of the multilayer devices. The multilayer devices can output a high charge density of 376 µC m−2, even higher than the record charge density of 250 µC m−2 achieved by traditional contact electrification‐based triboelectric nanogenerators operated in ambient air. The crucial factors for increasing device fabrication yield, namely resistance to short circuits and poling‐induced breakdown, are analyzed. The potential of multilayer devices in practical applications is demonstrated using a five‐layer device as a direct power source and energy harvester. More importantly, the process developed here is transferrable for cost‐effective high‐throughput roll‐to‐roll production. This work thus lays the foundation for the mass production of polymeric multilayer piezoelectric devices and paves the way for their future commercialization.

3D-Printed Polymeric Biomaterials for Health Applications.

3D printing, also known as additive manufacturing, holds immense potential for rapid prototyping and customized production of functional health-related devices. With advancements in polymer chemistry and biomedical engineering, polymeric biomaterials have become integral to 3D-printed biomedical applications. However, there still exists a bottleneck in the compatibility of polymeric biomaterials with different 3D printing methods, as well as intrinsic challenges such as limited printing resolution and rates. Therefore, this review aims to introduce the current state-of-the-art in 3D-printed functional polymeric health-related devices. It begins with an overview of the landscape of 3D printing techniques, followed by an examination of commonly used polymeric biomaterials. Subsequently, examples of 3D-printed biomedical devices are provided and classified into categories such as biosensors, bioactuators, soft robotics, energy storage systems, self-powered devices, and data science in bioplotting. The emphasis is on exploring the current capabilities of 3D printing in manufacturing polymeric biomaterials into desired geometries that facilitate device functionality and studying the reasons for material choice. Finally, an outlook with challenges and possible improvements in the near future is presented, projecting the contribution of general 3D printing and polymeric biomaterials in the field of healthcare.

A personalized, 3D printed, polymeric elastic support device for the prevention of post-MI cardiac remodeling

Abstract Introduction Myocardial remodeling and dilatation following myocardial infarction (MI) initiates a vicious cycle leading to heart failure (HF). The anatomy and pathophysiology of every patient is unique. We have developed a 3D printed, biopolymer based personalized Elastic Support Device, that is 3D printed based on patient’s imaging, aiming to restore cardiac physiology. This study aimed to assess the device on rat MI model. Materials and Methods MI was induced in 24 Sprague Dawley rats by permanently ligating the mid LAD artery via midline sternotomy cut. Twelve animals underwent immediate implantation of the elastic support device that was pre-printed from animal specific 3D echocardiography. The animals were followed up with echocardiography at days -2, 7, 14, 28. The animals were sacrificed at day 28, cardiac tissue and plasma were taken for further histological and biochemical analysis. Results and discussion Mortality was similar at both groups (5 vs 4 in the device and control groups respectively). Ejection fraction reduced in both groups from a baseline of 61.9±8.9% to 47.5±12.7%. Left Ventricular End Diastolic Diameter increased from baseline to day 28 in the control (7.0±0.56mm vs 7.7±1mm) but not the device group (6.87±0.2mm vs 6.93±1.1mm, p<0.05). Parameters of diastolic function such as E/E’ were similar in both groups throughout the follow-up. Mason’s Trichrome stained cardiac sections revealed improved infarct size at the device group (7.4±1.9% vs. 10.6±2.8%) and lower overall cardiac fibrosis. Conclusion In this preliminary small animal model study, the capability to 3D print and implant an imaging based, personalized, 3D printed elastic support device. The cardiac diastolic function was not impaired, and no safety issues were noticed. Furthermore, cardiac dilatation was prevented, and infarct size was reduced.Trial design and results

Cortical, striatal, and thalamic populations self-organize into a functionally connected circuit with long-term memory properties

The human brain is a complex organ with an intricate neuronal connectivity and diverse functional regions. Neurological disorders often disrupt the delicate balance among these anatomical compartments, resulting in severe impairments. The available therapeutic options constitute an incomplete solution as many patients respond partially, highlighting the need for continued research into causes and treatments. Bottom-up approaches, like in vitro models, offer insights into brain functions as they recreate the in vivo microenvironment that allows studying how specific features affect physiological and pathological conditions. In this work, we engineered the cortical-striatal-thalamic (CST) circuit, involved in many brain functions such as action initiation and selection, using a three-compartment polymeric device. We characterized the emerging spontaneous electrophysiological activity by using Micro-Electrode Arrays (MEAs). Cortical neurons exhibited complex bursting activity, which influenced the entire circuit. Striatal and thalamic neurons displayed predominantly tonic firing when isolated, while interconnections with the cortex synchronized and organized their neuronal activity, highlighting the cortical pivotal role in bursting activity and information processing. The CST circuit demonstrated self-organization abilities and displayed high entropy values, indicative of dynamic richness and information encoding potential. Furthermore, we proved the CST’s involvement in learning and memory. Our CST model provides a platform for further exploration into brain circuitry and potential therapeutic interventions, underscoring the necessity of realistic in vitro models to fully understand neurological diseases' pathophysiology.

In-line NIR coupled with machine learning to predict mechanical properties and dissolution profile of PLA-Aspirin

In the production of polymeric drug delivery devices, dissolution profile and mechanical properties of the drug loaded polymeric matrix are considered important Critical Quality Attributes (CQA) for quality assurance. However, currently the industry relies on offline testing methods which are destructive, slow, labour intensive, and costly. In this work, a real-time method for predicting these CQAs in a Hot Melt Extrusion (HME) process is explored using in-line NIR and temperature sensors together with Machine Learning (ML) algorithms. The mechanical and drug dissolution properties were found to vary significantly with changes in processing conditions, highlighting that real-time methods to accurately predict product properties are highly desirable for process monitoring and optimisation. Nonlinear ML methods including Random Forest (RF), K-Nearest Neighbours (KNN) and Recursive Feature Elimination with RF (RFE-RF) outperformed commonly used linear machine learning methods. For the prediction of tensile strength RFE-RF and KNN achieved R2 values 98% and 99%, respectively. For the prediction of drug dissolution, two time points were considered with drug release at t = 6 h as a measure of the extent of burst release, and t = 96 h as a measure of sustained release. KNN and RFE-RF achieved R2 values of 97% and 96%, respectively in predicting the drug release at t = 96 h. This work for the first time reports the prediction of drug dissolution and mechanical properties of drug loaded polymer product from in-line data collected during the HME process.

Flexible electronic-photonic 3D integration from ultrathin polymer chiplets

Integrating flexible electronics and photonics can create revolutionary technologies, but combining these components on a single polymer device has been difficult, particularly for high-volume manufacturing. Here, we present a robust chiplet-level heterogeneous integration of polymer-based circuits (CHIP), where ultrathin polymer electronic and optoelectronic chiplets are vertically bonded at room temperature and shaped into application-specific forms with monolithic Input/Output (I/O). This process was used to develop a flexible 3D integrated optrode with high-density microelectrodes for electrical recording, micro light-emitting diodes (μLEDs) for optogenetic stimulation, temperature sensors for bio-safe operations, and shielding designs to prevent optoelectronic artifacts. CHIP enables simple, high-yield, and scalable 3D integration, double-sided area utilization, and miniaturization of connection I/O. Systematic characterization demonstrated the scheme’s success and also identified frequency-dependent origins of optoelectronic artifacts. We envision CHIP being applied to numerous polymer-based devices for a wide range of applications.

Enhanced capture system for mesenchymal‑type circulating tumor cells using a polymeric microfluidic device 'CTC‑Chip' incorporating cell‑surface vimentin.

CellSearch, the only approved epithelial cell adhesion molecule (EpCAM)‑dependent capture system approved for clinical use, overlooks circulating tumor cells (CTCs) undergoing epithelial‑mesenchymal transition (EMT‑CTCs), which is considered a crucial subtype responsible for metastasis. To address this limitation, a novel polymeric microfluidic device 'CTC‑chip' designed for the easy introduction of any antibody was developed, enabling EpCAM‑independent capture. In this study, antibodies against EpCAM and cell surface vimentin (CSV), identified as cancer‑specific EMT markers, were conjugated onto the chip (EpCAM‑chip and CSV‑chip, respectively), and the capture efficiency was examined using lung cancer (PC9, H441 and A549) and colon cancer (DLD1) cell lines, classified into three types based on EMT markers: Epithelial (PC9), intermediate (H441 and DLD1) and mesenchymal (A549). PC9, H441 and DLD1 cells were effectively captured using the EpCAM‑chip (average capture efficiencies: 99.4, 88.8 and 90.8%, respectively) when spiked into blood. However, A549 cells were scarcely captured (13.4%), indicating that EpCAM‑dependent capture is not suitable for mesenchymal‑type cells. The expression of CSV tended to be higher in cells exhibiting mesenchymal properties and A549 cells were effectively captured with the CSV‑chip (72.4 and 88.4% at concentrations of 10 and 100 µg/ml, respectively) when spiked into PBS. When spiked into blood, the average capture efficiencies were 27.7 and 46.8% at concentrations of 10 and 100 µg/ml, respectively. These results suggest that the CSV‑chip is useful for detecting mesenchymal‑type cells and has potential applications in capturing EMT‑CTCs.

Effect of ethylene oxide and gamma sterilization on surface texture of films and electrospun poly(ε-caprolactone-co-p-dioxanone) (PCLDX) scaffolds

In the field of tissue engineering, synthetic and degradable polyesters like poly(ε-caprolactone) (PCL) and poly(ε-caprolactone-co-p-dioxanone) (PCLDX) are widely used as scaffolds. Our previous research revealed that thermal storage conditions could alter the surface texture of PCL and PCLDX scaffolds, which might influence cell-scaffold interactions in tissue engineering applications. These findings highlighted the importance of multi-scale characterization techniques to identify the scales most sensitive to external changes and the need for personalized surface texture analysis. Sterilization techniques, such as ethylene oxide and gamma radiation, are essential for ensuring the sterility of polymeric medical devices. However, these processes can significantly impact the bulk polymer properties and/or surface texture of the scaffolds, potentially affecting their biocompatibility, safety, and overall performance. Therefore, the influence of sterilization processes on the surface texture of PCLDX films and electrospun nanofibers and to correlate these findings with the thermal and physical properties of the polymer are essential and have been assessed. Our results demonstrated that ethylene oxide maintained the structural integrity and surface texture of PCLDX scaffolds, while gamma irradiation caused a significant reduction in molar mass and increased the number of hills (Shn) and dales (Sdn) on PCLDX samples. Despite these changes, both sterilization methods showed minimal effects on the thermal properties, such as melting temperature and degree of crystallinity, and surface wettability of the scaffolds. This comprehensive surface texture analysis highlights the importance of evaluating feature parameters such as Shn and Sdn for optimizing the performance and biocompatibility of polymeric scaffolds in tissue engineering.

Photoexcitation-Assisted Molecular Doping for High-Performance Polymeric Thermoelectric Materials.

Molecular doping plays a crucial role in modulating the performance of polymeric semiconductor (PSC) materials and devices. Despite the development of numerous molecular dopants and doping methods over the past few decades, achieving highly efficient doping of PSCs remains challenging, primarily because of the inadequate matching of frontier energy levels between the host polymers and the dopants, which is critical for facilitating charge transfer. In this work, we introduce a novel doping method termed photoexcitation-assisted molecular doping (PE-MD), capable of transcending limitations imposed by energy level disparities through the mediation of efficient photoinduced electron transfer between polymers and dopants. This approach significantly amplifies the electrical conductivity of the PDPP4T polymer, increasing it by more than 4 orders of magnitude to a maximum value of 349.67 S cm-1. Given that only the irradiated region experiences a substantial increase in doping level, the PE-MD process facilitates the photoresist-free and precise patterning of doped polymers at a resolution down to 1 μm. Furthermore, the enhanced electrical conductivity of the photoexcitation-assisted molecularly doped PDPP4T film promotes efficient thermoelectric conversion, yielding an impressive initial power factor of 226.1 μW m-1 K-2 and a figure-of-merit (ZT) of 0.18, accompanied by improved thermal and ambient stability. The PE-MD strategy not only remarkably elevates the doping level of PSCs toward efficient thermoelectric conversion but also preserves the easy processability of flexible and integrated devices.

Polydiolcitrate-MoS2 Composite for 3D Printing Radio-Opaque, Bioresorbable Vascular Scaffolds.

Implantable polymeric biodegradable devices, such as biodegradable vascular scaffolds, cannot be fully visualized using standard X-ray-based techniques, compromising their performance due to malposition after deployment. To address this challenge, we describe a new radiopaque and photocurable liquid polymer-ceramic composite (mPDC-MoS2) consisting of methacrylated poly(1,12 dodecamethylene citrate) (mPDC) and molybdenum disulfide (MoS2) nanosheets. The composite was used as an ink with microcontinuous liquid interface production (μCLIP) to fabricate bioresorbable vascular scaffolds (BVS). Prints exhibited excellent crimping and expansion mechanics without strut failures and, importantly, with X-ray visibility in air and muscle tissue. Notably, MoS2 nanosheets displayed physical degradation over time in phosphate-buffered saline solution, suggesting the potential for producing radiopaque, fully bioresorbable devices. mPDC-MoS2 is a promising bioresorbable X-ray-visible composite material suitable for 3D printing medical devices, such as vascular scaffolds, that require noninvasive X-ray-based monitoring techniques for implantation and evaluation. This innovative biomaterial composite system holds significant promise for the development of biocompatible, fluoroscopically visible medical implants, potentially enhancing patient outcomes and reducing medical complications.

Electrospun Polymeric Nanofibers for Malaria Control: Advances in Slow‐Release Mosquito Repellent Technology

AbstractThe textile industry comprises technologies that transform synthetic or natural fibers into yarn, cloth, and felt for manufacturing clothing, upholstery, and household linens. The major public health threat in tropical and subtropical countries is mosquito‐borne malaria. Nowadays, the demand for insect repellent‐based textiles is continuously rising, as they are used for protection against diseases transmitted by mosquitoes. The present work reviews studies on the fabrication of insect repellent containing electrospun polymeric nanofibers as principal tools for protecting people against mosquito bites. Electrospinning technology is a remarkably facile technique for fabricating polymeric nanofiber devices. The technique is outlined and elucidated. The performance of insect repellent‐based polymeric nanofibers against mosquitoes is carefully reported and comprehensively reviewed in‐depth. Furthermore, the progress made on the mathematical modeling of the release rate of repellents through polymeric nanofiber devices is reviewed. The reviewed studies demonstrate that repellents can be released slowly from electrospun nanofibers, increasing the product's protection period against insects. The reviewed works suggest that electrospinning technology has led to an effective and facile methodology for fabricating functional nanofiber textiles with insect repellent. The reviewed studies showed that product‐based repellents can be effective not only against malaria but also against other mosquito‐borne diseases.

Exploring Polymer-Based Additive Manufacturing for Cost-Effective Stamping Devices: A Feasibility Study with Finite Element Analysis.

This research investigates the feasibility of manufacturing stamping devices using Material Extrusion (MEX) Additive Manufacturing (AM) technology, traditionally fabricated from metal, to reduce production costs and time. This study examines polymer-based devices subjected to Finite Element Analysis (FEA) to evaluate their performance in stamping metal sheets of varying thicknesses. The findings reveal that ABS polymer devices, while demonstrating potential, operate near the material's limit under compression forces, particularly for sheet thicknesses up to 1 mm. Specifically, differences of 0.7 mm were observed at the connection radii of 0.25 mm sheets and 1.4 mm for 0.5 mm sheets, with angular deviations of 1.5 degrees for 0.25 mm sheets and 4 degrees for 0.5 mm sheets. Additionally, devices made of Nylon were deemed suitable for reduced-thickness sheets (0.25 mm), performing better than those made of ABS. These results suggest that while ABS devices exhibit significant deviations (up to 45 degrees for 1 mm sheets), the method shows promise for small batch production and prototyping. Further optimisation through material enhancements and mechanical improvements is recommended to minimise deformations and enhance precision.

Improving assay feasibility and biocompatibility of 3D cyclic olefin copolymer microwells by superhydrophilic modification via ultrasonic spray deposition of polyvinyl alcohol

Sample partitioning is a crucial step towards digitization of biological assays on polymer microfluidic platforms. However, effective liquid filling into microwells and long-term hydrophilicity remain a challenge in polymeric microfluidic devices, impeding the applicability in diagnostic and cell culture studies. To overcome this, a method to produce permanent superhydrophilic 3-dimensional microwells using cyclic olefin copolymer (COC) microfluidic chips is presented. The COC substrate is oxidized using UV treatment followed by ultrasonic spray coating of polyvinyl alcohol solution, offering uniform and long-term coating of high-aspect ratio microfeatures. The coated COC surfaces are UV-cured before bonding with a hydrophobic pressure-sensitive adhesive to drive selective filling into the wells. The surface hydrophilicity achieved using this method remains unchanged (water contact angle of 9°) for up to 6 months and the modified surface is characterized for physical (contact angle & surface energy, morphology, integrity of microfeatures and roughness), chemical composition (FTIR, Raman spectroscopy) and coating stability (pH, temperature, time). To establish the feasibility of the modified surface in biological applications, PVA-coated COC microfluidic chips are tested for DNA sensing (digital LAMP detection of CMV), and biocompatibility through protein adsorption and cell culture studies (cell adhesion, viability, and metabolic activity). Kidney and breast cells remained viable for the duration of testing (7 days) on this modified surface, and the coating did not affect the protein content, morphology or quality of the cultured cells. The ultrasonic spray coated system, coating with 0.25 % PVA for 15 cycles with 0.12 A current after UV oxidation, increased the surface energy of the COC (naturally hydrophobic) from 22.04 to 112.89 mJ/m2 and improved the filling efficiency from 40 % (native untreated COC) to 94 % in the microwells without interfering with the biocompatibility of the surface, proving to be an efficient, high-throughput and scalable method of microfluidic surface treatment for diagnostic and cell growth applications.

Dynamic fabrication of porous polymeric coating for efficient passive daytime radiative cooling using in-situ pore-formation strategy

Porous polymeric material has emerged as promising choice for making passive daytime radiative cooling (PDRC) emitter. However, it is still an unmet challenge to establish a flexible method to achieve dynamic pore-formation for the purpose of studying the relationships between the porous structure and the resultant cooling performance. The current study reports a novel strategy to construct asymmetric multi-layered porous structure in situ within the matrix of pre-formed polystyrene coating. The modified procedure of inverse emulsion - breath figure method is adopted, and solvent-nonsolvent exchanging process is also involved during the pore-formation process, leading to the formation of hierarchical porous structure with rather high porosity. Geometrical features of the generated pores are effectively regulated by simple adjustment of the experimental parameters of the water ratio of the emulsion and the humidity. The relationship between the pore structure and optical & cooling properties has been established based on experimental facts. By tuning of optimal conditions, the in-situ pore-formation can endow the polymeric coating with high solar reflectance (∼85 %) and infrared emittance (∼98.4 %), resulting in passive temperature drop of 12 °C and cooling power of 91 W/m2. This study provides experimental information to get some insight into the designing principle of porous polymeric PDRC materials, and formulates unique strategy of in-situ functionalization via structural transformation upon polymeric objects or devices.