Plastic materials do not generally form irreversible bonds with poly(dimethylsiloxane) (PDMS) regardless of oxygen plasma treatment and a subsequent thermal process. In this paper, we perform plastic-PDMS bonding at room temperature, mediated by the formation of a chemically robust amine-epoxy bond at the interfaces. Various plastic materials, such as poly(methylmethacrylate) (PMMA), polycarbonate (PC), polyimide (PI), and poly(ethylene terephthalate) (PET) were adopted as choices for plastic materials. Irrespective of the plastic materials used, the surfaces were successfully modified with amine and epoxy functionalities, confirmed by the surface characterizations such as water contact angle measurements and X-ray photoelectron spectroscopy (XPS), and chemically robust and irreversible bonding was successfully achieved within 1 h at room temperature. The bonding strengths of PDMS with PMMA and PC sheets were measured to be 180 and 178 kPa, respectively, and their assemblies containing microchannel structures endured up to 74 and 84 psi (510 and 579 kPa) of introduced compressed air, respectively, without destroying the microdevices, representing a robust and highly stable interfacial bonding. In addition to microchannel-molded PDMS bonded with flat plastic substrates, microchannel-embossed plastics were also bonded with a flat PDMS sheet, and both types of bonded assemblies displayed sufficiently robust bonding, tolerating an intense influx of liquid whose per-minute injection volume was nearly 1000 to 2000 times higher than the total internal volume of the microchannel used. In addition to observing the bonding performance, we also investigated the potential of surface amine and epoxy functionalities as durable chemical adhesives by observing their storage-time-dependent bonding performances.
A novel device architecture for preparing a transparent and low-voltage graphene pressure-sensor matrix on plastic and rubber substrates is demonstrated. The coplanar gate configuration of the graphene transistor enables a simplified procedure. The resulting devices exhibit excellent device performance, including a high transparency of ca. 80% in the visible range, a low operating voltage less than 2 V, a high pressure sensitivity of 0.12 kPa(-1) , and excellent mechanical durability over 2500 cycles.
Given the enormous increase in the risks of bone and cartilage defects with the rise in the aging population, the current treatments available are insufficient for handling this burden, and the supply of donor organs for transplantation is limited. Therefore, tissue engineering is a promising approach for treating such defects. Advances in materials research and high-tech optimized fabrication of scaffolds have increased the efficiency of tissue engineering. Electrospun nanofibrous scaffolds and hydrogel scaffolds mimic the native extracellular matrix of bone, providing a support for bone and cartilage tissue engineering by increasing cell viability, adhesion, propagation, and homing, and osteogenic isolation and differentiation, vascularization, host integration, and load bearing. The use of these scaffolds with advanced three- and four-dimensional printing technologies has enabled customized bone grafting. In this review, we discuss the different approaches used for cartilage and bone tissue engineering.
A new strategy is needed for the mass production of microand nanostructures on a wide variety of substrates, which can be applied in various fields of manufacturing, for example, microelectronics, micro-optics, photonics, and chemical or biosensors. Since the early 1990s, simple unconventional lithographic techniques, such as soft lithography, [1][2][3] imprint lithography, [4,5] and others, [6][7][8][9][10][11] have been developed for the economical and rapid fabrication of micro-and nanostructures applicable to various fields of electronics and optics. However, as the feature size diminishes rapidly, a grand challenge that remains to be overcome is the fabrication of dense and complex nanostructures with high aspect ratios, and, in this process, accomplishing the complete release of the mold from the patterned substrate becomes essential. For this reason, many research efforts are directed towards lowering the adhesion between the mold and the patterned polymer on a substrate.Here, we introduce a new strategy to achieve an antiadhesion surface for the simple, rapid fabrication and replication of nanostructures with high fidelity that is applicable to all types of stamping molds. In this study, the surface of various hard and soft molds was bound strongly and covalently with low-viscosity poly(dimethylsiloxane) (PDMS), which has good surface properties for the molding process, i.e., low surface energy and low adhesion properties, like normal PDMS molds. The surface modification was accomplished irrespective of the basic materials comprising the mold. In particular, to show the antiadhesion effect of the coated PDMS layer, molds with nanoscale features were replicated from SiO 2 nanostructures using general UV-curable polymers, such as optical adhesives and photoresists originally designed to have good adhesion with SiO 2 . With this method, we replicated complex nanostructures with high aspect ratios, for example, 80 nm line patterns at least 400 nm in height and 150 nm line patterns that were 1.4 lm in height, on various substrates such as glass, Si/SiO 2 wafers, and flexible polymer sheets with areas exceeding several tens of square centimeters.In general, soft lithography has adopted PDMS as the mold material because of its high elasticity, easy replicability, and intrinsically low adhesion properties. However, because of the innate softness of PDMS [1] it is not suitable for molding nanoscale features, and numerous molds with high mechanical strength have been introduced as an alternative to improve the fidelity in nanostructure molding. [8][9][10][11][12][13] The bases for these molds are typically urethanes, [14,15] epoxies, and perfluoro polymers. [13,16,17] They are optically transparent and easily replicable upon UV polymerization. However, urethanes and epoxies possess high surface energies, requiring antiadhesion treatment of the surface for easy release of the mold. To overcome this problem, a new mold that contains a perfluoroether polymer [13,16,17] as a basic component was developed to reduce the ...
Here we propose a new scheme for bonding poly(dimethylsiloxane) (PDMS), namely, a "chemical gluing", at room temperature by anchoring chemical functionalities on the surfaces of PDMS. Aminosilane and epoxysilane are anchored separately on the surfaces of two PDMS substrates, the reaction of which are well-known to form a strong amine-epoxy bond, therefore acting as a chemical glue. The bonding is performed for 1 h at room temperature without employing heat. We characterize the surface properties and composition by contact angle measurement, X-ray photoelectron spectroscopy analysis, and fluorescence measurement to confirm the formation of surface functionalities and investigate the adhesion strength by means of pulling, tearing, and leakage tests. As confirmed by the above-mentioned analyses and tests, PDMS surfaces were successfully modified with amine and epoxy functionalities, and a bonding based on the amine-epoxy chemical gluing was successfully realized within 1 h at room temperature. The bonding was sufficiently robust to tolerate intense introduction of liquid whose per minute injection volume was almost 2000 times larger than the total internal volume of the microchannel used. In addition to the bonding of PDMS-PDMS homogeneous assembly, the bonding of the PDMS-poly(ethylene terephthalate) heterogeneous assembly was also examined. We also investigate the potential use of the multifunctionalized walls inside the microchannel, generated as a consequence of the chemical gluing, as a platform for the targeted immobilization.
This paper introduces an instantaneous and robust strategy for bonding a variety of non-silicon substrates such as thermoplastics, metals, an alloy, and ceramics to poly(dimethylsiloxane) (PDMS) irreversibly, mediated by one-step chemical modification using a mercaptosilane at room temperature followed by corona treatment to realize heterogeneous assembly also at room temperature. The mercapto functional group is one of the strongest nucleophiles, and it can instantaneously react with electrophiles of substrates, resulting in an alkoxysilane-terminated substrate at room temperature. In this way, prior oxidation of the substrate is dispensed with, and the alkoxysilane-terminated substrate can be readily oxidized and irreversibly bonded with oxidized PDMS at room temperature. A commercially available Tesla coil was used for surface oxidation, replacing a bulky and expensive plasma generator. Surface characterization was conducted by water contact angle measurement and X-ray photoelectron spectroscopy (XPS) analysis. A total of fifteen non-silicon substrates including polycarbonate (PC), two types of poly(vinylchloride) (PVC), poly(methylmethacrylate) (PMMA), polystyrene (PS), polyimide (PI), two types of poly(ethylene terephthalate) (PET), polypropylene (PP), iron (Fe), aluminum (Al), copper (Cu), brass, alumina (Al2O3), and zirconia (ZrO2) were bonded successfully with PDMS using this method, and the bond strengths of PDMS-PMMA, PDMS-PC, PDMS-PVC, PDMS-PET, PDMS-Al, and PDMS-Cu assemblies were measured to be approximately 335.9, 511.4, 467.3, 476.4, 282.2, and 236.7 kPa, respectively. The overall processes including surface modification followed by surface oxidation using corona treatment for bonding were realized within 12 to 17 min for most of the substrates tested except for ceramics which required 1 h for the bonding. In addition, large area (10 × 10 cm(2)) bonding was also successfully realized, ensuring the high reliability and stability of the introduced method.
We report herein the colorimetric identification of live cells based on a nucleic acid amplification testing (NAAT) methodology using an all-in-one origami paper microdevice integrated with DNA purification, loop-mediated isothermal amplification (LAMP), and on-site colorimetric detection. First, origami paper was partially embossed to create microchannel networks and chambers. Subsequently, hydrophobic polydimethylsiloxane prepolymer was coated onto the embossed paper to stabilize the structures on paper and provide fluid barriers. The paper microdevice was composed of splitting, purification, wicking, reaction, and dye pads folded alternatively to accomplish sensitive and specific NAAT. For the viability assay, propidium monoazide (PMA) was employed to penetrate dead cells and form covalent bonds with necrotic cell DNA; thus, amplification can be solely performed with DNA obtained from live bacterial cells. Purification functionality was implemented into the microdevice using chitosan to electrostatically capture DNA. Herein, methylene blue, which is typically used for electrochemical detection, is introduced for the first time for colorimetric detection of LAMP amplicons. This origami paper microdevice was successfully applied to determine the viability of foodborne pathogens, such as Escherichia coli O157:H7 and Salmonella spp., in which amplification was performed for 30 min followed by the execution of the colorimetric method for 10 min, thereby demonstrating tremendous potential for multiplexing and versatility for point-of-care applications. The introduced origami paper microdevice could be an attractive substitute as an instantaneous and convenient screening tool for the identification of viable pathogens in the control and monitoring of foodborne outbreaks in low-resource environments.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.