Electrophoretic Deposition of Carbon Nanotubes on 3-Amino-Propyl-Triethoxysilane (APTES) Surface Functionalized Silicon Substrates

Optically Mediated Nonvolatile Resistive Memory Device Based on Metal-Organic Frameworks

Metal-organic frameworks (MOFs), characterized by tunable porosity, high surface area, and diverse chemical compositions, offer unique prospects for applications in optoelectronic devices. However, the prevailing research on thin-film devices utilizing MOFs has predominantly focused on aspects such as information storage and photosensitivity, often neglecting the integration of the advantages inherent in both photonics and electronics to enhance optical memory. This work demonstrates a light-mediated resistive memory device based on a highly oriented porphyrin-based MOFs film, in which the resistance state of the memristor is modulated by light, realizing the integration of the perception and storage of optical information. The memristor shows excellent performance with a wide light range of 405-785 nm and a persistent photoconductivity phenomenon up to 8.3 × 103 s. Further mechanistic studies have revealed that the resistive switching effect in the memristor is primarily associated with the reversible formation and annihilation of Ag conductive filaments.

A Miniature Biomedical Sensor for Rapid Detection of Schistosoma japonicum Antibodies

Schistosomiasis, typically characterized by chronic infection in endemic regions, has the potential to affect liver tissue and pose a serious threat to human health. Detecting and screening for this disease early on is crucial for its prevention and control. However, existing methods encounter challenges such as low sensitivity, time-consuming processes, and complex sample handling. To address these challenges, we report a soluble egg antigen (SEA)-based functionalized gridless and meander-type AlGaN/GaN high electron mobility transistors (HEMT) sensor for the highly sensitive detection of antibodies to Schistosoma japonicum. Immobilization of the self-assembled membrane on the gate surface was verified using a semiconductor parameter analyzer, scanning electron microscope (SEM), and atomic force microscopy (AFM). The developed biosensor demonstrates remarkable performance in detecting anti-SEA, exhibiting a linear concentration range of 10 ng/mL to 100 μg/mL and a sensitivity of 0.058 mA/log (ng/mL). It also exhibits similar excellent performance in serum systems. With advantages such as rapid detection, high sensitivity, miniaturization, and label-free operation, this biosensor can fulfill the requirements for blood defense.

Conventional and emerging strategies for the fabrication and functionalization of PDMS-based microfluidic devices

Microfluidics is an emerging and multidisciplinary field that is of great interest to manufacturers in medicine, biotechnology, and chemistry, as it provides unique tools for the development of point-of-care diagnostics, organs-on-chip systems, and biosensors. Polymeric microfluidics, unlike glass and silicon, offer several advantages such as low-cost mass manufacturing and a wide range of beneficial material properties, which make them the material of choice for commercial applications and high-throughput systems. Among polymers used for the fabrication of microfluidic devices, polydimethylsiloxane (PDMS) still remains the most widely used material in academia due to its advantageous properties, such as excellent transparency and biocompatibility. However, commercialization of PDMS has been a challenge mostly due to the high cost of the current fabrication strategies. Moreover, specific surface modification and functionalization steps are required to tailor the surface chemistry of PDMS channels (e.g. biomolecule immobilization, surface hydrophobicity and antifouling properties) with respect to the desired application. While significant research has been reported in the field of PDMS microfluidics, functionalization of PDMS surfaces remains a critical step in the fabrication process that is difficult to navigate. This review first offers a thorough illustration of existing fabrication methods for PDMS-based microfluidic devices, providing several recent advancements in this field with the aim of reducing the cost and time for mass production of these devices. Next, various conventional and emerging approaches for engineering the surface chemistry of PDMS are discussed in detail. We provide a wide range of functionalization techniques rendering PDMS microchannels highly biocompatible for physical or covalent immobilization of various biological entities while preventing non-specific interactions.

Preparation of defected SWCNTs decorated with en-APTAS for application in high-performance nitric oxide gas detection

We demonstrate highly sensitive and selective chemiresistive-type NO gas detection using defected single-walled carbon nanotubes (SWCNTs) decorated with N-[3-(trimethoxysilyl)propyl]ethylene diamine (en-APTAS) molecules. The defected SWCNTs were prepared via furnace annealing at 700 °C and confirmed by transmission electron microscopy. A single en-APTAS molecule has two amine groups acting as adsorption sites for NO gas, which can improve the NO response. The NO response was further enhanced when the defected SWCNTs were utilized because NO sensing reactions could occur on both the inner and outer walls of the defected SWCNTs. The en-APTAS decoration improved the NO response of the SWCNT-based gas sensing devices by 2.5 times; when the defected SWCNTs were used, the NO response was further improved by 3 times. Meanwhile, the recovery performance in a time-resolved response curve was significantly improved (45 times) via a simple rinsing process with ethanol. Specifically, the fabricated device did not respond to carbon monoxide (CO) or BTEX gas (i.e., a mixture of benzene, toluene, ethyl benzene, and xylene), indicating its high selectivity to NO gas. The results show the possibility of a high-performance SWCNT-based NO gas sensor applicable to healthcare fields requiring ppb-level detection, such as in vitro diagnostics (IVDs) of respiratory diseases.

Selective Chemistry-Based Separation of Semiconducting Single-Walled Carbon Nanotubes and Alignment of the Nanotube Array Network under Electric Field for Field-Effect Transistor Applications

Semiconducting single-walled carbon nanotubes (s-SWCNTs) are considered as a replacement for silicon in field-effect transistors (FETs), solar cells, logic circuits, and so forth, because of their outstanding electronic, optical, and mechanical properties. Herein, we have studied the reaction of pristine SWCNTs dispersed in a pluronic F-68 (PF-68) polymer solution with para-amino diphenylamine diazonium sulfate (PADDS) to separate nanotubes based on their metallicity. The preferential selectivity of the reactions was monitored by changes in the semiconducting (S22 and S33) and metallic (M11) bands by ultraviolet-visible-near infrared spectroscopy. Metallic selectivity depended on the concentrations of PADDS, reaction time, and the solution pH. Furthermore, separation of pure s-SWCNTs was confirmed by Raman spectroscopy and Fourier-transform infrared spectroscopy. After the removal of metallic SWCNTs, direct current electric field was applied to the pure s-SWCNT solution, which effectively directed the nanotubes to align in one direction as nanotube arrays with a longer length and high density. After that, electrically aligned s-SWCNT solution was cast on a silicon substrate, and the length of the nanotube arrays was measured as ∼2 to ∼14 μm with an areal density of ∼2 to ∼20 tubes/μm of s-SWCNTs. Next, electrically aligned s-SWCNT arrays were deposited on the channel of the FET device by drop-casting. Field-emission scanning electron microscopy and electrical measurements have been carried out to test the performance of the aligned s-SWCNTs/FETs. The fabricated FETs with a channel length of 10 μm showed stable electrical properties with a field-effect mobility of 30.4 cm2/Vs and a log10 (I on/I off) current ratio of 3.96. We envisage that this new chemical-based separation method and electric field-assisted alignment could be useful to obtain a high-purity and aligned s-SWCNT array network for the fabrication of high-performance FETs to use in digital and analog electronics.

Fabrication of Zinc Oxide Nanoparticles Deposited on (3-Aminopropyl) Triethoxysilane-Treated Silicon Substrates by an Optimized Voltage-Controlled Electrophoretic Deposition and Their Application as Fluorescence-Based Sensors

In this study, a voltage controlled, reproducible, scalable, and cost-effective approach for depositing zinc oxide (ZnO) nanoparticles (NPs), using electrophoretic deposition (EPD) onto p-type silicon (Si) substrates, has been researched and analyzed for its feasibility with respect to electronic device fabrication and fluorescence-based sensors. Our work presents a detailed investigation to evaluate the influence of ZnO morphology, ZnO concentration, and the method of surface treatment applied to the underlying Si substrates, because these pertain to an optimized EPD system. It has been noted that the ZnO NP structures formed directly atop the (3-aminopropyl) triethoxysilane (APTES)-treated Si substrates were more adhesive, thus resulting in a higher yield of NPs over that of comparable depositions on bare silicon. Our observation is that smaller particle sizes of ZnO will increase the energy emission for fluorescence transmission, eliminate several peak emissions, obtain higher fluorescence quantum yield (FQY) efficiency, and require less excitation energy. The results obtained are promising in relation to the integration of EPD in the fabrication of nano biosensors, PV solar cells, nano electronic devices, and thin film transistors (TFTs), where ZnO improves the reliability, affordability, and increased sensitivity needed for the next generation of nanoscale devices and systems.

Processing Methods Used in the Fabrication of Macrostructures Containing 1D Carbon Nanomaterials for Catalysis

A large number of methodologies for fabrication of 1D carbon nanomaterials have been developed in the past few years and are extensively described in the literature. However, for many applications, and in particular in catalysis, a translation of the materials to a macro-structured form is often required towards their use in practical operation conditions. This review intends to describe the available methods currently used for fabrication of such macro-structures, either already applied or with potential for application in the fabrication of macro-structured catalysts containing 1D carbon nanomaterials. A review of the processing methods used in the fabrication of macrostructures containing 1D sp2 hybridized carbon nanomaterials is presented. The carbon nanomaterials here discussed include single- and multi-walled carbon nanotubes, and several types of carbon nanofibers (fishbone, platelet, stacked cup, etc.). As the processing methods used in the fabrication of the macrostructures are generally very similar for any of the carbon nanotubes or nanofibers due to their similar chemical nature (constituted by stacked ordered graphene planes), the review aggregates all under the carbon nanofiber (CNF) moniker. The review is divided into methods where the CNFs are synthesized already in the form of a macrostructure (in situ methods) or where the CNFs are previously synthesized and then further processed into the desired macrostructures (ex situ methods). We highlight in particular the advantages of each approach, including a (non-exhaustive) description of methods commonly described for in situ and ex situ preparation of the catalytic macro-structures. The review proposes methods useful in the preparation of catalytic structures, and thus a number of techniques are left out which are used in the fabrication of CNF-containing structures with no exposure of the carbon materials to reactants due to, for example, complete coverage of the CNF. During the description of the methodologies, several different macrostructures are described. A brief overview of the potential applications of such structures in catalysis is also offered herein, together with a short description of the catalytic potential of CNFs in general.

Facile Photo-cross-linking System for Polymeric Gate Dielectric Materials toward Solution-Processed Organic Field-Effect Transistors: Role of a Cross-linker in Various Polymer Types

Energy-efficient solution-processed organic field-effect transistors (OFETs) are highly sought after in the low-cost printing industry as well as for the manufacture of flexible and other next-generation devices. The fabrication of such electronic devices requires high-functioning insulating materials that are chemically and mechanically robust to avoid lowering insulating properties during the device fabrication process or utilization of devices. In this study, we report a facile, fluorinated, UV-assisted cross-linker series using a fluorophenyl azide (FPA), which reacts with the C-H groups of a conventional polymer. This demonstrates the application of the cross-linked films in OFET gate dielectrics. The effects of the cross-linkable chemical structure of the FPA series on the cross-linking chemistry, photopatternability, and dielectric properties of the resulting films are investigated for low/high-k or amorphous/crystalline polymeric gate dielectric materials. The characteristics of insulating layers and behavior of OFETs containing these cross-linked gate dielectrics (for example, leakage current density (J), hysteresis, and charge trap density) depend on the polymer type. Furthermore, an organic-based complementary inverter and various printable OFETs with excellent electrical characteristics are successfully fabricated. Thus, these reported cross-linkers that enable the solution process and patterning of well-developed conventional polymer dielectric materials are promising for the realization of a more sustainable next-generation industrial technology for flexible and printable devices.

Computational Study of APTES Surface Functionalization of Diatom-like Amorphous SiO2 Surfaces for Heavy Metal Adsorption

The amorphous silica (SiO₂) shell on diatom frustules is a highly attractive biomaterial for removing pollutants from aquatic ecosystems. The surface activity of silica can be enhanced by modification with organosilanes. In this work, we present an atomic-level theoretical study based on molecular dynamics and dispersion-corrected density functional theory calculations on the surface stability and adsorption of heavy metal (HM) compounds on silane- and 3-aminopropyltriethoxysilane (APTES)-covered SiO₂ surfaces. Our simulations show that at low APTES coverage, the molecular adsorption of Cd(OH)₂ and HgCl₂ is more favorable near the modifier, compared to As(OH)₃ that binds at the hydroxylated region on silica. At higher coverages, the metallic compounds are preferentially adsorbed by the terminating amino group on the surface, whereas the adsorption in the region between APTES and the oxide surface is also spontaneous. The adsorption is strongly driven by van der Waals interactions at the highly covered surface, where the consideration of dispersion corrections reduces the modifier-adsorbate interatomic distances and increases the adsorption energy by ca. 0.4-0.7 eV. The adsorption of water is favorable, although it is generally weaker than for the HM compounds. Based on our results, we conclude that the addition of APTES modifiers on silica increases the adsorption strength and provides extra binding sites for the adsorption of HM pollutants. These outcomes can be used for the design of more efficient structures of biomaterials for depollution of HMs.

Controllable Electrically Guided Nano-Al/MoO3 Energetic-Film Formation on a Semiconductor Bridge with High Reactivity and Combustion Performance

Film-forming techniques and the control of heat release in micro-energetic chips or devices create challenges and bottlenecks for the utilization of energy. In this study, promising nano-Al/MoO3 metastable intermolecular composite (MIC) chips with an uniform distribution of particles were firstly designed via a convenient and high-efficiency electrophoretic deposition (EPD) technique at room temperature and under ambient pressure conditions. The mixture of isopropanol, polyethyleneimine, and benzoic acid proved to be an optimized dispersing agent for EPD. The kinetics of EPD for oxidants (Al) and reductants (MoO3) were systematically investigated, which contributed to adjusting the equivalence ratio of targeted energetic chips after changing the EPD dynamic behaviors of Al and MoO3 in suspension. In addition, the obtained nano-Al/MoO3 MIC energetic chips showed excellent heat-release performance with a high heat release of ca. 3340 J/g, and were successfully ignited with a dazzling flame recorded by a high-speed camera. Moreover, the fabrication method here is fully compatible with a micro-electromechanical system (MEMS), which suggests promising potential in designing and developing other MIC energetic chips or devices for micro-ignition/propulsion applications.

CRISPR/dCas9 platforms in plants: strategies and applications beyond genome editing

Clustered regularly interspaced short palindromic repeat (CRISPR) and Cas9-associated protein systems provide a powerful genetic manipulation tool that can drive plant research forward. Nuclease-dead Cas9 (dCas9) is an enzymatically inactive mutant of Cas9 in which its endonuclease activity is non-functional. The applications of CRISPR/dCas9 have expanded and diversified in recent years. Originally, dCas9 was used as a CRISPR/Cas9 re-engineering tool that enables targeted expression of any gene or multiple genes through recruitment of transcriptional effector domains without introducing irreversible DNA-damaging mutations. Subsequent applications have made use of its ability to recruit modifying enzymes and reporter proteins to DNA target sites. In this paper, the most recent progress in the applications of CRISPR/dCas9 in plants, which include gene activation and repression, epigenome editing, modulation of chromatin topology, live-cell chromatin imaging and DNA-free genetic modification, will be reviewed. The associated strategies for exploiting the CRISPR/dCas9 system for crop improvement with a dimer of the future of the CRISPR/dCas9 system in the functional genomics of crops and the development of traits will be briefly discussed.

Functionalized Leather: a Novel and Effective Hazardous Solid Waste Adsorbent for the Removal of the Diazo Dye Congo Red from Aqueous Solution

The leather industry produces a high yield of solid hazardous wastes that generate a major impact on the environment. At the same time, the use of dyes by different manufacturing industries, including the footwear industry, creates large amounts of colored wastewater that is hard to treat. In this paper, potential adsorbents based on the functionalization of solid waste from leather in the removal of anionic dye Congo Red were studied. Twelve different functionalized adsorbents were analyzed in terms of dye removal. From those, the best adsorbents were characterized and tested to determine their life cycle, pH dependency and the resulting phytotoxicity of the treated dye baths. Different kinetic models were evaluated to describe this adsorption process. It was found that functionalized leather adsorbents presented multi-linearity behavior when removing Congo Red. Life cycle analysis showed that the adsorbents presented a high yield of absorption until the third cycle of operation, while phytotoxicity tested showed reductions up to 50% in the toxicity of the treated dye baths.

Recent Development in Separators for High-Temperature Lithium-Ion Batteries

Lithium-ion batteries (LIBs) are promising energy storage devices for integrating renewable resources and high power applications, owing to their high energy density, light weight, high flexibility, slow self-discharge rate, high rate charging capability, and long battery life. LIBs work efficiently at ambient temperatures, however, at high-temperatures, they cause serious issues due to the thermal fluctuation inside batteries during operation. The separator is a key component of batteries and is crucial for the sustainability of LIBs at high-temperatures. The high thermal stability with minimum thermal shrinkage and robust mechanical strength are the prime requirements along with high porosity, ionic conductivity, and electrolyte uptake for highly efficient high-temperature LIBs. This Review deals with the recent studies and developments in separator technologies for high-temperature LIBs with respect to their structural layered formation. The recent progress in monolayer and multilayer separators along with the developed preparation methodologies is discussed in detail. Future challenges and directions toward the advancement in separator technology are also discussed for achieving remarkable performance of separators in a high-temperature environment.

Tailoring Interfacial Properties by Controlling Carbon Nanotube Coating Thickness on Glass Fibers Using Electrophoretic Deposition

The electrophoretic deposition (EPD) method was used to deposit polyethylenimine (PEI) functionalized multiwall carbon nanotube (CNT) films onto the surface of individual S-2 glass fibers. By varying the processing parameters of EPD following Hamaker's equation, the thickness of the CNT film was controlled over a wide range from 200 nm to 2 μm. The films exhibited low electrical resistance, providing evidence of coating uniformity and consolidation. The effect of the CNT coating on fiber matrix interfacial properties was investigated through microdroplet experiments. Changes in interfacial properties due to application of CNT coatings onto the fiber surface with and without a CNT-modified matrix were studied. A glass fiber with a 2 μm thick CNT coating and the unmodified epoxy matrix showed the highest increase (58%) in interfacial shear strength (IFSS) compared to the baseline. The increase in the IFSS was proportional to CNT film thickness. Failure analysis of the microdroplet specimens indicated higher IFSS was related to fracture morphologies with higher levels of surface roughness. EPD enables the thickness of the CNT coating to be adjusted, facilitating control of fiber/matrix interfacial resistivity. The electrical sensitivity provides the opportunity to fabricate a new class of sizing with tailored interfacial properties and the ability to detect damage initiation.

Inkjet Printing of Carbon Nanotubes

In an attempt to give a brief introduction to carbon nanotube inkjet printing, this review paper discusses the issues that come along with preparing and printing carbon nanotube ink. Carbon nanotube inkjet printing is relatively new, but it has great potential for broad applications in flexible and printable electronics, transparent electrodes, electronic sensors, and so on due to its low cost and the extraordinary properties of carbon nanotubes. In addition to the formulation of carbon nanotube ink and its printing technologies, recent progress and achievements of carbon nanotube inkjet printing are reviewed in detail with brief discussion on the future outlook of the technology.