Glass Devices Research Articles

High-refractive-index glass device fabricated by room temperature bonding

Abstract Wafer bonding is an essential technology for attaching various materials, including glass. Glass-glass bonding has been applied to fabricate glass micro/nanofluidic devices that work as analytical tools for chemical and biological research. Here, we report the fabrication of micro/nanofluidic devices consisting of a high refractive index (HRI) glass as a component of the device for the first time. Although HRI glass has been used for high-sensitivity and high-resolution imaging in microscopy, it has not been used for glass fluidic devices due to the lack of bonding method for HRI glass. The glass fluidic devices were made through glass-glass bonding at room temperature, which could avoid severe damage to bonded substrates of two glass types due to different rates of thermal expansion. The pressure endurance of these devices was measured to find the correlation with the surface properties of glass substrates. The measured results indicated that chemical groups other than SiOH enhanced the pressure endurance of the devices. Thus, these chemical groups helped to form the fluidic devices consisting of HRI glass and another glass type, borosilicate or fused silica, to achieve practical pressure endurance up to 270 kPa. The HRI glass-incorporating device showed 8-fold higher sensitivity and 30 % narrower spatial resolution of fluorescence signals than the other devices with non-HRI glass.

Electropolishing of complex-shaped bulk metallic glasses in NaCl-ethylene glycol electrolyte

Electropolishing (EP) has been widely used to obtain good surface roughness of metallic structures; however, precisely-shaped cathodes are still necessary for the EP of bulk metallic glass (BMG) devices and components. In this work, the EP behavior of a Zr-based BMG was investigated using a plain steel cathode in NaCl-ethylene glycol electrolyte. The recast layer of wire electrical discharge machined (WEDMed) BMG surfaces with crystallization was effectively removed through the EP process, restoring the surface properties of BMGs. The effects of processing parameters, such as voltage, temperature, time, and electrolyte concentration, on the EP performance were explored, and the optimal EP parameters were determined. The EP mechanisms were discussed, where pitting formation was found to consist of three stages. Finally, the EP of a curved BMG part was successfully achieved based on the optimized processing parameters, further validating the feasibility to electropolish complex-shaped BMG structures using direct current (DC) power and NaCl-ethylene glycol electrolyte.

Universal and Versatile Magnetic Connectors for Microfluidic Devices

World-to-chip interfacing remains a critical issue for microfluidic devices. Current solutions to connect tubing to rigid microfluidic chips remain expensive, laborious, or require specialized skills and precision machining. Here, we report reusable, inexpensive, and easy-to-use connectors that enable monitoring of the connection ports. Our magnetic connectors benefit from a simple one-step fabrication process and low dead volume. They sustain pressures within the high range of microfluidic applications. They represent an essential tool for rapid thermoplastic (PMMA, PC, COC) prototyping and can also be used with glass, pressure-sensitive adhesive, or thin PDMS devices.

Innovative retrofitting approaches for energy saving in Saudi public schools

Saudi buildings use approximately 29% of the primary energy and about 80% of the electrical energy. Because of the hot and dry climate, air conditioners consume a lot of electrical energy to attain a comfortable temperature indoors. More than 70% of Saudi buildings need to be thermally insulated. The objective of this study is to assess the existing energy saving of public schools in Saudi Arabia. Indoor thermal environment monitoring of three school buildings has been undertaken by employing LSI LASTEM ‘R-LOG’ data loggers, and electric energy bills of the schools were also collected. The school building was modelled using DesignBuilder software, which was utilized to investigate the impact of various modifications made to the building envelopes, including changes to building orientation, the inclusion of thermal insulation layers, various types of glass and shading devices. According to the findings, implementing appropriate building envelope design techniques for existing schools can lead to significant reductions in cooling and overall energy consumption, with savings of 30% and 19%, respectively. After applying these strategies collectively, the school managed to reduce its total annual electricity consumption by nearly 19.2%, resulting in a decrease from 279.13 MWh to 225.5 MWh per year.

Droplet-based fluorescence anisotropy insulin immunoassay.

Over the last several decades, multiple microfluidic platforms have been used for measurement of hormone secretion from islets of Langerhans. Most have used continuous flow systems where mixing of hormones with assay reagents is governed by diffusion, leading to long mixing times, especially for biomolecules like peptides and proteins which have large diffusion coefficients. Consequently, dispersion of rapidly changing signals can occur, reducing temporal resolution. Droplet microfluidic systems can be used to capture reagents into individual reactors, limiting dispersion and improving temporal resolution. In this study, we integrated a fluorescence anisotropy (FA) immunoassay (IA) for insulin into a droplet microfluidic system. Insulin IA reagents were mixed online with insulin and captured quickly into droplets prior to passing through a 200 mm incubation channel. Double etching of the glass device was used to increase the depth of the incubation channel compared to the IA channels to maintain proper flow of reagents. The droplet system produced highly precise FA results with relative standard deviations < 2% at all insulin concentrations tested, whereas the absolute fluorescence intensity precisions ranged between 5 and 6%. A limit of detection of 3 nM for insulin was obtained, similar to those found in conventional flow systems. The advantage of the system was in the increased temporal resolution using the droplet system where a 9.8 ± 2.6 s response time was obtained, faster than previously reported continuous flow systems. The improved temporal resolution aligns with continued efforts to resolve rapid signaling events in pancreatic islet biology.

Bessel beams as a versatile tool to generate embedded devices in optical glasses

Beam shaping offers many opportunities to both streamline and accelerate laser fabrication processes, closing the gap between lab research and large-scale manufacturing. In the field of embedded devices, a Bessel beam configuration allows for large volume engraving of transparent materials in a single laser pass. In this work, we take advantage of femtosecond Bessel beams with a length of 340 μm and a diameter of 1 μm to generate diffractive elements within three distinct optical glasses. This strategy represents a chemical-free and cost-effective alternative to the conventional manufacturing of holographic elements based on photoresist micro-patterning. Despite the different nonlinear effects taking place in each material, we report the successful fabrication of diffraction gratings operating at either normal or Bragg incidence, with efficiencies in the first combined order of up to 70%. Our experimental results show the potential of Bessel beams as a tool to produce buried light devices in a wide variety of glass materials.

The use of foam glass to protect the degrading permafrost soils

The article is devoted to the study of the use of foam glass to prevent the degradation of permafrost soils due to climate warming. In the Frost 3D software, for the conditions of Norilsk, a foam glass device for thermal insulation of a base composed of clayey soils, as well as transformed with the help of crushed stone or foam glass columns, was modeled without taking into account the thermal influence of the building. In addition, the insulation of the soils of the base transformed by columns in the ventilated underground of a new (in Yakutsk) and existing (in Norilsk) buildings designed according to the I principle of construction on permafrost soils was investigated. The forecast of the temperature distribution in the ground frozen base without taking into account the thermal influence of the building showed that in conditions of climate warming, the installation of thermal insulation of the base with the use of foam glass allows to reduce the thickness of the seasonally thawed layer by 0.3…0.4 m and reduce the temperature of permafrost. Foam glass can be used for thermal insulation of weak soil bases transformed with the help of crushed stone columns, as well as, in the future, as a material for the columns themselves. For a new building on a base transformed by crushed stone columns, covering the surface of the ventilated underground with a heat-insulating foam glass material during the warm season made it possible to significantly reduce the thickness of the seasonally thawed layer (by 0.9 m). The numerical simulation has shown the effectiveness of the use of foam glass to prevent the degradation of permafrost soils due to climate warming. Foam glass is a promising material for the development of technological measures that ensure the operability of the bases and foundations of buildings and structures at permafrost in the conditions of climate change.

Assessing Surface Adsorption in Cyclic Olefin Copolymer Microfluidic Devices Using Two-Dimensional Nano Liquid Chromatography-Micro Free Flow Electrophoresis Separations.

Surface interactions are a concern in microscale separations, where analyte adsorption can decrease the speed, sensitivity, and resolution otherwise achieved by miniaturization. Here, we functionally characterize the surface adsorption of hot-embossed cyclic olefin copolymer (COC) micro free-flow electrophoresis (μFFE) devices using two-dimensional nLC × μFFE separations, which introduce a 3- to 5 s plug of analyte into the device and measure temporal broadening that arises from surface interactions. COC is an attractive material for microfluidic devices, but little is known about its potential for surface adsorption in applications with continuous fluid flow and temporal measurements. Adsorption was minimal for three small molecule dyes: positively charged rhodamine 123, negatively charged fluorescein, and neutral rhodamine 110. Temporal peak widths for the three dyes ranged from 3 to 7 s and did not change significantly with increasing transit distance. Moderate adsorption was observed for Chromeo P503-labeled myoglobin and cytochrome c with temporal peak widths around 20 s. Overall, the COC surface adsorption was low compared to traditional glass devices, where peak widths are on the order of minutes. Improvements in durability, long-term performance, and ease of fabrication, combined with low overall adsorption, make the COC μFFE devices a practical choice for applications involving time-resolved continuous detection.

Shivalik Plasma Device-I, a glow discharge device to study the collective dynamics of dusty plasma

Using a uniquely configured glow discharge-based Shivalik Plasma Device-I, we demonstrate a variety of collective phenomena in dusty plasma away from the glow discharge region. The cylindrical glass device produces plasma using parallel disc-shaped electrodes with a smaller anode size than the cathode. The dust microparticles are initially sprinkled over the grounded cathode. These particles acquire a significant negative charge upon plasma formation, resulting in their levitation due to the balance between the Coulomb force and gravity. The new device supports the levitation of a big-sized (10 × 8 × 5 cm3) three-dimensional dust cloud over the glass surface. It contrasts the dusty plasma formations in-between electrodes reported earlier. As the discharge voltage varies from high to low, the dust cloud travels from over the glass surface to between the electrodes. A complex interplay of dust void over the cathode, a sharp density gradient, and gravity lead to self-excitation of collective dust phenomena. It includes dust density waves (phase velocity, vph ∼ 4 cm/s), dust cloud oscillation (frequency, f = 5 Hz), sheared flow (flow velocity, vf ∼ 1 cm/s), and multiple-sized dust vortices. These dust vortices provided an excellent platform for studying turbulent mixing phenomena. The power spectrum analysis agreed with two-dimensional Kolmogorov power-law scaling. This is an ideal dusty plasma apparatus where we can create or move the dust cloud to a location of choice from the glass surface to in-between the electrodes and excite one among many collective dust dynamics.

Glass Devices for Next-Generation Packaging and RF Signal Conditioning

The push for higher communications frequencies, greater system integration, and smaller space imparts many unique challenges on RF and packaging engineers in the development of next generation cellular products for 5G, WiFi 6, Military, and other applications. Traditional materials, such as LTCC, organic laminates, and silicon face major limitations to dramatically improve system size, weight, and performance (SWAP). Photosensitive Glass-Ceramics (PSG) have gained a lot of attention as a next generation RF and RF packaging substrate for their ability to simultaneously solve these two important challenges. In this paper the authors will present on our work using PSG for RF and RF packaging solutions. We will share (1) the advantages of using PSG for advanced RF packages, and (2) our work demonstrating glass as an RF substrate integrating discrete components and embedded die for passive RF filters, and (3) our work towards building vertically stacked glass packages for advanced RF systems-in-package (SiP). The described work presents a manufacturing platform for the production of vertically stacked glass substrates with integrated high Quality Factor passive devices, such as inductors and capacitors, and heterogeneously integrated surface mount devices for advanced RF systems-in-package. The presented material demonstrates a production and assembly process for the manufacturing of advanced systems. In this paper, we present design, production, assembly considerations that impact size, weight, and performance (SWAP) metrics for a variety of product definitions and multiple simulation vs. product testing to demonstrate a reliable design to product flow.

Fabrication of µFFE Devices in COC via Hot Embossing with a 3D-Printed Master Mold.

The fabrication of high-performance microscale devices in substrates with optimal material properties while keeping costs low and maintaining the flexibility to rapidly prototype new designs remains an ongoing challenge in the microfluidics field. To this end, we have fabricated a micro free-flow electrophoresis (µFFE) device in cyclic olefin copolymer (COC) via hot embossing using a PolyJet 3D-printed master mold. A room-temperature cyclohexane vapor bath was used to clarify the device and facilitate solvent-assisted thermal bonding to fully enclose the channels. Device profiling showed 55 µm deep channels with no detectable feature degradation due to solvent exposure. Baseline separation of fluorescein, rhodamine 110, and rhodamine 123, was achieved at 150 V. Limits of detection for these fluorophores were 2 nM, 1 nM, and 10 nM, respectively, and were comparable to previously reported values for glass and 3D-printed devices. Using PolyJet 3D printing in conjunction with hot embossing, the full design cycle, from initial design to production of fully functional COC µFFE devices, could be completed in as little as 6 days without the need for specialized clean room facilities. Replicate COC µFFE devices could be produced from an existing embossing mold in as little as two hours.

Multilevel resistive switching memory in lead-free double perovskite La_{2}NiFeO_{6} films

Dense and flat La_{2}NiFeO_{6} (LNFO) films were fabricated on the indium tin oxide-coated glass (ITO/glass) substrate by sol–gel method. The bipolar resistive switching behavior (BRS) could be maintained in 100 cycles and remained after 30 days, indicating that the LNFO-based RS device owned good memory stability. Surprisingly, the multilevel RS characteristics were firstly observed in the Au/LNFO/ITO/glass device. The high resistance states (HRSs) and low resistance state (LRS) with the maximum ratio of sim 500 could be remained stably in 900 s and 130 cycles, demonstrating the fine retention and endurance ability of this LNFO-based RS device. The BRS behavior of Au/LNFO/ITO/glass devices primarily obeyed the SCLC mechanism controlled by oxygen vacancies (OVs) dispersed in the LNFO layer. Under the external electric field, injected electrons were captured or discharged by OVs during trapping or detrapping process in the LNFO layer. Thus, the resistive state switched between HRS and LRS reversibly. Moreover, the modulation of Schottky-like barrier formed at the Au/LNFO interface was contributed to the resistive states switchover. It was related to the change in OVs located at the dissipative region near the Au/LNFO interface. The multilevel RS ability of LNFO-based devices in this work provides an opportunity for researching deeply on the high density RS memory in lead-free double perovskite oxides-based devices.

Transparent and Robust Superhydrophobic Structure on Silica Glass Processed with Microstereolithography Printing.

Silica glass devices are widely used due to their exceptional physical and chemical properties. However, prolonged usage may result in abrasion and contamination of silica glass devices, adversely affecting the service life. One of the most effective solutions to this issue is surface modification, in which superhydrophobicity with high transmittance and mechanical robustness is highly desired. Inspired by the concept of protective armor, we proposed a novel approach for the direct integration of robust and transparent superhydrophobic structures on silica glass. In this method, microstereolithography synergistic heat treatment processes are used to create a micrometer-scale biomimetic frame on the surface of silica glass and then filled with in situ deposited nanoparticles. The superhydrophobicity of the surface can be obtained through the nanoparticles, and the biomimetic frame can protect the surface from direct contact with external objects to achieve durability. This process allows the preparation of superhydrophobic silica structures on the silica device surface at temperatures below its melting point, which prevents any damage to the devices during the heat treatment. Moreover, up to 90% transmittance does not affect the performance of silica devices. The composite structure maintains a contact angle of over 150° after multiple abrasion tests, verifying the mechanical robustness. This innovative process paves the way for forming a high mechanical robustness and excellent transmittance protective layer on silica glass devices, which expands the application field.

Dual‐Function Near‐Infrared Emitting Aerogel‐Based Device for Detection and Sunlight‐Driven Photodegradation of Antibiotics: Realizing the Processability of Silsesquioxane‐Based Fluorescent Porous Materials

AbstractIt is highly desirable to develop facile methods to improve the processability of porous materials for industrial applications. Herein, the preparation of a novel near‐infrared emitting hybrid aerogel (PCS‐CA) is reported by physically blending a porous material with chitosan. The applied porous material (PCS‐CZ‐O‐DCM) is obtained from a near‐infrared emission semiconductor compound (CZ‐O‐DCM) and octavinylsilsesquioxane (OVS). PCS‐CZ‐O‐DCM can detect tetracycline hydrochloride selectively and rapidly in various solution with an extremely low detection limit of 0.29 µm for fluorescence quenching. It also exhibits an outstanding sunlight‐driven photodegradation activity for antibiotics even in the absence of additional oxidation agents or pH control. PCS‐CA also performs better than PCS‐CZ‐O‐DCM powder. A PCS‐CA‐based glass device is further fabricated, which enables a larger amount of water purification of antibiotics by a continuous flow‐through system by light‐driven degradation. By blending with a soft polymer matrix, improved processability can be applied to insoluble porous materials. As a result, a novel functional devices can be realized which provides a new way to apply insoluble porous materials.

Development of microfluidic devices for on-site water quality testing using glass molding process

The demand for multi-point water quality monitoring is increasing to solve the global problem of safe drinking water supply and environmental water contamination by industries. Therefore, compact devices are needed for on-site water quality analysis. On-site devices require low cost and high durability because they are placed outdoors, exposing them to strong ultraviolet rays and a wide range of temperatures. Our previous study reported on a compact and low-cost water quality meter that uses microfluidic devices with resin to monitor chemicals. In this study, we extended the fabrication range of the glass molding method to fabricate a glass microfluidic device with a 300 µm deep channel on a 50 mm in diameter substrate for constructing a low-cost and high-durability device. Finally, we developed a low-cost, highly robust glass device with a diamond-like carbon-coated channel surface to measure residual chlorine. The experimental results indicated that this device can endure outdoor conditions and be attached to small internet of things devices for analyzing chemical substances, such as residual chlorine.Graphical

The annealing temperature dependence of the RRAM effect and the oxygen vacancy mechanism for double perovskite Bi2FeCrO6 film

Resistive random access memory (RRAM) is the most potentially nonvolatile memory of the next generation. In this paper, the double perovskite Bi2FeCrO6 (BFCO) thin films were prepared on FTO/glass using the sol-gel method. And, the resistive switching (RS) phenomena were observed in the Au/BFCO/FTO/glass device annealed at different temperatures. Moreover, the RS behaviors and the mechanism of the Au/BFCO/FTO device were analyzed and discussed, and the RS behaviors could be due to the interaction between the interfacial barrier and oxygen vacancies, and the change of RRAM performance under the annealing temperatures can be attributed to the crystallinity and oxygen vacancy defect content in double perovskite BFCO films, so that, the largest and most stable switching ratios of more than 102 for the BFCO film is achieved annealed at 700 °C. These findings will help us design and fabricate the multiferroic BFCO-based resistive switching memory devices.

RF Glass Technology Is Going Mainstream: Review and Future Applications

Driven by the increasing demand for high-throughput communication links and high-resolution radar sensors, the development of future wireless systems pushes at ever greater operating frequencies. By analogy, high-performance computing (HPC) systems with high-bandwidth I/Os have become a mainstream solution to address multi Gbit/s data rates. Heterogeneous integration technologies play a vital role here in enhancing the performance and functional density, along with reducing the size and costs of such RF systems. In line with this trend, many passive components, which have once been monolithically integrated, are now implemented on ceramic or polymer-based packages. Besides these long-established material and process technologies, considerable efforts have also recently been devoted to the development of RF components on glass and glass-ceramics. Spurred by their low dielectric losses, extremely smooth surfaces, and excellent dimensional stability, glass technologies are emerging as a promising alternative for high-volume and high-performance RF applications. In this article, relevant glass materials and key enabling technologies are reviewed and put into context with well-established RF substrate technologies. Another focus is set on the latest glass-based packaging and interposer solutions ranging from MHz-to-THz frequencies. To showcase the development activities and practical accomplishments of the RF glass technology, also a large variety of key components is presented. Finally, the paper concludes by discussing future research and development directions of RF glass devices.

Smart Glasses for Supporting Distributed Care Work: Systematic Review.

Over the past 2 decades, various desktop and mobile telemedicine systems have been developed to support communication and care coordination among distributed medical teams. However, in the hands-busy care environment, such technologies could become cumbersome because they require medical professionals to manually operate them. Smart glasses have been gaining momentum because of their advantages in enabling hands-free operation and see-what-I-see video-based consultation. Previous research has tested this novel technology in different health care settings. The aim of this study was to review how smart glasses were designed, used, and evaluated as a telemedicine tool to support distributed care coordination and communication, as well as highlight the potential benefits and limitations regarding medical professionals' use of smart glasses in practice. We conducted a literature search in 6 databases that cover research within both health care and computer science domains. We used the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) methodology to review articles. A total of 5865 articles were retrieved and screened by 3 researchers, with 21 (0.36%) articles included for in-depth analysis. All of the reviewed articles (21/21, 100%) used off-the-shelf smart glass device and videoconferencing software, which had a high level of technology readiness for real-world use and deployment in care settings. The common system features used and evaluated in these studies included video and audio streaming, annotation, augmented reality, and hands-free interactions. These studies focused on evaluating the technical feasibility, effectiveness, and user experience of smart glasses. Although the smart glass technology has demonstrated numerous benefits and high levels of user acceptance, the reviewed studies noted a variety of barriers to successful adoption of this novel technology in actual care settings, including technical limitations, human factors and ergonomics, privacy and security issues, and organizational challenges. User-centered system design, improved hardware performance, and software reliability are needed to realize the potential of smart glasses. More research is needed to examine and evaluate medical professionals' needs, preferences, and perceptions, as well as elucidate how smart glasses affect the clinical workflow in complex care environments. Our findings inform the design, implementation, and evaluation of smart glasses that will improve organizational and patient outcomes.

Understanding droplet breakup in a post-array device with sheath-flow configuration.

Microfluidic post-array devices have the potential to generate quasi-monodisperse emulsion droplets with high throughput and dispersed phase fractions by splitting droplets with regularly arranged posts. However, the lack of understanding of post-array devices makes it challenging to predict droplet size and quantitatively evaluate the influence of post geometry, hindering their widespread application. Therefore, we investigated the characteristics of droplet breakup through a post array using a series of devices with sheath-flow configurations, in which the dispersed and continuous flow rates could be flexibly tuned. Using a poly(dimethylsiloxane)-glass device fabricated via soft lithography, we found that the volume ratio of the dispersed phase to the continuous phase significantly affects the droplet size, even when the viscosity ratio is close to one. For the first time, we demonstrated that the effective capillary number calculated from the emulsion viscosity and effect of the dispersed phase fraction consistently describes various experimental results. Furthermore, our flow observations and droplet diameter measurement showed two breakup modes: the size-constant obstruction and shear-induced modes with a power-law correlation similar to droplet splitting in a T-junction. Thus, the power-law correlation in microfluidic droplet splitting successfully expresses the droplet generation characteristics in post-array devices. A combination of effective viscosity correction and curve fitting allowed us to evaluate the influence of the material and post-geometry on droplet generation characteristics. This study contributes to the understanding of droplet breakup in post-array devices and extends their unique droplet generation properties to include high-throughput, high-fraction, robust, and continuous emulsification processes.

Is the replacement of “Pb” by “Cu” in methylammonium lead bromide possible?

Substitution of hazardous “Lead” by environmentally benign “Copper” in the methylammonium lead bromide perovskite system is investigated in this work. Nanostructured CH3NH3Pb1-xCuxBr3 perovskite thin films exhibiting c-axis growth has been achieved by us. Evidence for c-axis growth in the copper substituted thin films were obtained from HRTEM analysis. Using a two-step process sequence consisting of a non-aqueous emulsion-based technique for nano-power synthesis followed by a drop-cast technique was optimized for thin film growth. Structural and optical characterizations confirmed the formation of copper substituted methylammonium lead bromide in the orthorhombic structure with preferential orientation along the (040) plane. The average grain size was estimated to be ∼20 nm. Optical characterization identified the optical band gap to be ∼2.46 eV with characteristic green photoluminescence at ∼534 nm. Photo response was obtained from a Glass/FTO/CH3NH3Pb1-xCuxBr3/Graphite/FTO/Glass device structure engineered by us. The photosensitivity of the device structure was observed to be 1299 which was nearly an order above the photosensitivity of the pristine counterpart.