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One-step bonding and hydrophobic surface modification method for rapid fabrication of polycarbonate-based droplet microfluidic chips
摘要： Chip bonding and hydrophobic surface modification are two critical processes for the fabrication of a droplet microfluidic chip from the thermoplastic polycarbonate (PC) material. In this paper, we describe a novel one-step method, which simultaneously bonded and modified two PC substrates. The mechanism of this one-step method is that n-pentane acts as a sacrificial solvent and acetone is the solvent that bonds the PC substrates. Additionally, entrapment functionalization and the Si-O-Si cross-linked network play a central role in the hydrophobic surface modification process. The method was optimized to achieve a high bonding strength, low surface roughness, and high optical transmittance. The naturally hydrophilic PC substrate surface was modified to become a hydrophobic surface, with surface tension decreased from 33.6 mN/m to 14.8 mN/m. Monodisperse droplets generated using a droplet generation chip fabricated by this method had an average diameter of 101.3 μm and coefficient of variation of 0.55%. A droplet digital polymerase chain reaction experiment was successfully carried out using droplets generated from this chip, which demonstrated the effectiveness of this method. This novel one-step method holds great potential for manufacturing droplet-based microfluidic chips using PC in large-scale, and it may have broad applications in microfluidic research fields.
关键词： chip bonding,droplet digital PCR,entrapment functionalization,droplet microfluidics,hydrophobic surface modification
更新于2025-09-10 09:29:36
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Hydrogen-Bonded Two-Component Ionic Crystals Showing Enhanced Long-Lived Room-Temperature Phosphorescence via TADF-Assisted F?rster Resonance Energy Transfer
摘要： Molecular room-temperature phosphorescent (RTP) materials with long-lived excited states have attracted widespread attention in the fields of optical imaging, displays, and sensors. However, accessing ultralong RTP systems remains challenging and examples are still limited to date. Herein, a thermally activated delayed fluorescence (TADF)-assisted energy transfer route for the enhancement of persistent luminescence with an RTP lifetime as high as 2 s, which is higher than that of most state-of-the-art RTP materials, is proposed. The energy transfer donor and acceptor species are based on the TADF and RTP molecules, which can be self-assembled into two-component ionic salts via hydrogen-bonding interactions. Both theoretical and experimental studies illustrate the occurrence of effective F?rster resonance energy transfer (FRET) between donor and acceptor molecules with an energy transfer efficiency as high as 76%. Moreover, the potential for application of the donor–acceptor cocrystallized materials toward information security and personal identification systems is demonstrated, benefitting from their varied afterglow lifetimes and easy recognition in the darkness. Therefore, the work described in this study not only provides a TADF-assisted FRET strategy toward the construction of ultralong RTP, but also yields hydrogen-bonding-assembled two-component molecular crystals for potential encryption and anti-counterfeiting applications.
关键词： thermally activated delayed fluorescence,energy transfer,cocrystallization,hydrogen bonding self-assembly,room-temperature phosphorescence
更新于2025-09-10 09:29:36
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Molecularly imprinted photonic hydrogel sensor for optical detection of L-histidine
摘要： A molecularly imprinted photonic hydrogel (MIPH) is described for the optical determination of L-histidine (L-His). The inverse opal structure of MIPH was obtained by placing silica particles (230 nm) in molecularly imprinted polymer on a glass slide. After being fully etched by hydrofluoric acid, this inverse opal structure brings about a high specific surface and plentiful binding sites for L-His. If L-His is absorbed by the modified MIPH, its average effective refraction coefficient is increased. This causes the Bragg diffraction peak to be red-shifted by about 34 nm as the concentration of L-His increases from 0 to 100 nM. Much smaller diffraction peak shifts are obtained for other amino acids. The detection limit of this method is 10 pM. The response time towards L-His is as short as 60 s. In addition, the sensor can be recovered by treatment with 0.1 M acetic acid/methanol. It was applied to the determination of L-His in drinks sample.
关键词： Inverse opal structure,St?ber method,Nanoporous materials,Photonic crystal array,UV curing,Bragg diffraction peak,Hydrogen bonding,Reflection spectrum
更新于2025-09-10 09:29:36
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[IEEE 2018 IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits (IPFA) - Singapore (2018.7.16-2018.7.19)] 2018 IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits (IPFA) - Evaluation of the Thermal Properties for the Design of the Semiconductor Device
摘要： The more semiconductor devices progress, the more importance of caring about heat dissipation from heat generation increase. This is called “Thermal design”. Thermophysical property values like thermal conductivity and thermal expansion coefficient are used as information for thermal design. The specified values in a brochure or literature data of similar materials are usually used as the thermophysical property values for the thermal design. However, when those values are used for simulation, the results may be wrong because an actual measured value such as rate of conduction of heat of an ingredient is different from literature data or the nominal value in many cases. It is thought that there are a lot of cases without considering directionality of an ingredient (anisotropy) and influence of joint interface. We propose that we should measure these values with considering anisotropy, size effect and the bonding state and utilize them for thermal design of electronic materials used in a semiconductor device.
关键词： Thermal diffusivity,Thermal conductivity,Thin film,Thermal resistance,Bonding layer,Anisotropy,Thermal design,Transient thermal measurement
更新于2025-09-10 09:29:36
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<i>(Invited)</i> Water Transport Along Si/Si Direct Wafer Bonding Interfaces
摘要： The transport of water in a highly confined gap made by the direct bonding of low roughness silicon hydrophilic wafers is studied. We derive the equation for the transport of water from chemical potential gradients, using Stokes and conservation equations. The transport equation is found to be a Porous Medium Equation with exponent 2. A solution for this equation with stepwise boundary conditions is given. The model is tested against different initial conditions for inward and outward flow, and different temperatures and humidity levels.
关键词： silicon direct bonding,chemical potential gradients,Porous Medium Equation,water transport,hydrophilic wafers
更新于2025-09-10 09:29:36
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Molecular dynamics simulation and experimental verification for bonding formation of solid-state TiO2 nano-particles induced by high velocity collision
摘要： Collision processes of solid-state nano-sized ceramic particles were investigated by molecular dynamics (MD) simulation in order to clarify their bonding mechanisms. Effect of particle temperature on particle bonding formation was examined, and collision behavior of nano-sized TiO2 particle was discussed in terms of particle deformations. Microstructures and bonding qualities of bonded nano-sized TiO2 particles induced by high velocity collision were examined by high resolution transmission electron microscope (HR-TEM) to verify the MD results. Simulation results demonstrate that the bonding formation of nano-sized TiO2 particles can be attributed to the atomic displacement and lattice distortion in localized impact region of particle boundaries. TEM microstructure results prove simulation results and indicate effective chemical bonding formations between nano-particles at low temperature by high velocity collision. Quantitative results show that the high temperature is beneficial to the particle bonding formation. The asperity around nano-sized ceramic particles surface contributes to the displacement and lattice distortion in localized impact region under the high impact compressive pressure. The fact demonstrates a new mechanism of nano-scale ceramic particle bonding formation induced by the localized atomic displacement. The study present opens up a promising prospect of fabricating functional equipment with nano-scale ceramic particles with high velocity collision at ambient temperature.
关键词： Atomic displacement,MD simulation,Nano-ceramic particle,HR-TEM,Chemical bonding
更新于2025-09-10 09:29:36
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Driving chemical interactions at graphene-germanium van der Waals interfaces via thermal annealing
摘要： Despite its extraordinary charge carrier mobility, the lack of an electronic bandgap in graphene limits its utilization in electronic devices. To overcome this issue, researchers have attempted to chemically modify the pristine graphene lattice in order to engineer its electronic bandstructure. While significant progress has been achieved, aggressive chemistries are often employed which are difficult to pattern and control. In an effort to overcome this issue, here we utilize the well-defined van der Waals interface between crystalline Ge(110) and epitaxial graphene to template covalent chemistry. In particular, by annealing atomically pristine graphene-germanium interfaces synthesized by chemical vapor deposition under ultra-high vacuum conditions, chemical bonding is driven between the germanium surface and the graphene lattice. The resulting bonds act as charge scattering centers that are identified by scanning tunneling microscopy. The generation of atomic-scale defects is independently confirmed by Raman spectroscopy, revealing significant densities within the graphene lattice. The resulting chemically modified graphene has the potential to impact next-generation nanoelectronic applications.
关键词： graphene,van der Waals interfaces,germanium,Raman spectroscopy,chemical bonding,scanning tunneling microscopy,thermal annealing
更新于2025-09-10 09:29:36
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Direct wafer bonding of Ga2O3–SiC at room temperature
摘要： Integration of Ga2O3 on SiC substrate with a high thermal conductivity is one of the promising solutions to reduce the self-heating of Ga2O3 devices. Direct wafer bonding of Ga2O3–SiC at room temperature was achieved by surface activated bonding (SAB) using a Si-containing Ar ion beam. An average bonding energy of ~2.31 J/ m2 was achieved. Both the structure and the composition of the interface were investigated to understand the bonding mechanism. According to the interface analysis, a ~2.2 nm amorphous SiC layer and a ~1.8 nm amorphous β-Ga2O3 layer originating from the ion beam bombardment for surface activation were found at the interface. A slight di?usion at the interface might already happen at room temperature, which should contribute to the strong bonding. To con?rm the di?usion at a low temperature and investigate the possible interfacial variation during device operation, an annealing process was carried out at 473 K. The same analysis was applied on the annealed bonding interface. The interfacial layer shrank by ~0.5 nm after annealing. The further di?usion of Ga and Si at the interface caused by the annealing was con?rmed. Besides, the position of the Ar count peak inside the amorphous Ga2O3 layer shifted by ~0.5 nm toward SiC.
关键词： Ga2O3,Room temperature,Direct wafer bonding,SiC
更新于2025-09-10 09:29:36
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Pressureless joining of SiC ceramics at low temperature
摘要： Pressureless joining of SiC ceramics at low temperature was developed using Ti powder interlayer. Phase assemblage and microstructure of SiC joint revealed that the products after diffusion bonding mainly consisted of Ti5Si3 and TiC owing to the comparatively low joining temperature. Additionally, Si and C elements were found to be with higher penetration depth in the Ti interlayer. Benefitting from the lower proportion of the brittle Ti5Si3 phase and porosity, shear strength reached a relatively higher value of 41 MPa after joining at 1200oC for 30 min.
关键词： SiC ceramics,Shear strength,Ti powder,Diffusion bonding,Pressureless joining
更新于2025-09-10 09:29:36
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SOI wafer fabricated with a diamond BOX layer using surface activated bonding at room temperature
摘要： We propose a fabrication process for a silicon on insulator (SOI) wafer with a diamond buried oxide (BOX) layer by combining nanodiamond-seeding deposition and a surface-activated bonding technique for high-frequency and power device applications. The diamond layer was deposited on a base wafer by the spin-coating of nanodiamonds and microwave-plasma-enhanced chemical vapor deposition. The thermal conductivity of this deposited diamond layer was three times that of a conventional SiO2 layer. A silicon wafer was then bonded to the diamond layer at room temperature in ultrahigh vacuum without forming any voids. Additionally, this SOI wafer was used to fabricate devices at 1000 °C. Therefore, we believe that this SOI wafer with a diamond BOX layer and its fabrication process are important for the realization of self-heating devices such as next-generation high-frequency and power devices.
关键词： SOI wafer,surface-activated bonding,high-frequency devices,power devices,diamond BOX layer
更新于2025-09-10 09:29:36