Nanofabrication Technology Research Articles

Advancement in Generation and Application of Microfluidic Chip Technology

Microfluidics is an interdisciplinary topic of research that draws inspiration from other areas such as fluid dynamics, microelectronics, materials science, and physics. Microfluidics has made it possible to create microscale channels and chambers out of a broad variety of materials by borrowing ideas from a number of different fields. This has opened up exciting possibilities for the development of platforms of any size, shape, and geometry using a variety of approaches. One of the most significant advantages of microfluidics is its versatility in applications. Microfluidic chips can be used for a variety of purposes, such as incorporating nanoparticles, encapsulating and delivering drugs, targeting cells, analyzing cells, performing diagnostic tests, and cultivating cells. This adaptability has led to the development of several device-like systems for use in a range of settings. In this study, we explore cutting-edge novel applications for microfluidic and nanofabrication technologies. We examine current developments in the area of microfluidics and highlight their potential for usage in the medical industry. We pay special attention to digital microfluidics, a recently developed and very useful technique for illness diagnosis and monitoring. The originality of microfluidics is found in the fact that it allows for the miniaturization of complex systems and processes, paving the way for the creation of cutting-edge gadgets with wide-ranging practical applications. Microfluidics has the potential to transform various fields, including medicine, biotechnology, environmental monitoring, and more. The development of novel microfluidic platforms, coupled with advancements in digital microfluidics, promises to revolutionize the way we diagnose, treat, and monitor diseases.

IC Packaging Material Identification via a Hybrid Deep Learning Framework with CNN-Transformer Bidirectional Interaction.

With the advancement of micro- and nanomanufacturing technologies, electronic components and chips are increasingly being miniaturized. To automatically identify their packaging materials for ensuring the reliability of ICs, a hybrid deep learning framework termed as CNN-transformer interaction (CTI) model is designed on IC packaging images in this paper, in which several cascaded CTI blocks are designed to bidirectionally capture local and global features from the IC packaging image. Each CTI block involves a CNN branch with two designed convolutional neural networks (CNNs) for CNN local features and a transformer branch with two transformers for transformer global features and transformer local-window features. A bidirectional interaction mechanism is designed to interactively transfer the features in channel and spatial dimensions between the CNNs and transformers. Experimental results indicate that the hybrid framework can recognize three types of IC packaging materials with a good performance of 96.16% F1-score and 97.92% accuracy, which is superior to some existing deep learning methods.

Micro CT Test Pattern for Everyday Productive Use

The rapid evolution of Industrial Computed Tomography (CT) continues to raise the bar for high-resolution, accurate, and precise imaging tools. Developing effective micro CT test patterns is key to meeting these expectations. This study presents XRnanotech's advanced MicroCT test target, engineered using micro- and nano-fabrication technologies, including electron beam lithography. There are several variants; one set features various lines and spaces with dimensions as small as 200 nm and a gold contrast height of 1.5 µm for high contrast. Another set features a contrast height of approximately 4 µm, with the smallest feature sizes of 300 nm and 400 nm, respectively. The paper highlights its performance metrics, ultimately demonstrating how this innovation advances the potential of MicroCT testing.

The Intelligent Design of Silicon Photonic Devices

AbstractPhotonic devices based on silicon waveguides are essential to versatile high‐performance and low‐cost photonic integrated systems. Extremely complex silicon photonic devices with hundreds or even thousands of degrees of freedom (DOF) are successfully designed and manufactured based on recent advances in data science and nanofabrication technology. At this level, conventional forward‐reasoning may no longer be suitable for designing high‐performance silicon photonic devices with novel functionalities since the light‐matter interaction is complex and non‐intuitive. Therefore, the timely development of sub‐wavelength silicon photonic devices that can precisely mold the flow of light is a critical and urgent issue requiring joint engineering and scientific efforts. In this paper, an inverse design strategy based on heuristic and gradient descendant algorithms, enabling the realization of large‐scale integrated devices is first introduced. Subsequently, the burgeoning deep learning technology, which offers a promising direction for the automation design of silicon photonics with a data‐driven approach, is discussed. Finally, the obstacles and prospects in this emerging research direction are revealed. Detail discussions from multiple perspectives are provided. This review aims to provide general guidance and a comprehensive reference for scientists developing photonic integrated systems.

Ultra-compact electro-optic phase modulator based on a lithium niobate topological slow light waveguide.

Electro-optic modulators (EOMs) are essential devices of optical communications and quantum computing systems. In particular, ultra-compact EOMs are necessary for highly integrated photonic chips. Thin film lithium niobate materials are a promising platform for designing highly efficient EOMs. However, EOMs based on conventional waveguide structures are at a millimeter scale and challenging to scale down further, greatly hindering the capability of on-chip integration. Here, we design an EOM based on lithium niobate valley photonic crystal (VPC) structures for the first time. Due to the high effective refractive index introduced by the strong slow light effect, the EOM can achieve an ultra-compact size of 4 μm×14 μm with a half-wave voltage of 1.4 V. The EOM has a high transmittance of 0.87 in the 1068 nm because of the unique spin-valley locking effect in VPC structures. The design is fully compatible with current nanofabrication technology and immune to fabrication defects. Therefore, it opens a new possibility in designing lithium niobate electro-optic modulators and will find broad applications in optical communication and quantum photonic devices.

Wearable Microneedle Patch for Transdermal Electrochemical Monitoring of Urea in Interstitial Fluid.

Microneedle-based wearable electrochemical biosensors are the new frontier in personalized health monitoring and disease diagnostic devices that provide an alternative tool to traditional blood-based invasive techniques. Advancements in micro- and nanofabrication technologies enabled the fabrication of microneedles using different biomaterials and morphological features with the aim of overcoming existing challenges and enhancing sensing performance. In this work, we report a microneedle array featuring conductive recessed microcavities for monitoring urea levels in the interstitial fluid of the skin. Microcavities are small pockets on the tip of each microneedle that can accommodate the sensing layer, provide protection from delamination during skin insertion or removal, and position the sensing layer in a deep layer of the skin to reach the interstitial fluid. The wearable urea patch has shown to be highly sensitive and selective in monitoring urea, with a sensitivity of 2.5 mV mM-1 and a linear range of 3 to 18 mM making it suitable for monitoring urea levels in healthy individuals and patients. Our ex vivo experiments have shown that recessed microcavities can protect the sensing layer from delamination during skin insertion and monitor changing urea levels in interstitial fluid. This biocompatible platform provides alternative solutions to the critical issue of maintaining the performance of the biosensor upon skin insertion and holds great potential for advancing transdermal sensor technology.

The potential of graphene coatings as neural interfaces.

Recent advances in nanotechnology design and fabrication have shaped the landscape for the development of ideal cell interfaces based on biomaterials. A holistic evaluation of the requirements for a cell interface is a highly complex task. Biocompatibility is a crucial requirement which is affected by the interface's properties, including elemental composition, morphology, and surface chemistry. This review explores the current state-of-the-art on graphene coatings produced by chemical vapor deposition (CVD) and applied as neural interfaces, detailing the key properties required to design an interface capable of physiologically interacting with neural cells. The interfaces are classified into substrates and scaffolds to differentiate the planar and three-dimensional environments where the cells can adhere and proliferate. The role of specific features such as mechanical properties, porosity and wettability are investigated. We further report on the specific brain-interface applications where CVD graphene paved the way to revolutionary advances in biomedicine. Future studies on the long-term effects of graphene-based materials in vivo will unlock even more potentially disruptive neuro-applications.

Asymmetric contact-induced selective doping of CVD-grown bilayer WS2 and its application in high-performance photodetection with an ultralow dark current.

Two-dimensional (2D) transition metal dichalcogenides (TMDs) are excellent candidates for high-performance optoelectronics due to their high carrier mobility, air stability and strong optical absorption. However, photodetectors made with monolayer TMDs often exhibit a high dark current, and thus, there is a scope for further improvement. Herein, we developed a 2D bilayer tungsten disulfide (WS2) based photodetector (PD) with asymmetric contacts that exhibits an exceptionally low dark current and high specific detectivity. High-quality and large-area monolayer and bilayer WS2 flakes were synthesized using a thermal chemical vapor deposition system. Compared to conventional symmetric contact electrodes, utilizing metal electrodes with higher and lower work functions relative to bilayer WS2 aids in achieving asymmetric lateral doping in the WS2 flakes. This doping asymmetry was confirmed through the photoluminescence spectral profile and Raman mapping analysis. With the asymmetric contacts on bilayer WS2, we find evidence of selective doping of electrons and holes near the Ti and Au contacts, respectively, while the WS2 region away from the contacts remains intrinsic. When compared with the symmetric contact case, the dark current in the WS2 PD with asymmetric (Au, Ti) contact decreases by an order of magnitude under reverse bias with a concomitant increase in the photocurrent, resulting in an improved on/off ratio of ∼105 and overall improved device performance under identical illumination conditions. We explained this improved performance based on the energy band alignment showing a unidirectional charge flow under light illumination. Our results indicate that the planar device structure and compatibility with current nanofabrication technologies can facilitate its integration into advanced chips for futuristic low-power optoelectronic and nanophotonic applications.

Atomic layer deposition mechanism of hafnium dioxide using hafnium precursor with amino ligands and water

As a unique nanofabrication technology, atomic layer deposition (ALD) has been widely used for the preparation of various materials in the fields of microelectronics, energy and catalysis. Hafnium dioxide (HfO2), as an excellent high-κ oxide, is widely used as a substitute gate dielectric for conventional SiO2 in field effect transistor devices. Currently, HfO2 high-κ gate dielectric in MOSFET devices was prepared via ALD technology using tetrakis(dimethylamino)hafnium(IV) (Hf(NMe2)4, TDMAHf) and water (H2O) as the precursors. In this work, the complicated surface reaction mechanism of HfO2 H2O-based ALD using Hf(NMe2)4 was investigated using density functional theory calculations. In the TDMAHf reaction, the dimethylamino group of the precursor was eliminated by ligand exchange reaction with the hydroxyl group on the surface. Subsequently, a second dimethylamino group of TDMAHf could further be eliminated by another hydroxyl group on the surface. In the H2O reaction, ligand exchange reactions and coupling reactions could both occur. By the ligand exchange reactions, water molecule could react with the dimethylamino group on the surface. Simultaneously, the hydroxyl and amino groups could also react with neighboring hydroxyl groups to eliminate dimethylamine and water molecules via the coupling reactions. All these insights into the complicated surface reaction mechanism of H2O-based ALD could promote the further development of ALD chemistry and materials.

Fine-Feature Additively Dry Printed Passive Wireless Sensor Tag

Wireless passive sensors have many applications, from precision agriculture to structural health monitoring. A simple but useful wireless passive sensor tag consists of a planar inductor coupled with a planar interdigitated electrode capacitor, forming an inductor-capacitor (LC) loop. Either the planar inductor or the planar interdigitated electrode capacitor can be used as the sensor. For example, the inductor could be used for proximity detection with an external ferrous object, or the capacitor could be used to measure the relative humidity of the surrounding air. The planar inductor, however, is also used to inductively couple the sensor tag to a base station feedback oscillator. As a result, the LC loop on the sensor tag tunes the base station oscillator’s output frequency accordingly. In this work, the planar inductor and the planar interdigitated electrode capacitor were printed on a polyimide substrate using a novel laser-based additive nanomanufacturing (ANM) and dry printing technology. With this fabrication process, approximately 2 micron thick silver traces were printed to realize a 34 loop planar inductor and a 69 tooth interdigitated electrode capacitor, with a nominal trace and space width of 6 mils (152.4 microns). This recently developed laser-based ANM technique allows for much finer trace and space widths, as well as a much larger variety of electronic materials, to be printed, compared to more traditional ink-based printed electronics manufacturing techniques.

Application of nanotechnology in lithium titanate batteries

With the introduction of dual carbon policy and the development of new energy industry, new energy batteries play a pillar role in the whole industry. However, the new energy batteries made in the context of traditional cathode materials often have many defects and cannot meet the demand. This study introduces nanotechnology, lithium titanate batteries and their integrated applications. Among them, nanofabrication technology, as an emerging technology, can be used to dope new particles to modify the conventional lithium titanate to improve its own shortcomings of insufficient conductivity of a single material. The significance of this thesis is to compare each technique and each material, and to propose new experimental solutions based on the existing research results.

A Novel Method of Wireless Micro Energy Transmission Based on MEMS Micro Coil.

Based on current implantable devices, a battery's rigidity and large size makes it prone to immune rejection and wound incisions. Additionally, it is limited by its finite lifespan, which hinders long-term usage. These limitations greatly restrict the development of implantable medical device systems towards miniaturization and minimally invasive approaches. Consequently, obtaining high-fidelity and stable biological signals from the target tissue area of the organism remains challenging. Therefore, there is a need to develop wireless power transmission technology. In this paper, we propose a wireless micro energy transfer method based on MEMS micro coils for charging implantable devices. Through simulation calculations, we first investigate the influence of coaxial distance, horizontal displacement, and rotation angle between the MEMS micro coil and the transmitting coil on power transmission. Subsequently, we utilize micro nanofabrication technology to create a MEMS micro spiral copper coil with a line width, thickness, and spacing of 50 µm and a total of five turns. Finally, we conduct wireless power transmission tests on the coil. The results show that, when the transmitting coil and the receiving coil are 10 mm apart and the operating frequency is 100 kHz, the power of the wireless power transmission system reaches 45 µW. This power level is sufficient to meet the power supply requirements of implantable pacemakers. Therefore, this technology holds great potential for applications in the field of wireless power transmission for implantable medical devices, including pacemakers and brain neurostimulators.

Ultrahigh-printing-speed photoresists for additive manufacturing.

Printing technology for precise additive manufacturing at the nanoscale currently relies on two-photon lithography. Although this methodology can overcome the Rayleigh limit to achieve nanoscale structures, it still operates at too slow of a speed for large-scale practical applications. Here we show an extremely sensitive zirconium oxide hybrid-(2,4-bis(trichloromethyl)-6-(4-methoxystyryl)-1,3,5-triazine) (ZrO2-BTMST) photoresist system that can achieve a printing speed of 7.77 m s-1, which is between three and five orders of magnitude faster than conventional polymer-based photoresists. We build a polygon laser scanner-based two-photon lithography machine with a linear stepping speed approaching 10 m s-1. Using the ZrO2-BTMST photoresist, we fabricate a square raster with an area of 1 cm2 in ~33 min. Furthermore, the extremely small chemical components of the ZrO2-BTMST photoresist enable high-precision patterning, leading to a line width as small as 38 nm. Calculations assisted by characterizations reveal that the unusual sensitivity arises from an efficient light-induced polarity change of the ZrO2 hybrid. We envisage that the exceptional sensitivity of our organic-inorganic hybrid photoresist may lead to a viable large-scale additive manufacturing nanofabrication technology.

Construction of polymer nanochannels and applications in biosensors and drug delivery

In the past decade, polymer based nanochannel structures have been deeply and extensively explored due to their fast and strong sensitivity in testing ability. Recently, polymers have attracted much attention as the substrate materials of nano channels due to their excellent biocompatibility, low material cost and ease of manufacture. The development of nanochannels capable of detecting ions, small biomolecules and biomacromolecules meet the conditions of combination of multiple surface modification strategies and reliable nano manufacturing technologies. In this paper, the research progress of polymer based nanochannels is reviewed. The topic covered in this work includes the structure, manufacturing technology and functional strategy of nano channels. This review emphasizes various of promising research directions, and discusses the mechanism and principle of different applications such as biosensors and drug delivery. The shortcomings and limitations of some polymer based nano channels in the development and application are also discussed. Finally, views on the future prospects of this research field are presented.

Experimental and simulation investigation for imprinting and buckling of V-groove/wrinkles hierarchical array

With the in-depth development and continuous innovation of micro and nano manufacturing technology, flexible strain sensors are more and more widely used in various fields, including soft robots, smart clothing and so on, and high-performance sensors are more in demand. An efficient tactic for enhancing the performance of flexible strain sensors is to design and create hierarchical structures, and its efficient and controllable manufacturing is a key problem. The controllable manufacturing of V-groove/wrinkles hierarchical structure is realized by nano-imprint and prestretch-release process, which provides an effective method for large-area controllable preparation of hierarchical structure, and provides a foundation for the construction of high-performance flexible strain sensor. Single-factor experiments were carried out on the slope of the primary structure, pre-strain and substrate thickness, and response surface analysis was carried out by Box–Behnken experiments. The results of the structure’s formation are significantly influenced by the slope and substrate thickness, and the optimal process parameters are obtained by response surface analysis. Then the impact of each process parameter was investigated using a process simulation model. Finally, the forming conditions of hierarchical structure are analyzed. This study can provide guidance for the efficient and controllable manufacturing of micro/nano hierarchical structures.

Recent progress on femtosecond laser micro-/nano-fabrication of functional photonic structures in dielectric crystals: A brief review and perspective

Femtosecond (Fs) laser micro-/nano-fabrication technology allows direct definition of on-demand nanostructures with three-dimensional (3D) geometric features and tailored photonic functionalities in a facile manner. In addition, such a strategy is widely applicable to various material families, including dielectrics, semiconductors, and metals. Based on diverse dielectric crystals, fs-laser direct writing of optical waveguides with flexible geometries and functional waveguide-based photonic devices have been well-developed. Beyond waveguide architectures, the combination of 3D nanofabrication of fs lasers and the multi-functionalities of dielectric crystals has also lighted up the future development of novel photonic structures with features even beyond the optical diffraction limit. In this article, promising research topics on domain engineering for nonlinear optics, color centers and waveguides for integrated quantum photonics, and surface processing for integrated photonics enabled by fs laser micro-/nano-fabrication in dielectric crystals are briefly overviewed. We highlight recent progress on these research topics and stress the importance of optical aberration correction during laser fabrication, followed by a discussion of challenges and foreseeing the future development of fs laser defined nanostructures in dielectric crystals toward multi-functional photonics.

Suspended 2D Materials: A Short Review

In recent years, there has been a growing fascination with suspended two-dimensional (2D) materials, owing to their excellent mechanical, optical, and electronic characteristics. This surge of interest stems from the remarkable properties exhibited by these materials when they are isolated in a two-dimensional counterpart. Nanofabrication technologies provide a new platform to further explore the properties of 2D materials by suspending them to reduce the influence of substrates. In recent years, many scientists have discovered the feasibility of using suspended membranes of 2D materials in various fields, including optoelectronics and photonics. This review summarizes the recent progress in the fabrication, characterization, and applications of suspended 2D materials, focusing on critical properties such as optical and electronic properties, strain engineering, and thermal properties. This area has the potential to lead to new technologies and applications in a wide range of innovative fields.

Egyptian Blue/gold nanocomposite supramarbles, a platform for IR emission enhancement

Nanotechnology manufacturing requires a unique skillset and access to that technology is not yet within the reach of many small businesses and startups. What if a specialty product could be offered as pellets or marbles, and this new platform enabled uniform nano-coatings readily handled by off the shelf standard manufacturing technologies? The platform – a supramarble (SM) – introduced in this work is a crosslinked polymer core with a coating (or corona) of hydrophobic micro- and nanoparticles. A photoactive 2-D nanoparticulate pigment, Egyptian Blue (EB) has gained tremendous popularity in sensing applications recently due to its intense near-infrared emission at ∼900 nm. Gold nanoparticles (AuNPs) have been reported to modify the spontaneous emission of other adjacent fluorophores in a remarkable way. By combining near-infrared emitting EB microparticles and AuNP decorated fumed silica (Au-FS) NPs as the corona of an SM, significant (4-fold) fluorescence enhancement is demonstrated in this work. A maximum in fluorescent intensity was shown at 70 wt% EB and 30 wt% Au-FS composite coating. The 4-fold enhancement was attributed to AuNPs’ generation of a localized electric field synergistically interacting with the fluorescent emission of EB. The influence of Au-FS on the original, intrinsic fluorescent emission wavelength of EB (∼900 nm) was also investigated.

Supercontinuum generation in As2S3 chalcogenide waveguide pumped by all-fiber structured dual-femtosecond solitons.

Supercontinuum sources with high compactness are essential for applications such as optical sensing, airborne detection and communication systems. In the past decades, the adoption of bulky optical parametric amplifier to pump various chalcogenide glass waveguides are widely reported for on-chip mid-infrared supercontinuum generation, but this usually leads to a large volume of the whole system, and is not practical. Therefore, integrating advanced femtosecond fiber lasers with optical waveguides using nano-fabrication technology are highly desired. However, the scarcity of compact pump sources and the dispersion-matched high-nonlinearity waveguide in short wavelength regions have hindered the advancement of integrated supercontinuum source performances in the near and mid-infrared region. In this study, we demonstrate a broadband supercontinuum source from As2S3 waveguide pumped by a compact dual-femtosecond solitons pulse source. The laser is completely fiber structured, and its wavelength can be readily tuned from 2 to 2.3 µm using Raman soliton self-frequency shift technology in a Tm3+-doped fiber amplifier. Furthermore, the As2S3 waveguide is designed with controllable dispersion and high nonlinearity for a broadband supercontinuum generation. These results will advance the development of on-chip supercontinuum sources based on chalcogenide waveguides.

Exploring the potential of nano technology: A assessment of nano-scale multi-layered-composite coatings for cutting tool performance

Nano-scale Multi-layered Composite Coatings (Nano scale MLCC) offer potential benefits for cutting tool performance. Such coatings can be designed to improve tool durability and cutting efficiency by providing additional wear protection and improved heat dissipation. The Nano coatings can also be tailored to reduce friction, which can enhance productivity and reduce tool wear. The unique Nano-scale topography of MLCC helps to reduce the contact area between the cutting tool and the workpiece, thus reducing friction and heat. The coatings also include specific additive components that enhance the properties of the coating, such as corrosion resistance, lubricant retention, and improved thermal stability.This critical review explores the potential of Nano-scale multi-layered-composite coatings for improving the performance of cutting tools. The literature in this field is reviewed and discussed with respect to the performance benefits and challenges associated with the implementation of these nanotechnology coatings. The latest progress in nanofabrication, nanomaterials, and other technologies are discussed in relation to their ability to provide new and improved cutting tool applications. The review summarizes the current state of the art on Nano-scale multi-layered-composite coatings and their influence on cutting tool performance, with particular focus on machining productivity, tool life, cutting forces and wear rates. Recommendations are provided on which Nano-scale coatings may best fit the demands of particular machining operations, and on future research directions in this field. The review also discusses the challenges and future advancements of Nano-scale coatings and other methods for improving cutting tool performance. In conclusion, this review provides a comprehensive insight into the future potential of MLCC for cutting tool performance enhancement.