An overview of thermoelectric films:Fabrication techniques,classification,and regulation methods

Thermoelectric materials have aroused widespread concern due to their unique ability to directly convert heat to electricity without any moving parts or noxious emissions.Taking advantages of two-dimensional structures of thermoelectric films,the potential applications of thermoelectric materials are diversified,particularly in microdevices.Well-controlled nanostructures in thermoelectric films are effective to optimize the electrical and thermal transport,which can significantly improve the performance of thermoelectric materials.In this paper,various physical and chemical approaches to fabricate thermoelectric films,including inorganic,organic,and inorganic–organic composites,are summarized,where more attentions are paid on the inorganic thermoelectric films for their excellent thermoelectric responses.Additionally,strategies for enhancing the performance of thermoelectric films are also discussed.

Photoelectrochemical CO_(2) electrolyzers: From photoelectrode fabrication to reactor configuration

The photoelectrochemical conversion of CO_(2) into value-added products emerges as an attractive approach to alleviate climate change. One of the main challenges in deploying this technology is, however, the development and optimization of(photo)electrodes and photoelectrolyzers. This review focuses on the fabrication processes, structure, and characterization of(photo)electrodes, covering a wide range of fabrication techniques, from rudimentary to automated fabrication processes. The work also highlights the most relevant features of(photo)electrodes, with special emphasis on how to measure and optimize them. Finally, the review analyses the integration of(photo)electrodes in different photoelectrolyzer architectures, analyzing the most recent research work that comprises photocathode, photoanode,photocathode-photoanode, and tandem photoelectrolyzer configurations to ideally achieve self-sustained CO_(2) conversion systems. Overall, comprehensive guidelines are provided for future advancements in developing effective devices for CO_(2) conversion, bridging the gap towards the use of sunlight as the unique energy input and practical applications.

The journey of multifunctional bone scaffolds fabricated from traditional toward modern techniques

As a bone scaffold,meeting all basic requirements besides dealing with other bone-related issues-bone cancer and accelerated regeneration-is not expected from traditional scaffolds,but a newer class of scaffolds called multifunctional.From a clinical point of view,being a multifunctional scaffold means reducing in healing time,direct costs-medicine,surgery,and hospitalization-and indirect costs-loss of mobility,losing job,and pain.The main aim of the present review is following the multifunctional bone scaffolds trend to deal with both bone regeneration and cancer therapy.Special consideration is given to different fabrication techniques which have been applied to yield these materials spanning from traditional to modern ones.Moreover,the hierarchical structure of bone plus bone cancers and available medicines to them are introduced to familiarize the potential reader of review with the pluri-disciplinary essence of the field.Eventually,a brief discussion relating to the future trend of these materials is provided.

Low-damage photolithography for magnetically doped(Bi,Sb)_(2)Te_(3) quantum anomalous Hall thin films

We have developed a low-damage photolithography method for magnetically doped(Bi,Sb)_(2)Te_(3)quantum anomalous Hall(QAH) thin films incorporating an additional resist layer of poly(methyl methacrylate)(PMMA). By performing control experiments on the transport properties of five devices at varied gate voltages(V_(g)s), we revealed that the modified photolithography method enables fabricating QAH devices with the transport and magnetic properties unaffected by fabrication process. Our experiment represents a step towards the production of novel micro-structured electronic devices based on the dissipationless QAH chiral edge states.

Fabrication of micro-nano patterned materials mimicking the topological structure of extracellular matrix for biomedical applications

With the advent of tissue engineering and biomedicine,the creation of extracellular matrix(ECM)biomaterials for in vitro applications has become a prominent and promising strategy.These ECM materials provide physical,biochemical,and mechanical properties that guide cellular behaviors,such as proliferation,differentiation,migration,and apoptosis.Because micro-and nano-patterned materials have a unique surface topology and low energy replication process that directly affect cellular biological behaviors at the interface,the fabrication of micro-nano pattern biomaterials and the regulation of surface physical and chemical properties are of great significance in the fields of cell regulation,tissue engineering,and regenerative medicine.Herein,we provide a comprehensive review of the progress in the fabrication and application of patterned materials based on the coupling of mechanical action at the micro-and nano-meter scale,including photolithography,micro-contact printing,electron beam lithography,electrospinning,and 3D printing technology.Furthermore,a summary of the fabrication process,underlying principles,as well as the advantages and disadvantages of various technologies are reviewed.We also discuss the influence of material properties on the fabrication of micro-and nano-patterns.

Microstructures and mechanical properties of titanium-reinforced magnesium matrix composites: Review and perspective

Currently, many gratifying signs of progress have been made in magnesium(Mg) matrix composites(MMCs) by virtue of their high mechanical properties both at room and elevated temperatures. Although the commonly used reinforcements in MMCs are ceramic particles,they often provide improved yield and ultimate stresses by a significant loss in ductility. Therefore, hard metallic phases were introduced as alternative candidates for the manufacturing of MMCs, especially titanium(Ti). It has a high melting point, high Young’s modulus, high plasticity, low level of mutual solubility with Mg matrix, and closer thermal expansion coefficient to that of Mg metal than that of ceramic particles. It is highly preferable to provide both high ultimate stress and ductility in Mg matrix. However, many critical challenges for the fabrication of Ti-reinforced MMCs remain, such as Ti’s homogeneity, low recovery rate, and the optimization of interfacial bonding strength between Mg and Ti, etc. Meanwhile, different fabrication methods have various effects on the microstructures, mechanical properties, and the interfacial strength of Ti-reinforced MMCs. Hence, this review placed emphasis on the microstructural characteristics and mechanical properties of Ti-reinforced MMCs fabricated by different techniques. The influencing factors that govern the strengthening mechanisms were systematically compared and discussed. Future research trends, key issues, and prospects were also proposed to develop Ti-reinforced MMCs.

Recent advances in the design of biosensors based on novel nanomaterials:An insight

Biosensors have acquired much importance in drug discovery,medical diagnostics,food safety,defense,security,and monitoring of environmental conditions.Furthermore,there has been great progress in the potential applications of advanced nanomaterials in biosensors.Every year there are several advances in sensing techniques that can be attributed to nanomaterials,biorecognition elements,or their related fabrication techniques.The further development of nanotechnology-based sensors provides a wide variety of opportunities to modern research.Advanced nanomaterials can provide remarkable optical,electrical,mechanical,and catalytic properties.For example,transition metals and organic polymers have been used in the fabrication of powerful,sensitive,and precise biosensors.The distinctive properties of advanced nanomaterials have been widely incorporated into biosensors.However,fabrication techniques also play important roles in the development of these devices.Therefore,we present a review of some of the advanced nanomaterials that have been widely used over the last few years and discuss their fabrication techniques.The focus of this review is to provide a directional perspective of recently fabricated advanced nanomaterial-based biosensors in the diagnosis of various diseases.

Integrated gradient tissue-engineered osteochondral scaffolds:Challenges,current efforts and future perspectives

The osteochondral defect repair has been most extensively studied due to the rising demand for new therapies to diseases such as osteoarthritis.Tissue engineering has been proposed as a promising strategy to meet the demand of simultaneous regeneration of both cartilage and subchondral bone by constructing integrated gradient tissue-engineered osteochondral scaffold(IGTEOS).This review brought forward the main challenges of establishing a satisfactory IGTEOS from the perspectives of the complexity of physiology and microenvironment of osteochondral tissue,and the limitations of obtaining the desired and required scaffold.Then,we comprehensively discussed and summarized the current tissue-engineered efforts to resolve the above challenges,including architecture strategies,fabrication techniques and in vitro/in vivo evaluation methods of the IGTEOS.Especially,we highlighted the advantages and limitations of various fabrication techniques of IGTEOS,and common cases of IGTEOS application.Finally,based on the above challenges and current research progress,we analyzed in details the future perspectives of tissue-engineered osteochondral construct,so as to achieve the perfect reconstruction of the cartilaginous and osseous layers of osteochondral tissue simultaneously.This comprehensive and instructive review could provide deep insights into our current understanding of IGTEOS.

Flexible inorganic piezoelectric functional films and their applications

Piezoelectric materials play an increasingly important role in energy harvesters,sensors,and actuators.Flexible and thin piezoelectric films have been demonstrated to provide advanced functionalities and improved performances.However,the research on flexible inorganic piezoelectric thin films has rarely been systematically summarized.Here,we summarize the recent advances in the flexible inorganic piezoelectric thin films,focusing on their structural designs,fabrication techniques,and applications in various practical scenarios.Specifically,different fabrication techniques suitable for diverse inorganic piezoelectric nanostructures are reviewed,including sol-gel,hydrothermal,electrospinning,and other techniques,and the integration process with flexible substrates is further discussed.Biomedical and industrial applications of the flexible piezoelectric thin films are emphasized.Finally,some existing challenges and future perspectives are discussed.

Composites for electric vehicles and automotive sector: A review

The automotive sector is undergoing a significant transformation to address critical challenges affecting consumers and the climate.One of the most difficult tasks is reducing the weight of vehicles in order to minimize energy consumption.A ten percent decrease in curb weight is predicted to result in a six to eight percent reduction in energy consumption.Composite materials having better strength to weight ratio are one of the finest options for planning,designing and manufacturing of the lightweight components.In automobile sector,employment of composite materials would reduce the weight of electric vehicles as well as influence their aerodynamic properties.Therefore,it would decrease the consumption of fuel as well by cutting down harmful emissions and particulate matter.Numerous developments in such technologies are studied over the last decade by automobile establishments and academic researchers.Fiber-reinforced polymers,particularly those established on glass and carbon fibers,have attracted attention of the automobile sector due to their high performance and lesser weight.This paper reviews the applications of various types of composite materials and the fabrication techniques of such composites in electric vehicles and automobiles.Furthermore,a comprehensive data breakdown of the lightweight materials statistics and figures on market analysis of high performance composite is presented.Finally,a discussion is made on the different applications of these composites.Hence,the details presented in this study should be useful for automobile companies to align with NET ZERO global mission while sustaining their businesses.

Preparation and application of gallium-based conductive materials in the very recent years

Gallium and its alloys are a group of metallic materials with low-melting points at or around room temperature.Apart from the good electrical conductivity,the unique liquid state endows those metals with excellent compliance and self-healing capacity,which present great value in the development of flexible and stretchable electronics.Constrained by the high surface tension and low viscosity,however,liquid metals cannot be applied to some common microelectronics manufacturing technologies such as micro-electro mechanics in the preceding years,which impedes their mass production in electronic devices.To address these issues and broaden the applications of liquid metals in electronics devices,numerous efforts have been taken and great progress has been made especially in the very recent years.This review summaries the recent development of liquid metal-based conductive materials from the aspects of preparation or modification methods and their accommodative fabrication techniques in flexible electronic applications.Further outlook including expectations and challenges of liquid metal-based conductive materials are also presented.

Reply to Comments on "Structural,Optical,and Electrical Properties of Zn-Doped CdO Thin Films Fabricated by a Simplified Spray Pyrolysis Technique'' by K.Usharani and A.R.Balu published in Acta Metall.Sin.(Engl.Lett.) 28(1),64–71(2015)

Following are the comments for the queries raised by Prof. Pawel E. Tomaszewski on our published paper entitled ＂Structural, Optical, and Electrical Properties of Zn-Doped CdO Thin Films Fabricated by a Simplified Spray Pyrolysis Technique＂ by K. Usharani and A.R. Balu published in Acta Metall. Sin.

Bismuth-doped germanate glass fiber fabricated by the rod-in-tube technique

Bismuth （Bi）-doped laser glasses and fiber devices have aroused wide attentions due to their unique potential to work in the new spectral range of 1 to 1.8 μm traditional laser ions, such as rare earth, cannot reach. Current Bi-dopcd silica glass fibers have to be made by modified chemical vapor deposition at a temperature higher than 2000℃. This unavoidably leads to the tremendous loss of Bi by evaporation, since the temperature is several hundred degrees Celsius higher than the Bi boiling temperature, and, therefore, trace Bi （-50 ppm） resides within the final product of silica fiber. So, the gain of such fiber is usually extremely low. One of the solutions is to make the fibers at a temperature much lower than the boiling temperature of Bi. The challenge for this is to find a lower melting point glass, which can stabilize Bi in the near infrared emission center and, meanwhile, does not lose glass transparency during fiber fabrication. None of previously reported Bi-doped multicomponent glasses can meet the prerequisite. Here, we, after hundreds of trials on optimization over glass components, activator content, melting temperature, etc., find a novel Bi-doped gallogermanate glass, which shows good tolerance to thermal impact and can accommodate a higher content of Bi. Consequently, we successfully manu- facture the germanate fiber by a rod-in-tube technique at 850℃. The fiber exhibits similar luminescence to the bulk glass, and it shows saturated absorption at 808 nm rather than 980 nm as the incident power becomes higher than 4 W. Amplified spontaneous emissions are observed upon the pumps of either 980 or 1064 nm from ger- manate fiber.

Comments on "Structural,Optical,and Electrical Properties of Zn-Doped CdO Thin Films Fabricated by a Simplified Spray Pyrolysis Technique'' by K.Usharani and A.R.Balu Published in Acta Metall.Sin.(Engl.Lett.) 28(1),64–71(2015)

The commented paper [1] presents the results on structural, optical, and electrical properties of Zn-doped CdO thin films. Unfortunately, there are several mistakes and errors not found by any of referees. It is necessary to show these mistakes or misleading statements to avoid their use in the future papers by authors and other peoples.