智能材料助力实现微纳尺度操控

At the macroscopic world,we often take the manipulation of objects in our environment for granted.However,at the micro/nanoscale,the precise and controlled alteration,handling,or actuation(i.e.,manipulation)of materials and structures are highly challenging and different due to the scaling effects and increased complexity of dominant interaction forces at these length scales[1],requiring new materials and methods.

Fabrication of practical deformable displays:advances and challenges

Display form factors such as size and shape have been conventionally determined in consideration of usability and portability.The recent trends requiring wearability and convergence of various smart devices demand innovations in display form factors to realize deformability and large screens.Expandable displays that are foldable,multi-foldable,slidable,or rollable have been commercialized or on the edge of product launches.Beyond such two-dimensional(2D)expansion of displays,efforts have been made to develop three dimensional(3D)free-form displays that can be stretched and crumpled for use in realistic tactile sensation,artificial skin for robots,and on-skin or implantable displays.This review article analyzes the current state of the 2D and 3D deformable displays and discusses the technological challenges to be achieved for industrial commercialization.

3D bioprinted organ-on-chips

Organ-on-a-chip(OOC)platforms recapitulate human in vivo-like conditions more realistically compared to many animal models and conventional two-dimensional cell cultures.OOC setups benefit from continuous perfusion of cell cultures through microfluidic channels,which promotes cell viability and activities.Moreover,microfluidic chips allow the integration of biosensors for real-time monitoring and analysis of cell interactions and responses to administered drugs.Three-dimensional(3D)bioprinting enables the fabrication of multicell OOC platforms with sophis-ticated 3D structures that more closely mimic human tissues.3D-bioprinted OOC platforms are promising tools for understanding the functions of organs,disruptive influences of diseases on organ functionality,and screening the efficacy as well as toxicity of drugs on organs.Here,common 3D bioprinting techniques,advantages,and limitations of each method are reviewed.Additionally,recent advances,applica-tions,and potentials of 3D-bioprinted OOC platforms for emulating various human organs are presented.Last,current challenges and future perspectives of OOC plat-forms are discussed.

Metal matrix nanocomposites in tribology: Manufacturing, performance, and mechanisms

Metal matrix nanocomposites(MMNCs)become irreplaceable in tribology industries,due to their supreme mechanical properties and satisfactory tribological behavior.However,due to the dual complexity of MMNC systems and tribological process,the anti-friction and anti-wear mechanisms are unclear,and the subsequent tribological performance prediction and design of MMNCs are not easily possible:A critical up-to-date review is needed for MMNCs in tribology.This review systematically summarized the fabrication,manufacturing,and processing techniques for high-quality MMNC bulk and surface coating materials in tribology.Then,important factors determining the tribological performance(mainly anti-friction evaluation by the coefficient of friction(CoF)and anti-wear assessment with wear rate)in MMNCs have been investigated thoroughly,and the correlations have been analyzed to reveal their potential coupling/synergetic roles of tuning tribological behavior of MMNCs.Most importantly,this review combined the classical metal/alloy friction and wear theories and adapted them to give a(semi-)quantitative description of the detailed mechanisms of improved anti-friction and anti-wear performance in MMNCs.To guarantee the universal applications of these mechanisms,their links with the analyzed influencing factors(e.g.,loading forces)and characteristic features like tribo-film have been clarified.This approach forms a solid basis for understanding,predicting,and engineering MMNCs’tribological behavior,instead of pure phenomenology and experimental observation.Later,the pathway to achieve a broader application for MMNCs in tribo-related fields like smart materials,biomedical devices,energy storage,and electronics has been concisely discussed,with the focus on the potential development of modeling,experimental,and theoretical techniques in MMNCs’tribological processes.In general,this review tries to elucidate the complex tribo-performances of MMNCs in a fundamentally universal yet straightforward way,and the discussion and summary in this review for the tribological performance in MMNCs could become a useful supplementary to and an insightful guidance for the current MMNC tribology study,research,and engineering innovations.