基于丝网印刷技术的碳纳米管场发射冷阴极制作

制备了一种新型碳纳米管浆料,并总结了一套阴极制作工艺.实验表明,质量比约为10%的纯化碳纳米管、5%的纳米金属粉末和有机材料混合形成的印刷浆料,其阴极具有较好的发射均匀特性.在浆料制备过程中通过加入表面活性剂使碳纳米管分散更加均匀.用丝网印刷技术制作阴极,并用机械刀刻的办法制作阴、栅两极之间的沟槽,经烧结后分析阴极膜的电阻率和粘附性随阴极材料组分和制作工艺的变化关系,确定较为合适的升温曲线及丝网目数,阴极碳纳米管的均匀性、导电性的提高改善了发射均匀性.该阴极开启场为2.5 V/μm,在电场强度为3.3 V/μm下,阳极电流为5.6 μA,场发射电流稳定,波动小于5%.     

Synthesis and characterization of copper ink and direct printing of copper patterns by inkjet printing for electronic devices

Among the conventional metallic inks used in the printing process, silver exhibits high conductivity and thermal stability. Nevertheless, due to the high cost of silver, it cannot be extensively used for the fabrication of inks. As a competitive alternative, copper can be considered as a substitute for silver; however, copper ink oxidizes under certain atmospheric conditions. To meet these shortcomings, a cost effective, highly conductive, and oxidation-free copper-based ink has been synthesized in this study, wherein, oxidation of the copper particles in the copper-based ink was prevented by using copper complexes. The copper ink thus fabricated was printed on chemically treated Si/SiO₂ substrates followed by the characterization of the printed copper films. The results of this study confirmed that the synthesized copper ink exhibited properties suitable for its use in the inkjet printing process for fabrication of various electronic devices.     

Patterning catalyst via inkjet printing to grow single-walled carbon nanotubes

We demonstrated a method to pattern catalyst via inkjet printing to grow SWNTs, using metal salt solutions as the inks and an ordinary office-use printer. We printed water solutions of cobalt acetate on hydrophilic Si substrates and grew high quality SWNT films.     

4D Printing based piezoelectric composite for medical applications

Additive manufacturing (AM), otherwise known as three‐dimensional (3D) printing, is driving major innovations in many areas, such as engineering, manufacturing, art, education, and medicine. Although a considerable amount of progress has been made in this field, additional research work is required to overcome various remaining challenges. Recently, one of the actively researched areas lies in the AM of smart materials and structures. Electroactive materials incorporated in 3D printing have given birth to 4D printing, where 3D printed structures can perform as actuating and/or sensing systems, making it possible to deliver electrical signals under external mechanical stimuli and vice versa. In this paper, we present a lightweight, low cost piezoelectric material based on the dispersion of inorganic ferroelectric submicron particles in a polymer matrix. We report on how the proposed material is compatible with the AM process. Finally, we discuss its potential applications for healthcare, especially in smart implants prostheses. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 109–115     

3D打印贝壳仿生复合材料的拉伸力学行为

采用硬质和软质双组分材料,通过调控两种基体材料的装配夹角,采用光固化3D打印技术制备了不同装配方式的仿贝壳珍珠层复合材料,开展了准静态拉伸实验,结合扫描电镜观察,分析了其拉伸力学性能、断裂及能量耗散机理。研究结果表明,保持胞元边长不变,随着面内装配角度增加,仿贝壳珍珠层复合材料的强度呈线性增加趋势,断裂应变呈线性减小的趋势;随着面外装配角度增大,断裂应变呈线性减小趋势,而强度在面外装配角小于45°时呈增强趋势,超过45°时趋于稳定;面外装配角度为45°时,材料的强度达到最大值。试样在断裂前主要通过硬质材料的拔出、软/硬相界面处微裂纹的生成及微裂纹在扩展过程中的合并和偏转等方式耗散能量。     

微流控纸芯片的加工及其分析应用的实验设计*

设计了一个使用喷墨打印法加工微流控纸芯片的实验,在经烷基烯酮二聚体(AKD)的正己烷溶液浸泡过的滤纸上,以三乙醇胺溶液为打印墨水,用喷墨打印机打印出设计好的芯片图案。滤纸加热后,打印区域呈现亲水性,非打印区域为疏水性,从而制备出纸芯片,用该纸芯片通过数字比色法实现了亚硝酸根离子的定量测定。该实验不使用昂贵仪器设备,易普及。通过实验,促使学生了解微流控芯片这一前沿科学技术,锻炼学生细致、灵巧的动手能力,激发学生科技创新活力。     

Cell‐Laden Hydrogels for Multikingdom 3D Printing

Living materials are created through the embedding of live, whole cells into a matrix that can house and sustain the viability of the encapsulated cells. Through the immobilization of these cells, their bioactivity can be harnessed for applications such as bioreactors for the production of high‐value chemicals. While the interest in living materials is growing, many existing materials lack robust structure and are difficult to pattern. Furthermore, many living materials employ only one type of microorganism, or microbial consortia with little control over the arrangement of the various cell types. In this work, a Pluronic F127‐based hydrogel system is characterized for the encapsulation of algae, yeast, and bacteria to create living materials. This hydrogel system is also demonstrated to be an excellent material for additive manufacturing in the form of direct write 3D‐printing to spatially arrange the cells within a single printed construct. These living materials allow for the development of incredibly complex, immobilized consortia, and the results detailed herein further enhance the understanding of how cells behave within living material matrices. The utilization of these materials allows for interesting applications of multikingdom microbial cultures in immobilized bioreactor or biosensing technologies.     

Scalable Preparation of Photochromic Composite Foils with Excellent Reversibility for Light Printing

Photochromic inks for repeatable light‐printed media have attracted increasing attention owing to the fact that they may be widely applied to reduce the consumption of papers and plastics and conserve the environment. Therefore, it is of practical significance to develop convenient photochromic inks with a low cost and on a large scale. In this study, a simple one‐step hydrothermal route was used to prepare tungsten trioxide (WO₃) nanoparticles, which were further used to make photochromic inks and transparent photochromic films. The obtained transparent photochromic film could rapidly respond to UV light within tens of seconds, then return to its initial state, with different recovery times at different temperatures, and also exhibit good reversible coloration–bleaching effect. A typical polyethylene terephthalate (PET) foil coated with the photochromic ink could also be repeatedly printed with various patterns and displayed excellent rewritable performance over tens of cycles. This study proposes a simple method for widespread applications of WO₃‐based photochromic inks.     

Synergistic Effects of Beta Tri‐Calcium Phosphate and Porcine‐Derived Decellularized Bone Extracellular Matrix in 3D‐Printed Polycaprolactone Scaffold on Bone Regeneration

Bone‐derived extracellular matrix (ECM) is widely used in studies on bone regeneration because of its ability to provide a microenvironment of native bone tissue. However, a hydrogel, which is a main type of ECM application, is limited to use for bone graft substitutes due to relative lack of mechanical properties. The present study aims to fabricate a scaffold for guiding effective bone regeneration. A polycaprolactone (PCL)/beta‐tricalcium phosphate (β‐TCP)/bone decellularized extracellular matrix (dECM) scaffold capable of providing physical and physiological environment are fabricated using 3D printing technology and decoration method. PCL/β‐TCP/bone dECM scaffolds exhibit excellent cell seeding efficiency, proliferation, and early and late osteogenic differentiation capacity in vitro. In addition, outstanding results of bone regeneration are observed in PCL/β‐TCP/bone dECM scaffold group in the rabbit calvarial defect model in vivo. These results indicate that PCL/β‐TCP/bone dECM scaffolds have an outstanding potential as bone graft substitutes for effective bone regeneration.     

A Stereolithography‐Based 3D Printed Hybrid Scaffold for In Situ Cartilage Defect Repair

Damage to articular cartilage can over time cause degeneration to the tissue surrounding the injury. To address this problem, scaffolds that prevent degeneration and promote neotissue growth are needed. A new hybrid scaffold that combines a stereolithography‐based 3D printed support structure with an injectable and photopolymerizable hydrogel for delivering cells to treat focal chondral defects is introduced. In this proof of concept study, the ability to a) infill the support structure with an injectable hydrogel precursor solution, b) incorporate cartilage cells during infilling using a degradable hydrogel that promotes neotissue deposition, and c) minimize damage to the surrounding cartilage when the hybrid scaffold is placed in situ in a focal chondral defect in an osteochondral plug that is cultured under mechanical loading is demonstrated. With the ability to independently control the properties of the structure and the injectable hydrogel, this hybrid scaffold approach holds promise for treating chondral defects.