基于MEMS技术的自呼吸式微型直接甲醇燃料电池

报道了一种利用MEMS技术制作的微型直接甲醇燃料电池.其特点在于,利用KOH体硅腐蚀和双面光刻工艺制作了一种独特的三维自吸氧阴极结构.分析了MEMS制作工艺的改进.实验结果表明,该电池室温下产生了2.52mW/cm2的最大功率.此性能好于国外报道的同类基于MEMS技术制作的被动式微型直接甲醇燃料电池,并同本课题组之前报道的需使用外部泵的主动式微型直接甲醇燃料电池性能相当,证明了文中提出的新结构的可行性.     

硅基微型直接甲醇燃料电池的研究

设计了一种基于MEMS技术的硅基微型直接甲醇燃料电池(DMFC),采用流体力学软件进行了DMFC三维阳极模型的模拟,利用MEMS加工技术和PDMS封装工艺实现了这种燃料电池,并在室温下对有效面积为8600μm× 8600μm的电池样品进行了性能测试.测试得到该DMFC的开路输出电压为0.5V,短路工作电流密度达到78.1mA/cm2,最大输出功率密度为3.86mW/cm2.主要参数已达到了一些电子器件的要求,具有一定的实用价值.     

硅基微型直接甲醇燃料电池的研究

设计了一种基于MEMS技术的硅基微型直接甲醇燃料电池（DMFC），采用流体力学软件进行了DMFC三维阳极模型的模拟，〖JP2〗利用MEMS加工技术和PDMS封装工艺实现了这种燃料电池，并在室温下对有效面积为8600μm×8600μm的电池样品进行了性能测试．测试得到该DMFC的开路输出电压为0.5V，短路工作电流密度达到78.1mA/cm2，最大输出功率密度为3.86mW/cm2．主要参数已达到了一些电子器件的要求，具有一定的实用价值．     

基于MEMS技术的微型燃料电池的制作

提出一套基于MEMS加工技术和薄膜淀积技术的硅基微型直接甲醇燃料电池的制作工艺流程。该微型燃料电池采用KOH体硅腐蚀技术得到流体通道,并溅射金属Pt层作为收集电流的电极。采用PDMS将两块带有微通道的燃料电池硅片与涂有催化剂层的质子交换膜密封粘合。制作得到的微型燃料电池单元的流道有效尺寸为:8 6mm×8 6mm。室温常压下,单电池的开路输出电压为0 4V左右。当输出电压为0 21V时,达到最大输出功率15 6μW(21 1μW/cm2)。     

直接甲醇燃料电池在通信基站的应用前景展望

直接甲醇燃料电池作为一种新型后备电源解决模式,其无污染、低噪音、温度范围广等特点日益受到各行业的重视。但直接甲醇燃料电池技术现在仍处于发展早期,国内各领域对其的研究都还很有限。本文通过对直接甲醇燃料电池本身的特性特点进行分析,并对其在通信基站的使用前景进行了展望。     

利用MEMS制作微型便携燃料电池

前言 便携式电子产品大多使用锂离子电池或是镍氢电池,不过目前锂离子电池的能量密度发展已经接近理论极限,比较之下燃料电池还有极大的能量密度发展空间,例如甲醇与相同体积锂离子电池蓄电量比较,甲醇拥有20倍左右的发热量,若以20%的电力转换效率,它可以产生数倍的电气能量,此外燃料电池不需要冗长的充电时间,而且对资源回收与削减电池使用量都具有正面贡献,因此微型燃料电池的发展受到全球重视.     

Flexible Solid-State Direct Ethanol Fuel Cell Catalyzed by Nanoporous High-Entropy Al-Pd-Ni-Cu-Mo Anode and Spinel (AlMnCo)3O4 Cathode

As in many other electrochemical energy-converting systems, the flexible direct ethanol fuel cells rely heavily on high-performance catalysts with low noble metal contents and high tolerance to poisoning. In this work, a generic dealloying procedure to synthesize nanoporous multicomponent anodic and cathodic catalysts for the high-performance ethanol fuel cells is reported. On the anode side, the nanoporous AlPdNiCuMo high-entropy alloy exhibits an electrochemically active surface area of 88.53 m² g⁻¹_Pd and a mass activity of 2.67 A mg⁻¹_Pd for the ethanol oxidation reaction. On the cathode side, the dealloyed spinel (AlMnCo)₃O₄ nanosheets with no noble metals demonstrate a comparable catalytic performance as the standard Pt/C for the oxygen reduction reaction, and tolerance to high concentrations of ethanol. Equipped with such anodic and cathodic catalysts, the flexible solid-state ethanol fuel cell is able to deliver an ultra-high energy density of 13.63 mWh cm⁻² with only 3 mL ethanol, which is outstanding compared with other similar solid-state energy devices. Moreover, the solid-state ethanol fuel cell is highly flexible, durable and exhibits an inject-and-run function.     

Strategy for Airflow Control of Cathode in Proton Exchange Membrane Fuel Cell

There are two important objectives for airflow control in proton exchange membrane fuel cells （PEMFCs）. One is to keep the desired excess ratio（to provide sufficient reactant airflow） to ensure fast transient response arid to minimize auxiliary power consumption, and the other one is to control the cathode pressure in stack within an acceptable range. In reality, the big inertia of stack＇s airflow-supplying activator limits the bandwidth of air-flow supply loop, which makes the first objective difficult to achieve, and another difficulty is that airflow is coupled with the cathode pressure in stack, which make it uneasy to keep the pressure unchanged in case of airflow perturbation. In order to overcome these difficulties, three dependant controllers are presented in this paper to control airflow, deeouple the cathode pressure in stack from airflow and stabilize the cat bode pressure in stack respectively. The effectiveness of these controllers is proven by subsequent simulation and test results.     

Direct 3D Printed Biomimetic Scaffolds Based on Hydrogel Microparticles for Cell Spheroid Growth

Biocompatible hydrogel inks with shear‐thinning, appropriate yield strength, and fast self‐healing are desired for 3D bioprinting. However, the lack of ideal 3D bioprinting inks with outstanding printability and high structural fidelity, as well as cell‐compatibility, has hindered the progress of extrusion‐based 3D bioprinting for tissue engineering. In this study, novel self‐healable pre‐cross‐linked hydrogel microparticles (pcHμPs) of chitosan methacrylate (CHMA) and polyvinyl alcohol (PVA) hybrid hydrogels are developed and used as bioinks for extrusion‐based 3D printing of scaffolds with high fidelity and biocompatibility. The pcHμPs display excellent shear thinning when injected through a syringe and subsequently self‐heal into gels as shear forces are removed. Numerical simulations indicate that the pcHμPs experience a plug flow in the nozzle with minimal disturbance, which favors a steady and continuous printing. Moreover, the pcHμPs show a self‐supportive yield strength (540 Pa), which is critical for the fidelity of printed constructs. A series of biomimetic constructs with very high aspect ratio and delicate fine structures are directly printed by using the pcHμP ink. The 3D printed scaffolds support the growth of bone‐marrow‐derived mesenchymal stem cells and formation of cell spheroids, which are most important for tissue engineering.     

A Tri-Port MIMO Antenna Designed for Micro/Pico Cell Applications with Self-Decoupled Structure

A tri-port MIMO antenna designed for Micro/Pico-Cell application is proposed. It is based on printed elements with X-shaped arms, which are oriented to 0°, 120° and 240° in the azimuth plane. The arms of these elements are connected, with which a selfdecoupled structure is formed. The mutual coupling between adjacent elements is below -15dB. Meanwhile, it size is compact and bidirectional radiation patterns with around 4dBi Gain and 92° 3dB beam width is achieved, which can provide good pattern diversity and full azimuth coverage in real applications.     

面向三维组装的微纳平台设计与研究

针对20~40μm尺寸范围的微对象夹持需求,设计了一种压电驱动的微组装夹持器平台。使用有限元分析优化了夹持器的结构参数。该平台可以实现两指与三指操作模式的转换及对多种微对象的柔性操作。该文绘制了实验平台中压电陶瓷的驱动电压与执行末端位移的关系,单指的驱动范围0~41μm。压电陶瓷对该平台的输出位移分辨率达到了0.5μm/V。以直径20μm、40μm两种尺寸的硼硅酸盐玻璃球为操作对象,完成了夹持、释放及三维模型组装实验。     

燃料电池发电系统结构与逆变控制研究

本文着眼于楼宇供电用燃料电池发电系统的研究，针对中等容量（几千瓦至几百千瓦）的功率变换装置，分析其运行特点和对系统结构和控制的基本要求，提出具体的系统方案与控制策略，满足楼宇供电燃料电池发电系统的并网发电和独立运行的要求。最后给出了一个5kVA的燃料电池发电装置试验结果。     

亚微米结构新型含钪扩散阴极性能的研究

本文研究具有氧化钪掺杂钨基体钪酸盐阴极的性能.为了改进氧化钪的分布均匀性及提高阴极表面钪的扩散补充能力,分别采用液固掺杂和液液掺杂的方法制备了Sc2O3掺杂W粉基材,研究了利用这种钨粉制作多孔钨基体的工艺技术和多孔体的微观结构.研究表明在改进压制、烧结技术的基础上,可以获得具有适当孔度的亚微米结构多孔基体,氧化钪在基体中的分布得到进一步改善,在这种基体中铝酸盐的浸渍率可以达到常规浸渍阴极的要求.发射试验结果表明,这种阴极在850 ℃的工作温度下空间电荷限制的电流密度超过30 A/cm2,在超过2000 h的寿命实验过程中发射仍持续上升,因而在要求高电流密度和一定寿命的微波电子管中具有光明的应用前景.研究还证实多孔体的结构越趋细微,越有利于阴极的发射均匀性和耐离子轰击的性能改善.     

An Electrolyte‐Free Fuel Cell Constructed from One Homogenous Layer with Mixed Conductivity

Rather than using three layers, including an electrolyte, a working fuel cell is created that employs only one homogenous layer with mixed conductivity. The layer is a composite made from a mixture of metal oxide, Li_0.15Ni_0.45Zn_0.4 oxide, and an ionic conductor; ion‐doped ceria. The single‐component layer has a total conductivity of 0.1–1 S cm^?1 and exhibits both ionic and semiconducting properties. This homogenous one‐layer device has a power output of more than 600 mW cm^?2 at 550 °C operating with H₂ and air. Overall conversion is completed in a similar way to a traditional fuel cell, even though the device does not include the electrolyte layer critical for traditional fuel‐cell technologies using the three‐component anode–electrolyte–cathode structure.     

Direct Ink Writing of 3D Functional Materials

The ability to pattern materials in three dimensions is critical for several technological applications, including composites, microfluidics, photonics, and tissue engineering. Direct‐write assembly allows one to design and rapidly fabricate materials in complex 3D shapes without the need for expensive tooling, dies, or lithographic masks. Here, recent advances in direct ink writing are reviewed with an emphasis on the push towards finer feature sizes. Opportunities and challenges associated with direct ink writing are also highlighted.     

An In Situ Formed,Dual‐Phase Cathode with a Highly Active Catalyst Coating for Protonic Ceramic Fuel Cells

Composite cathodes of solid oxide fuel cells (SOFCs) are normally fabricated by mechanical mixing of electronic‐ and ionic‐conducting phases. Here, a dual‐phase SOFC cathode, composed of perovskite PrNi_0.5Mn_0.5O₃ (PNM) and exsoluted fluorite PrO_x particles, produced in situ through a glycine–nitrate solution combustion process, is reported. When applied as the cathode for a BaZr_0.1Ce_0.7Y_0.1Yb_0.1O₃‐based protonic ceramic fuel cell, the hybrid cathode displays excellent electrocatalytic activity (area‐specific resistance of 0.052 Ω cm² at 700 °C) and remarkable long‐term stability when operated at a cell voltage of 0.7 V for ≈500 h using H₂ as fuel and ambient air as oxidant. The excellent performance is attributed to the proton‐conducting BaPrO₃‐based coating and high‐concentration oxygen vacancies of a Ba‐doped PNM surface coating, produced by the reaction between the cathode and Ba from the electrolyte (via evaporation or diffusion), as confirmed by detailed X‐ray photoelectron spectroscopy, Raman spectroscopy, and density functional theory‐based calculations.     

基于深度相机的小型无人机室内三维地图构建

为了解决小型无人机在室内光线不足情况下的避障以及路径规划问题,设计了一种基于深度相机的无人机室内地图构建系统。文中使用Pixhawk控制板和低成本嵌入式结构光深度相机硬件平台,为避障以及路径规划目标提供室内环境信息。采用反传感器模型算法,利用深度相机和位姿传感器提供的信息来筛选处理出有效的障碍物信息,并构建室内的三维地图,其中深度相机通过激光扫描的方式来获取障碍物点云的描述信息,利用位姿传感器获取无人机的高度信息。实验结果表明,使用该系统能够快速获取室内地图,对障碍物的判断准确率比较高,且不受光线影响,可以广泛应用于无人机的室内导航,实现不依赖外部光源的室内无人机地图构建系统。     

基于OpenGL与Direct3D的室内软装三维模拟系统设计

针对传统室内软装三维模拟系统选取几何建模方法三维模拟室内软装效果,缺乏有效的充实和渲染手段,真实性差。文中设计一种基于OpenGL与Direct3D的室内软装三维模拟系统,采用3DMAX软件建立室内模型,将该模型导入OpenGL三维图形标准库模块中,利用基本几何图元绘制室内软装场景元素,通过穿墙、重叠以及尺寸约束函数对场景元素进行约束,确保室内软装代理区域合理布局,充实室内模型,充实后室内模型传送至Direct3D渲染引擎模块变换单元实施软装布局,利用照明单元和光栅化单元对布局后室内进行渲染,获取最优室内软装效果,并输出室内软装三维模拟图像。实验结果表明,利用该系统三维模拟的室内软装真实性强,编辑操作平均运行时间为327 ms,用户满意度高。     

Highly Efficient 1D/3D Ferroelectric Perovskite Solar Cell

With the capability to manipulate the built-in field in solar cells, ferroelectricity is found to be a promising attribute for harvesting solar energy in solar cell devices by influencing associated device parameters. Researchers have devoted themselves to the exploration of ferroelectric materials that simultaneously possess strong light absorption and good electric transport properties for a long time. Here, it is presented a novel and facile approach of combining state-of-art light absorption and electric transport properties with ferroelectricity by the incorporation of room temperature 1D ferroelectric perovskite with 3D organic–inorganic hybrid perovskite (OIHP). The 1D/3D mixed OIHP films are found to exhibit evident ferroelectric properties. It is notable that the poling of the 1D/3D mixed ferroelectric OIHP solar cell can increase the average V_oc can be increased from 1.13 to 1.16 V, the average PCE from 20.7% to 21.5%. A maximum power conversion efficiency of 22.7%, along with an enhanced fill factor of over 80% and open-circuit voltage of 1.19 V, can be achieved in the champion device. The enhancement is by virtue of reduced surface recombination by ferroelectricity-induced modification of the built-in field. The maximum power point tracking measurement substantiates the retention of ferroelectric-polarization during the continued operation.     

Direct Freeform Laser Fabrication of 3D Conformable Electronics

3D conformable electronic devices on freeform surfaces show superior performance to the conventional, planar ones. They represent a trend of future electronics and have witnessed exponential growth in various applications. However, their potential is largely limited by a lack of sophisticated fabrication techniques. To tackle this challenge, a new direct freeform laser (DFL) fabrication method enabled by a 5-axis laser processing platform for directly fabricating 3D conformable electronics on targeted arbitrary surfaces is reported. Accordingly, representative laser-induced graphene (LIG), metals, and metal oxides are successfully fabricated as high-performance sensing and electrode materials from different material precursors on various types of substrates for applications in temperature/light/gas sensing, energy storage, and printed circuit board for circuit. Last but not the least, to demonstrate an application in smart homes, LIG-based conformable strain sensors are fabricated and distributed in designated locations of an artificial tree. The distributed sensors have the capability of monitoring the wind speed and direction with the assistance of well-trained machine-learning models. This novel process will pave a new and general route to fabricating 3D conformable electronic devices, thus creating new opportunities in robotics, biomedical sensing, structural health, environmental monitoring, and Internet of Things applications.