{"defaultlang":"zh","titlegroup":{"articletitle":[{"lang":"zh","data":[{"name":"text","data":"无线控制式原子力显微镜系统"}]},{"lang":"en","data":[{"name":"text","data":"Development of wirelessly controlled atomic force microscope"}]}]},"contribgroup":{"author":[{"name":[{"lang":"zh","surname":"章","givenname":"海军","namestyle":"eastern","prefix":""},{"lang":"en","surname":"ZHANG","givenname":"Hai-jun","namestyle":"western","prefix":""}],"stringName":[],"aff":[{"rid":"aff1","text":""}],"role":["corresp","first-author"],"corresp":[{"rid":"cor1","lang":"en","text":"ZHANG Hai-jun, E-mail:zhanghj@zju.edu.cn","data":[{"name":"text","data":"ZHANG Hai-jun, E-mail:zhanghj@zju.edu.cn"}]}],"bio":[{"lang":"zh","text":["章海军(1965-), 男, 浙江新昌人, 教授, 博士生导师, 1993年于浙江大学获得博士学位, 主要从事光学工程及原子力显微镜技术的研究。E-mail:zhanghj@zju.edu.cn"],"graphic":[],"data":[[{"name":"bold","data":[{"name":"text","data":"章海军"}]},{"name":"text","data":"(1965-), 男, 浙江新昌人, 教授, 博士生导师, 1993年于浙江大学获得博士学位, 主要从事光学工程及原子力显微镜技术的研究。E-mail:"},{"name":"text","data":"zhanghj@zju.edu.cn"}]]}],"email":"zhanghj@zju.edu.cn","deceased":false},{"name":[{"lang":"zh","surname":"陈","givenname":"佳骏","namestyle":"eastern","prefix":""},{"lang":"en","surname":"CHEN","givenname":"Jia-jun","namestyle":"western","prefix":""}],"stringName":[],"aff":[{"rid":"aff1","text":""}],"role":[],"bio":[{"lang":"zh","text":["陈佳骏(1994-), 男, 浙江东阳人, 硕士研究生, 2016年于浙江大学获得学士学位, 主要从事原子力显微镜技术及系统的研究。E-mail:21630060@zju.edu.cn"],"graphic":[],"data":[[{"name":"bold","data":[{"name":"text","data":"陈佳骏"}]},{"name":"text","data":"(1994-), 男, 浙江东阳人, 硕士研究生, 2016年于浙江大学获得学士学位, 主要从事原子力显微镜技术及系统的研究。E-mail:"},{"name":"text","data":"21630060@zju.edu.cn"}]]}],"email":"21630060@zju.edu.cn","deceased":false},{"name":[{"lang":"zh","surname":"王","givenname":"英达","namestyle":"eastern","prefix":""},{"lang":"en","surname":"WANG","givenname":"Ying-da","namestyle":"western","prefix":""}],"stringName":[],"aff":[{"rid":"aff1","text":""}],"role":[],"deceased":false},{"name":[{"lang":"zh","surname":"尤","givenname":"清扬","namestyle":"eastern","prefix":""},{"lang":"en","surname":"YOU","givenname":"Qing-yang","namestyle":"western","prefix":""}],"stringName":[],"aff":[{"rid":"aff1","text":""}],"role":[],"deceased":false}],"aff":[{"id":"aff1","intro":[{"lang":"zh","label":"","text":"浙江大学 光电科学与工程学院 现代光学仪器国家重点实验室, 浙江 杭州 310027","data":[{"name":"text","data":"浙江大学 光电科学与工程学院 现代光学仪器国家重点实验室, 浙江 杭州 310027"}]},{"lang":"en","label":"","text":"State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, China","data":[{"name":"text","data":"State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, China"}]}]}]},"abstracts":[{"lang":"zh","data":[{"name":"p","data":[{"name":"text","data":"提出了一种基于嵌入式系统和WiFi无线控制的接触模式原子力显微镜（AFM）系统。该AFM系统直接由迷你型移动电源给扫描与反馈电路及嵌入式系统等供电；嵌入式系统由微型电脑树莓派和微小型AD "},{"name":"text","data":"&"},{"name":"text","data":" DA模块构成，通过WiFi与笔记本电脑实现无线数据通信。利用这一方法，成功研发了无线控制式AFM系统，并开展了微纳米样品的扫描成像实验。实验结果表明，该AFM系统的横向分辨率达到纳米量级，纵向分辨率达到0.1 nm，最大扫描范围为3.6 "},{"name":"italic","data":[{"name":"text","data":"μ"}]},{"name":"text","data":"m×3.6 "},{"name":"italic","data":[{"name":"text","data":"μ"}]},{"name":"text","data":"m。该系统的显著特点是无需交流市电供电，无需直流高压电源，也无需与计算机之间的线缆连接，可在约100 m远处通过无线控制的方式实现AFM的扫描成像。这一新型AFM系统，不仅能够在微纳米技术的常规领域得到应用，而且在野外考察、隔离环境、真空条件、气体氛围环境及星际探测等特殊领域具有广阔的应用前景。"}]}]},{"lang":"en","data":[{"name":"p","data":[{"name":"text","data":"This paper proposes a contact mode Atomic Force Microscope (AFM) based on an embedded system and WiFi control. This AFM utilizes a portable power supply to drive the scanning/feedback circuit and an embedded system. The embedded system, which consists of a micro-computer (Raspberry Pi) and a micro AD & DA module, realizes WiFi-based communication with a laptop computer. Using this approach, a wirelessly controlled AFM is developed and experiments are performed using different samples. The results indicate that the horizontal resolution of the AFM is in nanometer order, and vertical resolution is 0.1 nm. Furthermore, the AFM can achieve a maximum scan range of 3.6 m×3.6 m. The advantages of the proposed setup include the circumvention of the need for commercial and high-voltage DC power supplies, and the obviation of a cable connection between the embedded system and the laptop computer. The system is capable of realizing AFM scanning and imaging via wireless control at approximately 100 m away. This AFM can be potentially applied in most micro/nano-technology fields. Moreover, it allows for special applications in outdoor investigations, isolated spaces, vacuum conditions, gas environments, and even interstellar exploration."}]}]}],"keyword":[{"lang":"zh","data":[[{"name":"text","data":"原子力显微镜"}],[{"name":"text","data":"嵌入式系统"}],[{"name":"text","data":"WiFi"}],[{"name":"text","data":"无线控制"}],[{"name":"text","data":"移动电源"}]]},{"lang":"en","data":[[{"name":"text","data":"Atomic Force Microscope(AFM)"}],[{"name":"text","data":"embedded system"}],[{"name":"text","data":"WiFi"}],[{"name":"text","data":"wirelessly controlled"}],[{"name":"text","data":"portable power supply"}]]}],"highlights":[],"body":[{"name":"sec","data":[{"name":"sectitle","data":{"label":[{"name":"text","data":"1"}],"title":[{"name":"text","data":"引言"}],"level":"1","id":"s1"}},{"name":"p","data":[{"name":"text","data":"近年来，微纳米技术的研究及应用得到了飞速发展"},{"name":"sup","data":[{"name":"text","data":"["},{"name":"blockXref","data":{"data":[{"name":"xref","data":{"text":"1","type":"bibr","rid":"b1","data":[{"name":"text","data":"1"}]}},{"name":"text","data":"-"},{"name":"xref","data":{"text":"4","type":"bibr","rid":"b4","data":[{"name":"text","data":"4"}]}}],"rid":["b1","b2","b3","b4"],"text":"1-4","type":"bibr"}},{"name":"text","data":"]"}]},{"name":"text","data":"。以扫描隧道显微镜(Scanning Tunneling Microscope，STM)和原子力显微镜(Atomic Force Microscope，AFM)为主要代表的扫描探针显微镜(Scanning Probe Microscope，SPM)，是微纳米技术发展的重要基础。由于AFM既具有很高的扫描成像分辨率，又不受微纳米样品的导电性和物质态的限制"},{"name":"sup","data":[{"name":"text","data":"["},{"name":"xref","data":{"text":"5","type":"bibr","rid":"b5","data":[{"name":"text","data":"5"}]}},{"name":"text","data":"]"}]},{"name":"text","data":"，因此其应用更为广泛，是微纳米技术及其分支学科中不可或缺的重要工具"},{"name":"sup","data":[{"name":"text","data":"["},{"name":"blockXref","data":{"data":[{"name":"xref","data":{"text":"6","type":"bibr","rid":"b6","data":[{"name":"text","data":"6"}]}},{"name":"text","data":"-"},{"name":"xref","data":{"text":"8","type":"bibr","rid":"b8","data":[{"name":"text","data":"8"}]}}],"rid":["b6","b7","b8"],"text":"6-8","type":"bibr"}},{"name":"text","data":"]"}]},{"name":"text","data":"。"}]},{"name":"p","data":[{"name":"text","data":"自AFM诞生以来，国内外有关AFM技术的研究得到了长足的发展，AFM性能也逐步完善"},{"name":"sup","data":[{"name":"text","data":"["},{"name":"xref","data":{"text":"9","type":"bibr","rid":"b9","data":[{"name":"text","data":"9"}]}},{"name":"text","data":"]"}]},{"name":"text","data":"。但是，现有的AFM系统在某些方面存在着明显的局限性，例如，需要交流市电供电及专门的直流低压与高压电源，控制系统较为复杂和庞大；需要有PCI插槽或USB接口的AD"},{"name":"text","data":"&"},{"name":"text","data":"DA控制卡"},{"name":"sup","data":[{"name":"text","data":"["},{"name":"blockXref","data":{"data":[{"name":"xref","data":{"text":"10","type":"bibr","rid":"b10","data":[{"name":"text","data":"10"}]}},{"name":"text","data":"-"},{"name":"xref","data":{"text":"11","type":"bibr","rid":"b11","data":[{"name":"text","data":"11"}]}}],"rid":["b10","b11"],"text":"10-11","type":"bibr"}},{"name":"text","data":"]"}]},{"name":"text","data":"，与PC机或一体机之间需要通过线缆连接，从而限制了AFM在野外考察、隔离环境、真空条件、气体氛围环境及星际探测等特殊领域的应用"},{"name":"sup","data":[{"name":"text","data":"["},{"name":"blockXref","data":{"data":[{"name":"xref","data":{"text":"12","type":"bibr","rid":"b12","data":[{"name":"text","data":"12"}]}},{"name":"text","data":"-"},{"name":"xref","data":{"text":"14","type":"bibr","rid":"b14","data":[{"name":"text","data":"14"}]}}],"rid":["b12","b13","b14"],"text":"12-14","type":"bibr"}},{"name":"text","data":"]"}]},{"name":"text","data":"。"}]},{"name":"p","data":[{"name":"text","data":"本文研究发展了一种基于嵌入式系统与WiFi的无线控制式AFM技术，其显著特点包括：由移动电源替代交流市电直接供电；无需直流稳压电源及高压电源；控制电路系统实现了微小型化；也无需PCI插槽或USB接口的AD & DA模块与计算机之间进行导线连接，直接以WiFi远程控制的方式实现AFM的扫描控制及成像，克服了常规AFM的局限性，可望在微纳米技术及特殊领域获得广泛应用。"}]}]},{"name":"sec","data":[{"name":"sectitle","data":{"label":[{"name":"text","data":"2"}],"title":[{"name":"text","data":"原理与方法"}],"level":"1","id":"s2"}},{"name":"p","data":[{"name":"xref","data":{"text":"图 1","type":"fig","rid":"Figure1","data":[{"name":"text","data":"图 1"}]}},{"name":"text","data":"所示为基于嵌入式系统的无线控制式AFM系统框图。该系统主要包括AFM探头、扫描与反馈电路、嵌入式系统、计算机(如笔记本电脑)等部分。AFM探头由微探针(Tip)、光电检测模块、样品(Sa)及样品台、压电陶瓷扫描与反馈控制器(Sc)、微调机构及基座等部分组成。其中，光电检测模块包括半导体激光器(LD)、位置敏感探测器(PSD)等部分，采用光束偏转法实现微探针(微悬臂)偏转量的检测。扫描与反馈电路由比例-微分-积分反馈控制模块(PID)、扫描控制电路("},{"name":"italic","data":[{"name":"text","data":"XY"}]},{"name":"text","data":")、移动电源(PPS)及升压片等组成。由微型电脑树莓派(RP)及微小型AD "},{"name":"text","data":"&"},{"name":"text","data":" DA模块构成的嵌入式系统，以WiFi无线控制的方式与笔记本电脑之间实现数据通信；由扫描与反馈电路实现样品的 "},{"name":"italic","data":[{"name":"text","data":"XY"}]},{"name":"text","data":"扫描和"},{"name":"italic","data":[{"name":"text","data":"Z"}]},{"name":"text","data":"向信息的读取，进而实现微纳米成像。"}]},{"name":"fig","data":{"id":"Figure1","caption":[{"lang":"zh","label":[{"name":"text","data":"图1"}],"title":[{"name":"text","data":"基于嵌入式系统及WiFi的无线控制式AFM系统框图"}]},{"lang":"en","label":[{"name":"text","data":"Fig 1"}],"title":[{"name":"text","data":"Schematic diagram of embedded system and WiFi-based wirelessly controlled AFM"}]}],"subcaption":[],"note":[],"graphics":[{"print":"http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=1709678&type=","small":"http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=1709678&type=small","big":"http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=1709678&type=middle"}]}},{"name":"p","data":[{"name":"text","data":"无线控制式AFM系统的基本原理与常规AFM相同，即基于探针-样品之间的原子力作用机制，在此不进行详述。与常规AFM显著不同的是，本文的AFM采用WiFi无线传输的方式实现样品的扫描成像。其中的AD采样模块为24位，采样速率为30 kHz；DA模块为16位，采样速率可达1 MHz；笔记本电脑与嵌入式系统之间的实测WiFi平均传输速率为2.5 MHz，因此，图像扫描及数据传输的瓶颈主要出现在AD采样方面。当每幅AFM图像的扫描像素设定为400×400 pixel(即16万像素)时，以30 kHz的AD采样速率，最高可实现1幅图像/5.4 s的扫描速度。在实验中，通过延时设置将每幅图像的扫描时间调至20 s以上，以保证图像的扫描质量。由笔记本电脑发出的扫描指令，以无线控制的方式开启嵌入式系统的扫描程序，使微探针相对于样品进行"},{"name":"italic","data":[{"name":"text","data":"XY"}]},{"name":"text","data":"扫描，即可获得样品表面的三维形貌图像，最终在笔记本电脑上显示和存储。"}]}]},{"name":"sec","data":[{"name":"sectitle","data":{"label":[{"name":"text","data":"3"}],"title":[{"name":"text","data":"系统研制"}],"level":"1","id":"s3"}},{"name":"sec","data":[{"name":"sectitle","data":{"label":[{"name":"text","data":"3.1"}],"title":[{"name":"text","data":"AFM探头设计"}],"level":"2","id":"s3-1"}},{"name":"p","data":[{"name":"xref","data":{"text":"图 1","type":"fig","rid":"Figure1","data":[{"name":"text","data":"图 1"}]}},{"name":"text","data":"所示的无线控制式AFM系统采用的是样品扫描方式，即在扫描过程中保持微探针的位置不变，以样品扫描和反馈的方式实现微纳米扫描成像。扫描与反馈控制器由三个相互正交的小压电陶瓷条(长1.6 mm×宽1.6 mm×高10 mm)构成，分别控制施加在陶瓷条正负电极上的驱动电压，实现样品的"},{"name":"italic","data":[{"name":"text","data":"XY"}]},{"name":"text","data":"扫描和"},{"name":"italic","data":[{"name":"text","data":"Z"}]},{"name":"text","data":"向反馈，样品的最大尺寸约为10 mm×10 mm×5 mm。与需要高压(如200~300 V)驱动的传统管状压电陶瓷相比，该压电陶瓷条在几十伏(如42 V)的直流电压控制下即可获得微米量级(如3.6 "},{"name":"italic","data":[{"name":"text","data":"μ"}]},{"name":"text","data":"m)的扫描与反馈控制量。另一方面，AFM控制软件中设定的最小扫描范围为300 nm×300 nm，图像像素为400×400 pixel，此时DA输出的控制电压步长为8.75 mV，对应于最小控制步长约为0.75 nm，即小于1 nm。而几十伏的扫描电压(电压差)，可在移动电源及升压片的供电下，由嵌入式系统控制的扫描与反馈电路提供和实现。为了减少和消除振动影响，AFM探头中的所有部件，都以同一块厚底板作为基础；竖立的安装板，采用两条斜加强筋进一步固定和强化；激光器、微探针和PSD元件等，都安装在同一调节机构上，以保持三者的相对位置不变及光路的稳定；AFM探头底板下方安装了三个橡皮垫圈作为支脚，实验过程中将AFM探头放置在一个小沙箱上，以隔绝桌面或地面的震动。"}]},{"name":"p","data":[{"name":"text","data":"该AFM系统采用的是PNP-TR型微探针，其V字形微悬臂的有效长度分为100 "},{"name":"italic","data":[{"name":"text","data":"μ"}]},{"name":"text","data":"m和200 "},{"name":"italic","data":[{"name":"text","data":"μ"}]},{"name":"text","data":"m两种，弹性系数分别为0.32 N/m和0.08 N/m。选取波长为650 nm、功率为4 mW的半导体激光器作为光源，光电接收器选用本单位自行研制的P233型二维PSD，其最高位置分辨率可达0.5 "},{"name":"italic","data":[{"name":"text","data":"μ"}]},{"name":"text","data":"m，当光杠杆比为2 000倍时，可获得0.25 nm的纵向分辨率。"}]}]},{"name":"sec","data":[{"name":"sectitle","data":{"label":[{"name":"text","data":"3.2"}],"title":[{"name":"text","data":"扫描与反馈电路研制"}],"level":"2","id":"s3-2"}},{"name":"p","data":[{"name":"text","data":"为了实现扫描与反馈控制器的微米级位移控制，常规AFM的控制电路一般需要输出200~300 V的直流高压驱动信号，因此必须依赖于交流市电供电及专用的高压直流电源。为了克服这一局限性，本文的AFM系统的扫描与反馈电路直接采用两个迷你型移动电源供电，每个电源仅需1节18650电池，直径为1.8 cm，长度为6.5 cm。移动电源的输出电压在5 V左右，因此由其中的一个电源给嵌入式系统直接供电；同时，采用两个升压片再将两个电源的电压均升压到22 V，并将升压后的一个负输出端与另一个正输出端相连接，作为接地端，由此构成±22 V的双极性电源，给扫描与反馈电路供电。实验表明，给微型电脑树莓派和AD & DA模块供电的单个迷你型移动电源可连续开机工作6 h以上；给扫描与反馈电路供电的两个迷你型移动电源，可连续工作9 h以上。由于电池直接提供直流电压，而不是间接地从交流市电整流和滤波获得直流电压，因此不存在纹波干扰等噪声。"}]},{"name":"p","data":[{"name":"text","data":"扫描与反馈电路的总体框图如"},{"name":"xref","data":{"text":"图 2","type":"fig","rid":"Figure2","data":[{"name":"text","data":"图 2"}]}},{"name":"text","data":"所示。由树莓派发出的扫描控制电压信号(以"},{"name":"italic","data":[{"name":"text","data":"X"}]},{"name":"text","data":"方向的电压信号为例)，通过微小型DA接口输出，经电压跟随器("},{"name":"italic","data":[{"name":"text","data":"X"}]},{"name":"text","data":"跟随)和电压放大电路("},{"name":"italic","data":[{"name":"text","data":"X"}]},{"name":"text","data":"放大)后，再分别进行正相放大("},{"name":"italic","data":[{"name":"text","data":"V"}]},{"name":"sub","data":[{"name":"italic","data":[{"name":"text","data":"X"}]},{"name":"text","data":"+"}]},{"name":"text","data":")和反相放大("},{"name":"italic","data":[{"name":"text","data":"V"}]},{"name":"sub","data":[{"name":"italic","data":[{"name":"text","data":"X"}]},{"name":"text","data":"-"}]},{"name":"text","data":")后，施加到"},{"name":"italic","data":[{"name":"text","data":"X"}]},{"name":"text","data":"向压电陶瓷条(PZT"},{"name":"sub","data":[{"name":"italic","data":[{"name":"text","data":"X"}]}]},{"name":"text","data":")的正负极上，实现"},{"name":"italic","data":[{"name":"text","data":"X"}]},{"name":"text","data":"方向的扫描；"},{"name":"italic","data":[{"name":"text","data":"Y"}]},{"name":"text","data":"方向的扫描控制电路与"},{"name":"italic","data":[{"name":"text","data":"X"}]},{"name":"text","data":"方向类似。另一方面，从PSD输出的光电流信号("},{"name":"italic","data":[{"name":"text","data":"I"}]},{"name":"sub","data":[{"name":"text","data":"PSD"}]},{"name":"text","data":"，与原子力或微探针-样品间距相对应)，经前置放大器("},{"name":"italic","data":[{"name":"text","data":"I"}]},{"name":"text","data":"/"},{"name":"italic","data":[{"name":"text","data":"V"}]},{"name":"text","data":")转换成电压信号后，一路通过微小型AD接口输入树莓派，另一路输入到反馈控制模块(PID)，获得反馈控制电压信号；再分别进行正相放大("},{"name":"italic","data":[{"name":"text","data":"V"}]},{"name":"sub","data":[{"name":"italic","data":[{"name":"text","data":"Z"}]},{"name":"text","data":"+"}]},{"name":"text","data":")和反相放大("},{"name":"italic","data":[{"name":"text","data":"V"}]},{"name":"sub","data":[{"name":"italic","data":[{"name":"text","data":"Z"}]},{"name":"text","data":"-"}]},{"name":"text","data":")后，施加到"},{"name":"italic","data":[{"name":"text","data":"Z"}]},{"name":"text","data":"向压电陶瓷条(PZT"},{"name":"sub","data":[{"name":"italic","data":[{"name":"text","data":"Z"}]}]},{"name":"text","data":")的正负极上，带动样品进行"},{"name":"italic","data":[{"name":"text","data":"Z"}]},{"name":"text","data":"向运动，从而实现微探针-样品间距的"},{"name":"italic","data":[{"name":"text","data":"Z"}]},{"name":"text","data":"向反馈控制。扫描与反馈电路输出的最大正相与反相电压可分别达到+21 V与-21 V，即压电陶瓷条上的最大控制电压差可达42 V，据此完全能够实现微米量级的扫描与反馈控制。"}]},{"name":"fig","data":{"id":"Figure2","caption":[{"lang":"zh","label":[{"name":"text","data":"图2"}],"title":[{"name":"text","data":"扫描与反馈电路框图"}]},{"lang":"en","label":[{"name":"text","data":"Fig 2"}],"title":[{"name":"text","data":"Scheme of scanning and feedback control circuit"}]}],"subcaption":[],"note":[],"graphics":[{"print":"http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=1709696&type=","small":"http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=1709696&type=small","big":"http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=1709696&type=middle"}]}},{"name":"p","data":[{"name":"text","data":"PID反馈控制模块可提供两种扫描成像模式，即等高模式和恒力模式。在反馈控制模块中，RC积分器的积分电容为1 "},{"name":"italic","data":[{"name":"text","data":"μ"}]},{"name":"text","data":"F，电阻在100 Ω~100 kΩ之间可调。当电阻调节至100 kΩ时，积分时间常数为0.1 s(10 Hz)，而图像扫描速度为16万像素/45 s(约3 500 Hz)，因此反馈速度远低于扫描速度，等效于关闭反馈，扫描模式为等高模式。此时，从AD接口读取与PSD电流信号对应的电压信号，作为样品图像的高度信息。当电阻调节至100 Ω左右时，积分时间常数为0.1 ms(10 kHz)，反馈灵敏度足以支持扫描成像的速度，对应于恒力模式。在扫描过程中，"},{"name":"italic","data":[{"name":"text","data":"Z"}]},{"name":"text","data":"向压电陶瓷条带动样品不断在"},{"name":"italic","data":[{"name":"text","data":"Z"}]},{"name":"text","data":"向进行反馈运动，运动量与样品表面的起伏相对应。通过AD接口读取PID反馈电路施加在"},{"name":"italic","data":[{"name":"text","data":"Z"}]},{"name":"text","data":"向压电陶瓷条上的反馈电压信息(经电位器分压后再读取)，同样可获得样品表面的三维形貌。"}]}]},{"name":"sec","data":[{"name":"sectitle","data":{"label":[{"name":"text","data":"3.3"}],"title":[{"name":"text","data":"嵌入式系统及无线控制软硬件"}],"level":"2","id":"s3-3"}},{"name":"p","data":[{"name":"text","data":"如上文所述，嵌入式系统由微型电脑树莓派和微小型AD & DA模块组成，两者的尺寸分别为8.6 cm×5.6 cm和6.5 cm×5.6 cm。该系统作为AFM的主控模块，实现AFM的扫描控制、信号采集、数据存储、图像显示及处理等功能。"}]},{"name":"p","data":[{"name":"text","data":"为了实现无线通信，笔记本电脑通过无线网卡接收WiFi信号，树莓派通过集成发射模块(博通BCM43438)发射WiFi信号，由此实现无需局域网的无线互联。之后，笔记本电脑通过远程操作软件VNC实现嵌入式系统的图形化界面操作，软件由客户端应用程序VNC Viewer和服务器应用程序VNC Server两部分组成，实现笔记本电脑与树莓派之间的交互访问及AFM系统的扫描成像。如需要进行远程(如A市与B市之间)的扫描控制与成像，可以将位于A市的AFM系统(含微型电脑树莓派等)和位于B市的笔记本电脑分别接入当地的局域网，即可实现远程扫描控制与成像。"}]}]}]},{"name":"sec","data":[{"name":"sectitle","data":{"label":[{"name":"text","data":"4"}],"title":[{"name":"text","data":"实验及结果"}],"level":"1","id":"s4"}},{"name":"p","data":[{"name":"text","data":"利用研制完成的基于WiFi的无线控制式AFM系统，开展了微纳米样品的扫描成像实验，以考察该系统的性能。实验在室外(校园)进行，AFM探头及控制系统(集扫描与反馈电路和嵌入式系统于一体)放置于校园内的一处石阶上；而作为总体控制的笔记本电脑，置于约100 m远处的石凳上。嵌入式系统在开启移动电源后，与笔记本电脑之间通过WiFi建立远程数据通信，进而控制AFM的扫描成像。AFM在工作时需要先将探针逐步逼近样品并选取工作点，本文的样机系统主要侧重于实现AFM扫描成像的无线控制，同时省去交流市电电源，因此，实验中采用手动粗调和微调的方式实现探针与样品之间的逼近。今后，将进一步以遥控方式实现探针与样品之间的自动逼近。"}]},{"name":"p","data":[{"name":"text","data":"首先以多孔氧化铝(Porous Alumina，PA)作为样品，在AFM系统开机1 min和10 min后分别进行扫描成像，获得的结果如"},{"name":"xref","data":{"text":"图 3","type":"fig","rid":"Figure3","data":[{"name":"text","data":"图 3"}]}},{"name":"text","data":"所示。采用的扫描模式为等高模式，图像扫描范围为600 nm×600 nm，像素为400×400 pixel，每幅图像的扫描时间约为22 s。从图中可以看到，PA纳米孔的平均直径约为48 nm，平均孔中心距约为95 nm。"},{"name":"xref","data":{"text":"图 3(a)","type":"fig","rid":"Figure3","data":[{"name":"text","data":"图 3(a)"}]}},{"name":"text","data":"和"},{"name":"xref","data":{"text":"图 3(b)","type":"fig","rid":"Figure3","data":[{"name":"text","data":"图 3(b)"}]}},{"name":"text","data":"中箭头所指的是同一位置，两者之间存在少许平移，这主要是由于AFM系统开机后需要有一定的时间消除热漂移，最终才能使其性能稳定下来。尽管如此，扫描图像表明：该AFM系统具有纳米级的横向分辨率和0.1 nm量级的纵向分辨率，并具有良好的图像对比度和重复性。"}]},{"name":"fig","data":{"id":"Figure3","caption":[{"lang":"zh","label":[{"name":"text","data":"图3"}],"title":[{"name":"text","data":"多孔氧化铝纳米结构的AFM图像"}]},{"lang":"en","label":[{"name":"text","data":"Fig 3"}],"title":[{"name":"text","data":"AFM images of porous alumina"}]}],"subcaption":[],"note":[],"graphics":[{"print":"http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=1709717&type=","small":"http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=1709717&type=small","big":"http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=1709717&type=middle"}]}},{"name":"p","data":[{"name":"text","data":"选取具有周期性纳米压印结构的样品，进一步开展了较大范围的AFM扫描成像实验，如"},{"name":"xref","data":{"text":"图 4","type":"fig","rid":"Figure4","data":[{"name":"text","data":"图 4"}]}},{"name":"text","data":"所示。采用的扫描模式为等高模式，图像扫描范围为3.6"},{"name":"italic","data":[{"name":"text","data":"μ"}]},{"name":"text","data":"m×3.6 "},{"name":"italic","data":[{"name":"text","data":"μ"}]},{"name":"text","data":"m，像素为400×400 pixel，每幅图像的扫描时间约为45 s。结果显示，纳米压印结构的平均边长约为260 nm，最大高度分别为167.6和165.9 nm。"},{"name":"xref","data":{"text":"图 4(a)","type":"fig","rid":"Figure4","data":[{"name":"text","data":"图 4(a)"}]}},{"name":"text","data":"和"},{"name":"xref","data":{"text":"图 4(b)","type":"fig","rid":"Figure4","data":[{"name":"text","data":"图 4(b)"}]}},{"name":"text","data":"中箭头所指的是同一纳米压印结构，两者之间存在少许平移，同样是因为AFM系统开机后需要一定的时间来消除热漂移。两幅图像具有很好的重复性和对比度；同时，在纳米压印阵列结构之间，还可以看到在基底上分布有许多更细小的纳米颗粒，进一步说明该AFM系统具有很高的分辨率。"}]},{"name":"fig","data":{"id":"Figure4","caption":[{"lang":"zh","label":[{"name":"text","data":"图4"}],"title":[{"name":"text","data":"纳米压印阵列结构的AFM图像"}]},{"lang":"en","label":[{"name":"text","data":"Fig 4"}],"title":[{"name":"text","data":"AFM images of nano-imprint structures"}]}],"subcaption":[],"note":[],"graphics":[{"print":"http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=1709738&type=","small":"http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=1709738&type=small","big":"http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=1709738&type=middle"}]}},{"name":"p","data":[{"name":"text","data":"为了进一步评价PID控制系统的性能，以恒力模式对纳米压印结构样品进行了扫描成像，结果如"},{"name":"xref","data":{"text":"图 5","type":"fig","rid":"Figure5","data":[{"name":"text","data":"图 5"}]}},{"name":"text","data":"所示。图像扫描范围为3.6 "},{"name":"italic","data":[{"name":"text","data":"μ"}]},{"name":"text","data":"m×3.6 "},{"name":"italic","data":[{"name":"text","data":"μ"}]},{"name":"text","data":"m，像素为400×400 pixel，每幅图像的扫描时间约为45 s。可以看出，除了因热漂移造成的少许平移之外，两幅图像具有很好的重复性和对比度。由于恒力模式的对比度会比等高模式稍低，因此纳米压印结构的棱角显得较为圆滑，而且在"},{"name":"xref","data":{"text":"图 4","type":"fig","rid":"Figure4","data":[{"name":"text","data":"图 4"}]}},{"name":"text","data":"(等高模式图像)中基底上更细小的纳米颗粒，在恒力模式下基本不可见，这正是恒力模式的特点之一。需要指出，由于是在不同月份重新安装上样品后进行扫描成像的，因此"},{"name":"xref","data":{"text":"图 5","type":"fig","rid":"Figure5","data":[{"name":"text","data":"图 5"}]}},{"name":"text","data":"与"},{"name":"xref","data":{"text":"图 4","type":"fig","rid":"Figure4","data":[{"name":"text","data":"图 4"}]}},{"name":"text","data":"的图像并不是同一区域。上述实验表明，本文研发的AFM系统可以很好地实现等高模式和恒力模式的扫描成像。"}]},{"name":"fig","data":{"id":"Figure5","caption":[{"lang":"zh","label":[{"name":"text","data":"图5"}],"title":[{"name":"text","data":"恒力模式下纳米压印阵列的AFM图像"}]},{"lang":"en","label":[{"name":"text","data":"Fig 5"}],"title":[{"name":"text","data":"AFM images of nano-imprint structures under constant force mode"}]}],"subcaption":[],"note":[],"graphics":[{"print":"http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=1709761&type=","small":"http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=1709761&type=small","big":"http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=1709761&type=middle"}]}},{"name":"p","data":[{"name":"text","data":"需要再次指出，上述扫描成像实验均在室外进行，无需交流市电和直流高压电源，基于WiFi无线数据通信实现AFM的扫描成像，由此表明该AFM系统具有优良而又独特的性能。"}]}]},{"name":"sec","data":[{"name":"sectitle","data":{"label":[{"name":"text","data":"5"}],"title":[{"name":"text","data":"结论"}],"level":"1","id":"s5"}},{"name":"p","data":[{"name":"text","data":"本文提出了一种基于嵌入式系统和WiFi的无线控制式AFM技术，成功研发了相应的AFM系统，开展了微纳米样品的扫描成像实验。实验结果表明，该AFM系统的横向分辨率达到纳米量级，纵向分辨率达到0.1 nm，最大扫描范围为3.6 "},{"name":"italic","data":[{"name":"text","data":"μ"}]},{"name":"text","data":"m×3.6 "},{"name":"italic","data":[{"name":"text","data":"μ"}]},{"name":"text","data":"m，并具有良好的对比度和重复性。该系统的显著特点是无需交流市电供电，无需直流高压电源，也无需与计算机之间的线缆连接，可通过无线控制的方式实现AFM的扫描成像，克服了常规AFM的局限性。这一新型AFM系统不仅能够应用于常规领域及常规环境，而且能够广泛应用于野外考察、隔离环境、真空条件、气体氛围环境及星际探测等特殊领域。"}]}]}],"footnote":[],"reflist":{"title":[{"name":"text","data":"参考文献"}],"data":[{"id":"b1","label":"1","citation":[{"lang":"en","text":[{"name":"text","data":"ZHANG S, SHAO Y, LIAO H G, et al.. 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