扫描切变力/近场光学显微镜研制及应用

在发展光纤探针制备和探针与样品近场间距非光学控制等关键技术基础上，我们研制成能与倒置光学显微镜联合使用的扫描切变力／近场光学显微镜，并具有反射和透射等工作模式以及能在溶液环境中工作。利用这套系统，获得了多种样品的表面形貌和近场光学图像以及细胞内的荧光光谱。本文将对该系统和有关实验结果作简要介绍。     

铁电微阵列的AFM图像及电滞回线测定

铁电阵列在红外探测器、非挥发性存储器中具有重要应用。随着大面积、微格点铁电阵列制备技术的发展，评价亚微米、甚至纳米级微小格点的铁电特性对于铁电器件的设计和制造具有重要意义。本研究将铁电仪和扫描探针显微镜相连，在扫描探针显微镜的AFM模式下，采用带有导电涂层的探针，通过扫描获得铁电阵列的三维像。据此图像，可以把探针定位于特定的微小格点上，由铁电仪通过AFM探针提供电压，并经探针悬臂梁将测试信号反馈给铁电仪，在无顶电极的情况下就可以获得微小铁电格点的电滞回线。     

一种新型的STM探针

以普通的石英光纤为材料，用熔拉腐蚀复合的方法制备出nm量级的光纤探针，而后在针尖表面镀上数十nm厚的金属膜，达到导电性，使其能传导隧道电流，从而研制出一种新型的扫描隧道显微镜（STM）光纤隧道探针，在STM上取得了比较理想的实验结果。本文将光纤隧道探针与金属隧道探针作了比较，并对其性能作了分析。     

变温腐蚀法制备纳米光纤探针

通过改变温度,用腐蚀的方法制备出用于近场光学显微镜的光纤探针。通过控制光纤在不同温度的腐蚀液中腐蚀的时间,制备出多种形貌的光纤探针,所制作探针的锥形过渡区短而锥角大。该法具有重复性高、探针形貌可控、操作方便、实验费用低廉、制备的探针表面光滑等优点,利用该方法成功地制备出针尖尺寸50～300nm、针尖锥角在40°～74°可调的光纤探针。将制备的探针用于扫描全息光栅(500线/mm),结果在40mm范围内扫描有20个周期,与全息光栅的标定结果相符。     

自组装金纳米粒子薄膜AFM研究

以化学还原法制备了金胶体,采用静电吸附自纽装法在单晶硅片表面制备了金纳米粒子薄膜,采用原子力显微镜分析了薄膜的表面形貌与结构。     

无测试图形薄层电阻测试仪及探针定位

研制出检测U L SI芯片的薄层电阻测试仪,可用于测试无图形样片电阻率的均匀性,用斜置的方形四探针法,经显微镜、摄像头及通信口接入计算机,从计算机显示器观察,用程序及伺服电机控制平台和探针移动,使探针处于规定的位置,实现自动调整、测试;对测试系统中的探针游移造成的定位误差进行分析,推导出探针游移产生误差的计算公式,绘制了理论及实测误差分布图;测出无图形10 0 m m样品电阻率,并绘制成等值线Mapping图.     

无测试图形薄层电阻测试仪及探针定位

研制出检测ULSI芯片的薄层电阻测试仪,可用于测试无图形样片电阻率的均匀性,用斜置的方形四探针法,经显微镜、摄像头及通信口接入计算机,从计算机显示器观察,用程序及伺服电机控制平台和探针移动,使探针处于规定的位置,实现自动调整、测试;对测试系统中的探针游移造成的定位误差进行分析,推导出探针游移产生误差的计算公式,绘制了理论及实测误差分布图;测出无图形100mm样品电阻率,并绘制成等值线Mapping图.     

采用静电自组装技术在光纤上制备光学薄膜的研究

采用静电自组装技术在石英玻璃光纤和显微镜载玻片上制备了二氧化钛胶体与阴离子聚电解质PSS、二氧化硅胶体与阳离子聚电解质PDDA的复合薄膜，研究了薄膜的光反射性能，在光纤端面上交替沉积光学厚度为λ/4的PDDA/SiO2低折射率薄膜，可以获得λ/4多层反射膜，使样品表面的反射性能大大提高。     

扫描探针显微镜在胶原纤维精细结构研究中的应用

作为一种新型的微区分析仪器，扫描探针显微镜已迅速普及和应用到了各门学科，而在生物领域的应用则相对比较落后。本文简要介绍了扫描探针显微镜这一新型表面测试技术在猪皮胶原精细结构研究中的应用方法，并将所得结果与透射电镜结果进行了比较分析。     

非接触式扫描离子电导显微镜技术在探测活体细胞表面微结构中的应用

扫描离子电导显微镜技术是在纳米尺度进行非导电的生物样品成像的一种新型扫描探针显微镜技术。通过成功制备扫描离子电导显微镜扫描探测用纳米尺度玻璃微探针,对其进行了功能性评估;而后通过绘制探针-样品接近曲线,阐述了扫描离子电导显微镜技术实现非接触高分辨率探测的工作原理;最后采用该显微镜技术对导电标准样品及活体肾上皮A6细胞进行了表面形貌扫描成像,并与A6细胞表面形貌的扫描电镜图像进行了对照。结果表明,扫描离子电导显微镜技术不仅可实现导电样品的扫描成像,而且适宜于在生理条件下、非接触式地研究活体细胞表面的三维形貌,从而为人们深入研究细胞表面微观结构与生理功能提供了全新的技术手段。     

Fabrication of Ordered Nanostructured Arrays Using Poly(dimethylsiloxane) Replica Molds Based on Three‐Dimensional Colloidal Crystals

Hexagonally arrayed structures of colloidal crystals with uniform surface are a good candidate for master molds to be used in soft lithography. Here, the fabrication of periodically arrayed nanostructures using poly(dimethylsiloxane) (PDMS) molds based on three‐dimensionally (3D) ordered colloidal crystals is reported. A robust, high‐quality 3D colloidal‐crystal master molds is prepared using the colloidal suspension containing a water‐soluble polymer. The surface patterns of the 3D colloidal crystals can then be transferred onto a polymer film via soft lithography, by means of the replication of the surface pattern with PDMS. Various hexagonally arrayed nanostructure patterns can be fabricated, including close‐packed and non‐close‐packed 2D arrays and honeycomb structures by the structural modification of the 3D colloidal‐crystal templates. The replicated hexagonally arrayed structures can also be used as templates for producing colloidal crystals with 2D superlattices.     

A high-yield microassembly structure for three-dimensional microelectrode arrays

This paper presents a practical microassembly process for three-dimensional (3-D) microelectrode arrays for recording and stimulation in the central nervous system (CNS). Orthogonal lead transfers between the micromachined two-dimensional probes and a cortical surface platform are formed by attaching gold beams on the probes to pads on the platform using wire-free ultrasonic bonding. The low-profile (150 microns) outrigger design of the probes allows the bonding of fully assembled high-density arrays. Micromachined assembly tools allow the formation of a full 3-D probe array within 30 min. Arrays having up to 8 x 16 shanks on 200-micron centers have been realized and used to record cortical single units successfully. Active 3-D probe arrays containing on-chip CMOS signal processing circuitry have also been created using the microassembly approach. In addition, a dynamic insertion technique has been explored to allow the implantation of high-density probe arrays into feline cortex at high-speed and with minimal traumatic injury.     

两种薄层电阻测试系统探针游移误差的对比分析

从理论上分析方形四探针和直线四探针薄层电阻测试方法中探针游移所造成的系统偏差,推导出计算游移偏差的公式,并作图展示探针游移后的电阻与理想值之比的分布情况,分析了两种四探针测试方法出现最大误差的情况。用方形四探针测试方法不仅比普通直线四探针测试方法所测量的微区小,而且方形四探针测量的游移偏差小于直线四探针测量所产生的偏差。经试验发现,实际测试过程中,方形四探针只要在合理压力范围内,探针游移完全在合理范围内,能够保证测试的准确性。     

Waveguide Technique for the Calibration of Miniature Implantable Electric-Field Probes for Use in Microwave-Bioeffects Studies

A new S-band waveguide technique has been developed for the calibration of miniature probes used in determining electric fields in biological tissues at 2.45 GHz. A section of waveguide is filled with tissue-equivalent liquid separated from the air-filled waveguide by a very thin (0.25-mm) planar dielectric spacer. The probe response is measured as a function of position on each side of the spacer and extrapolated to the interface. The ratio of probe response in air to that in test liquid is then determined assuming continuity of tangential E-field across the spacer. In the water-glycerol solution modelling wet tissue, the probes are 3.0+-0.6 times more sensitive to E/sup 2/ than in air. A wide variety of both wet and dry tissues may be simulated using liquids of different dielectric properties--a check on the properties is provided by comparing the measured depth of penetration of the wave in the liquid with the calculated value. Problems using the probes in biological tissues are also discussed.     

麦胚凝集素与纤维素酶胶体金探针的混合一步法标记

免疫金双标记技术可在超薄切片上同时标记两种不同的细胞组分,但传统的方法是用各个探针分别进行标记处理,费时费力,且两次标记有时相互干扰。本文通过对麦胚凝集素与纤维素酶两种胶体金探针标记条件与标记活性、标记特异性之间关系的分析,实现了在一定条件下两种探针混合的一步法双标记,极大地提高了工作效率,减少了非特异性背景。     

用3D-FDTD法分析用于近场光存储的光纤探针电磁波传输特性

提高近场光存储的存储信息密度的关键主要在于掌握近场存储光纤探针的透光率、近场光斑直径尺寸以及场梯度等近场物理量。采用三维时域有限差分 (3D FDTD)法分析了可用于近场光存储的光纤探针尖的光学性质 ,对不同类型光纤的近场光场分布进行了数值计算 ,给出结果并进行比较 ,从光学性质的角度对其在近场光存储中的应用加以讨论。完全镀膜光纤尖在极近场处的光斑可获得 10nm的尺寸 ,远小于传统光纤光学聚焦的光斑尺寸大小。     

Noninvasive measurement of current in the human body forelectromagnetic dosimetry

Minimally perturbing, resistive, nonferrous probes were developed for noninvasively measuring hazardous currents induced in the human body by electromagnetic fields at 1-200 MHz. Each probe has a resistive toroidal coil that is placed around the leg or other body member. An electrostatic shield is required to limit capacitive coupling. A new shielded test fixture provides TEM fields for calibration with a voltage standing wave ratio (VSWR) less than 1.1 from 1 to 200 MHz. A man-sized phantom was exposed to the near field of a vertical monopole antenna at 29.9 MHz, and the value of the current measured in the leg with the probe is in reasonable agreement with measured heating. Analyses and experiments show that commercial ferrous current probes modify the circuit in which they are used, changing the current being measured. Less change is caused by the authors' nonferrous current probes     

光纤包层中的弱光探测技术

设计了一种用于探测光纤激光器系统中有源光纤中残余的弱泵浦光的方法。采用两种光纤探针对剥离涂覆层的有源光纤以及保留涂覆层的光纤进行了包层泄漏光的测试,优选出锥形探针作为弱光探测的光纤探针,并用该探针测得泄漏光与包层残余泵浦光的功率关系,发现二者呈线性关系并有对应的比例系数。通过该光纤探针的方法可实现快速确定有源光纤在激光器中的使用最佳长度,避免传统方法中对有源光纤进行多次切割、熔接再测试等操作,极大地提高了测试效率并降低了测试成本。试验同时发现,光纤探针在剥离涂覆层光纤上的探测效果优于未剥离涂覆层的光纤探测效果。     

Control of apex shape of the fiber probe employed in photonscanning tunneling microscope by a multistep etching method

In this paper, we discuss about the control of the shape of the very apex of a sharpened fiber probe used in photon scanning tunneling microscope (PSTM) by means of a method based on selective chemical etching. Under ambient conditions, through a multistep etching method proposed here, fiber probes with a flattened apex having a diameter of around 15-20 nm could be produced with high reproducibility. It has also been discovered that, during the etching process, the shape of the apex of the probe takes a rounded or a flattened shape with respect to the etching time in an almost cyclic fashion and such a phenomenon could help in understanding the mechanism of the etching process. These kind of probes with flat apex after metal coating are suitable for the fabrication of apertured probes used in PSTM and also for super tips which have a promising future as nanosensors in the fields of biology and biochemistry     

A new miniature magnetic field probe for measuringthree-dimensional fields in planar high-frequency circuits

A new noncontacting miniature magnetic field probe for measuring the surface current distribution on high-frequency planar circuits in x-, y-, z-directions in the 1-20 GHz band has been designed, fabricated and tested. The field probes have very small dimensions and do not need any connection to the operating circuit under test, therefore there is almost no perturbation of the circuit properties. This simple and practical magnetic field probes can be used to assist the design of microwave circuits, antenna diagnostics and to test products in industry. This paper describes the production procedure of the magnetic field probes, a scanning diagnostic system, measurement examples and comparisons between measurements and calculations. The measurement results agree very well with theoretically expected field distributions