Magnetic domain imaging with a scanning near-field optical microscope using a modified Sagnac interferometer

We report on the combination of a scanning near-field optical microscope and a modified Sagnac interferometer for magnetic-domain imaging in the reflection mode. The Sagnac interferometer is used for detection of the magneto-optical Kerr effect. Since the interferometer is inherently insensitive to polarization changes caused by topography effects, magnetic-domain imaging is not limited to samples with flat surfaces. In this way, it is possible to image magnetic bits written on the tracks of a magneto-optical disc that has a rather pronounced surface profile.     

压电微音叉扫描探针显微镜测头研究

压电微音叉具有良好的谐振特性，并易于实现其振动的检测。利用这些特性，与钨探针结合，构成了一种新型的表面轮廓扫描测头。该新型测头与X-Y压电工作台结合，采用与TM-AFM相同的工作原理，构成了扫描探针显微镜。介绍了压电微音叉扫描测头的构成、工作原理及主要特性，给出了所构成的扫描探针显微镜测量系统。通过实验及其结果，证明了新型测头具有高垂直分辨率、低破坏力等优点。除此之外，由于采用了有效长度大的钨探针，使大台阶微观表面的测量成为可能。     

Multi-objective optimal design of high frequency probe for scanning ion conductance microscopy

Scanning ion conductance microscopy(SICM) is an emerging non-destructive surface topography characterization apparatus with nanoscale resolution. However, the low regulating frequency of probe in most existing modulated current based SICM systems increases the system noise, and has difficulty in imaging sample surface with steep height changes. In order to enable SICM to have the capability of imaging surfaces with steep height changes, a novel probe that can be used in the modulated current based hopping mode is designed. The design relies on two piezoelectric ceramics with different travels to separate position adjustment and probe frequency regulation in the Z direction. To further improve the resonant frequency of the probe, the material and the key dimensions for each component of the probe are optimized based on the multi-objective optimization method and the finite element analysis. The optimal design has a resonant frequency of above 10 kHz. To validate the rationality of the designed probe, microstructured grating samples are imaged using the homebuilt modulated current based SICM system. The experimental results indicate that the designed high frequency probe can effectively reduce the spike noise by 26% in the average number of spike noise. The proposed design provides a feasible solution for improving the imaging quality of the existing SICM systems which normally use ordinary probes with relatively low regulating frequency.     

Evaluation of fracture planes and cell morphology in complementary fractures of cultured cells in the frozen-hydrated state by field-emission secondary electron microscopy: feasibility for ion localization and fluorescence imaging studies

We have employed field-emission secondary electron microscopy (FESEM) for morphological evaluation of freeze-fractured frozen-hydrated renal epithelial LLC-PK₁ cells prepared with our simple cryogenic sandwich-fracture method that does not require any high-vacuum freeze-fracture instrumentation (Chandra et al. (1986) J. Microsc. 144 , 15–37). The cells fractured on the substrate side of the sandwich were matched one-to-one with their corresponding complementary fractured faces on the other side of the sandwich. The FESEM analysis of the frozen-hydrated cells revealed three types of fracture: (i) apical membrane fracture that produces groups of cells together on the substrate fractured at the ectoplasmic face of the plasma membrane; (ii) basal membrane fracture that produces basal plasma membrane-halves on the substrate; and (iii) cross-fracture that passes randomly through the cells. The ectoplasmic face (E-face) and protoplasmic face (P-face) of the membrane were recognized based on the density of intramembranous particles. Feasibility of fractured cells was shown for intracellular ion localization with ion microscopy, and fluorescence imaging with laser scanning confocal microscopy. Ion microscopy imaging of freeze-dried cells fractured at the apical membrane revealed well-preserved intracellular ionic composition of even the most diffusible ions (total concentrations of K⁺, Na⁺ and Ca⁺). Structurally damaged cells revealed lower K⁺ and higher Na⁺ and Ca⁺ contents than in well-preserved cells. Frozen-freeze-dried cells also allowed imaging of fluorescently labelled mitochondria with a laser scanning confocal microscope. Since these cells are prepared without washing away the nutrient medium or using any chemical pretreatment to affect their native chemical and structural makeup, the characterization of fracture faces introduces ideal sample types for chemical and morphological studies with ion and electron microscopes and other techniques such as laser scanning confocal microscopy, atomic force microscopy and near-field scanning optical microscopy.     

智能聚合物锂电池放电特性测试仪

聚合物锂离子电池广泛应用于各类便携式电子产品,电池的放电特性直接影响电子产品的可靠性。电池放电特性的人工检测方法既繁琐又容易出错,因此设计了智能电池放电特性检测系统,检测系统以MSP430单片机为控制核心,自动记录恒定电流放电时的电池电压及环境温度,设计了过放电保护电路防止电池过放电。使用该检测系统对多种容量的聚合物锂离子电池进行了放电试验,获得了电池在高温、低温和常温环境下的放电特性,为电子产品的工作可靠性提供了保障。     

扫描离子电导显微镜技术及其在纳米生物学研究中的应用

扫描探针显微镜技术的出现开辟生命科学研究的新纪元并逐步发展成为在纳米尺度研究细胞结构与功能的一类新型的显微镜技术。扫描离子电导显微镜技术就是新近发展起来的这一扫描探针显微镜技术家族中的一员,可被用来在生理条件下、高分辨率及非接触地研究活细胞的表面形貌,从而帮助人们深入研究细胞微观结构与功能的关系。本文简要介绍扫描离子电导显微镜技术的基本原理,并结合国外研究现状综述该技术在纳米生物学研究中的应用。     

Scanning (atomic) force microscopy imaging of earthworm haemoglobin calibrated with spherical colloidal gold particles

Scanning (atomic) force microscopy (SFM) permits high-resolution imaging of a biological specimen in physiological solutions. Untreated extracellular haemoglobin molecules of the common North American earthworm, Lumbricus terrestris, were imaged in NH₄Ac solution using calibrated SFM. Individual molecules and their top and side views were clearly identified and were comparable with the images of the same molecule obtained by scanning transmission electron microscopy (STEM). A central depression, the presumed mouth of the hole, was detected. We analysed 75 individual molecules for their lateral dimensions. Compression varied for different molecules, presumably because of the variation of the interaction between the SFM tip and the protein molecule. Two effective heights which correspond to the heights of the points of the haemoglobin molecules first and last touched by the tip, h₁ and h₂, respectively, were measured for each protein and ranged between 1.58 and 16.2 nm for h₁ and 1.23 and 13.6 nm for h₂. The apparent diameter was measured and ranged from 44.9 to 86.6 nm (63.2±10.5 nm, n =75), which is about twice the diameter of the molecule reported by STEM for the top view orientation. The higher the measured effective heights, the worse was the tip convolution effect. In order to determine the tip parameters (semivertical angle, curvature of radius and the cut-off height) and to calibrate images of earthworm haemoglobin molecules, spherical gold particles were scanned as standards. The tip sectional radii at distances of h₁ and h₂ above the tip apex were subtracted from the apparent diameter of the protein. The calibrated lateral dimension was 29.1 ±3.85 nm, which is close to the reported scanning transmission electron microscopy data 30.0 ±0.8 nm. The results presented here demonstrate that the calibration approach of imaging gold particles is practical and relatively accurate. Calibrated SFM imaging can be applied to the study of other biomacromolecules.     

Scanning probe microscopy of biological samples and other surfaces

Scanning probe microscopes derived from the scanning tunnelling microscope (STM) offer new ways to examine surfaces of biological samples and technologically important materials. The surfaces of conductive and semiconductive samples can readily be imaged with the STM. Unfortunately, most surfaces are not conductive. Three alternative approaches were used in our laboratory to image such surfaces. 1. Crystals of an amino acid were imaged with the atomic force microscope (AFM) to molecular resolution with a force of order 10^?8 N. However, it appears that for most biological systems to be imaged, the atomic force microscope should be able to operate at forces at least one and perhaps several orders of magnitude smaller. The substitution of optical detection of the cantilever bending for the measurement by electron tunnelling improved the reliability of the instrument considerably. 2. Conductive replicas of non-conductive surfaces enabled the imaging of biological surfaces with an STM with a lateral resolution comparable to that of the transmission electron microscope. Unlike the transmission electron microscope, the STM also measures the heights of the features. 3. The scanning ion conductance microscope scans a micropipette with an opening diameter of 0·04-0·1 μm at constant ionic conductance over a surface covered with a conducting solution (e.g., the surface of plant leaves in saline solution).     

锂离子电池膨胀特性检测方法研究进展

锂离子电池凭借其高能量密度和长循环寿命等优势被广泛应用于便携式电子设备、电动汽车、储能系统等领域。 然而在锂离子电池的反复充放电使用过程中,会出现可逆的嵌锂膨胀和过充过放等原因导致的不可逆的膨胀,且后者是影响锂离子电池循环寿命等性能的重要因素。 因此,研究锂离子电池的膨胀特性,有助于进一步了解电池老化机理,进而指导电池系统的安全设计,在新能源汽车及储能领域有巨大的应用价值。 本文基于此,结合应用场景总结了外置传感器、内置传感器以及数字成像技术等检测方法应用于锂离子电池膨胀特性研究的现状与进展,同时讨论分析了各类方法的主要优缺点,并展望了锂离子电池膨胀特性检测技术的发展趋势和未来前景。     

MEMS-based fast scanning probe microscopes

Scanning probe microscopy is a frequently used nanometer-scale surface investigation technique. Unfortunately, its applicability is limited by the relatively low image acquisition speed, typically seconds to minutes per image. Higher imaging speeds are desirable for rapid inspection of samples and for the study of a range of dynamic surface processes, such as catalysis and crystal growth. We have designed a new high-speed scanning probe microscope (SPM) based on micro-electro mechanical systems (MEMS). MEMS are small, typically micrometer size devices that can be designed to perform the scanning motion required in an SPM system. These devices can be optimized to have high resonance frequencies (up to the MHz range) and have very low mass (10⁻¹¹ kg). Therefore, MEMS can perform fast scanning motion without exciting resonances in the mechanical loop of the SPM, and hence scan the surface without causing the image distortion from which conventional piezo scanners suffer. We have designed a MEMS z-scanner which we have integrated in commercial AFM (atomic force microscope) and STM (scanning tunneling microscope) setups. We show the first successful AFM experiments.     

SNOM/SFM结合的近场光学探针

介绍了近年来近场光学探针技术的进展，特别是可与扫描力显徽镜结合的探针制备技术。     

Nanoscale fretting wear study by scanning probe microscopy

Nanoscale fretting wear was studied by using scanning probe microscopy (SPM) and a newly proposed unified approach of slip index. The production of SiO₂ colloidal probes and the SPM calibration are described. Partial and gross slip fretting with displacement amplitudes from 5 to 500 nm were used for the study. Friction coefficient and nanowear results are presented showing a substantial increase of the friction at the transition from partial to gross slip and a significant difference between damaged surfaces in the two fretting regimes.     

Three-dimensional image formation in confocal microscopy

Three-dimensional (3-D) imaging in confocal microscopes is considered in terms of 3-D transfer functions. This leads to an explanation of axial imaging properties. The axial response was observed in both object-scanning and beam-scanning microscopes and the influence of off-axis examination investigated. By simple processing of multi-detector signals, imaging in both the axial and transverse directions can be improved.     

一种基于单片机的智能充电器设计

介绍一种基于单片机的智能充电器的硬件和软件实现。该充电器可以实时采集和计算电池的参数，并进行智能控制，还可以通过串口和上位机进行通讯并进行实时显示，根据不同的电池调整充电策略。实验证明，该设计具有数字化、智能化、通用化和低功耗的特点。