A fully automated microfluidic-based detection system for the rapid determination of insulin concentration through a chemiluminescence immunoassay has been developed. The microfluidic chip used in the system is a double-layered polydimethylsiloxane device embedded with interconnecting micropumps, microvalves, and a micromixer. At a high injection rate of the developing solution, the chemiluminescence signal can be excited and measured within a short period of time. The integral value of the chemiluminescence light signal is used to determine the insulin concentration of the samples, and the results indicate that the measurement is accurate in the range from 1.5 pM to 391 pM. The entire chemiluminescence assay can be completed in less than 10min. The fully automated microfluidic-based insulin detection system provides a useful platform for rapid determination of insulin in clinical diagnostics for diabetes, which is expected to become increasingly important for future point-of-care applications.

为了得到纳米操作压电陶瓷驱动器高精度的驱动特性,提出一种基于显微视觉的亚像素位移测量方法.本文采用Harris角点初始定位,对标准的栅格图像序列进行角点匹配,获得模板匹配的初始区域.并提出了二元拉格朗日插值与二元非线性Newton-Raphson迭代算法的亚像素位移测量方法,能够在保证良好测量精度的同时有效地减少亚像素匹配中耗时的相关计算.最后使用改进的亚像素图像块匹配方法对实际的压电陶瓷驱动器的驱动特性进行了测量,并与真实结果和理论模型描述结果进行了对比.实验结果表明,该算法位移测量精度高,稳定性好,得到的压电陶瓷驱动特性曲线符合物理分析结果,能够满足高精度的微纳米测量要求.更多还原

研究了一种利用一般原子力显微镜（AFM）实现简便高效纳米操作的方法。利用AFM的成像功能及AFM探针的刻划功能,记录并测量压电陶瓷管（PZT）在X和Y两个方向的位移特性,解决了一般AFM无法检测自身PZT在X和Y两个方向位移的问题;采用PrandtlIshlinskii（PI）模型对PZT的迟滞非线性特性进行建模并建立前馈控制器,以解决AFM探针任意运动路径的驱动问题;采用虚拟纳米手策略对AFM探针的运动路径进行设计,通过构建的前馈控制器驱动AFM探针,完成了15μm×15μm范围内对直径200 nm聚苯乙烯颗粒的连续折线推动,并对长约1.3μm的银棒进行了固定姿态连续平移操作,推动距离超过5μm,整个过程因减少了局部扫描环节而使平均单次操作时间减小到10 s以内。

CuO nanowire is an important one-dimensional semiconductor material to assemble and fabricate novel nanoelectronic device, especially molecular or atom device based on single nanowire. However, how to assemble and fabricate nanoelectronic device based on single CuO nanowire remains a big challenge. Here, we proposed a new controllable dielectrophoresis assembly technology, namely dielectrophoretic working space-dielectrophoresis technology, to realize the assembly and fabrication of single CuO nanowire nanoelectronic device. Theoretical analysis and assembly experiments verified the effectiveness of the new technology. By this technology, currently we have successfully fabricated two kinds of single CuO nanowire nanoelectronic device, photodetector and alcohol sensor, from CuO nanowire's preparation, dispersion to assembly. Due to the high sensitivity of single CuO nanowire, the novel alcohol sensor can work at room temperature compared to the CuO nanowires arrays-based sensor working only at high temperature. The proposed technology can also be utilized to assemble and fabricate single-nanowire electronic device based on other materials.

Zinc oxide (ZnO) nanorods with branches are synthesised through facile hydrothermal approach at relatively low temperature. With the prepared ZnO nanostructures as the hole-blocking layer, organic solar cells based on poly(3-hexylthiophene): 1-(3-methoxycarbonyl)propyl-1-phenyl[6,6]C61 are fabricated. For comparison, devices with planar ZnO thin film and bare ZnO nanorods are manufactured as well. J-V curves show that the best device performance is achieved by the branched nanorod-based solar cell. Owing to the decreased charge carrier travelling length, the nanorod-based device shows higher short circuit current (J(sc)) than that of the device with planar ZnO layer. Moreover, the solar cell with branched nanorods shows larger open-circuit voltage (V-oc) than that with bare nanorods. Therefore, the performance of organic photovoltaic is enhanced with the introduction of branched ZnO nanorods. Finally, the mechanism of device performance improvement upon the introduction of branched nanorods is discussed.

A modified Prandtl–Ishlinskii (PI) model, referred to as a direct inverse asymmetric PI (DIAPI) model in this paper, was implemented to reduce the displacement error between a predicted model and the actual trajectory of a piezoelectric actuator which is commonly found in AFM systems. Due to the nonlinearity of the piezoelectric actuator, the standard symmetric PI model cannot precisely describe the asymmetric motion of the actuator. In order to improve the accuracy of AFM scans, two series of slope parameters were introduced in the PI model to describe both the voltage-increase-loop (trace) and voltage-decrease-loop (retrace). A feedforward controller based on the DIAPI model was implemented to compensate hysteresis. Performance of the DIAPI model and the feedforward controller were validated by scanning micro-lenses and standard silicon grating using a custom-built AFM.

As one of the most crucial properties of DNA, the structural stability and the mechanical strength are attracting a great attention. Here, we take advantage of high force resolution and high special resolution of Atom Force Microscope and investigate the mechanical force of DNA duplexes. To evaluate the base pair hydrogen bond strength and base stacking force in DNA strands, we designed two modes (unzipping and stretching) for the measurement rupture forces. Employing k-means clustering algorithm, the ruptured force are clustered and the mean values are estimated. We assessed the influence of experimental parameters and performed the force evaluation for DNA duplexes of pure dG/dC and dA/dT base pairs. The base binding strength of single dG/dC and single dA/dT were estimated to be 20.0 ± 0.2 pN and 14.0 ± 0.3 pN, respectively, and the base stacking interaction was estimated to be 2.0 ± 0.1 pN. Our results provide valuable information about the quantitative evaluation of the mechanical properties of the DNA duplexes.

“核心”DNA纳米结构的精确定位是实现指定位置的DNA纳米结构可控自组装构建纳米器件或系统的关键难题之一.研究了一种可编程控制的原子力显微镜(AFM)操作方法,通过运用操作过程中参数调控,实现液体环境中柔性DNA纳米结构的可控定位及定向操作.对操作振幅和溶液中Mg2+浓度两个关键参数进行了实验优化.实验采用的是长400 nm和直径约6 nm的DNA纳米管状结构.实验结果表明,在操作振幅为3.5 nm和Mg2+浓度为10 mmol/L的优化控制条件下,应用可编程控制的AFM调控操作方法,实现了液体环境中DNA纳米结构的定位定向操作,且成功率达到80％.

CAS Key Laboratory of Measurement and Standardization for Nanotechnology, National Center for Nanoscience and Technology, Beijing 100190, People’s Republic of China University of Chinese Academy of Sciences, Beijing 100190, People’s Republic of China School of Materials Science and Engineering, Shandong University, Jinan 250100, People’s Republic of China tangy@nanoctr.cn,chuly@nanoctr.cn,liurx@nanoctr.cn, gegl@nanoctr.cn Corresponding authors

原子力显微镜（AFM）通常采用压电陶瓷（PZT）作为驱动器以实现纳米尺度的观测和操作。然而,PZT自身的迟滞非线性会对AFM观测质量和操作精度产生很大影响。基于Prandtl-Ishlinskii（PI）模型的前馈控制方法可对PZT的迟滞非线性进行补偿,但传统PI模型无法消除PZT的非对称迟滞性的影响。针对这个问题,提出一种基于梯形算子的非对称迟滞模型,并可用系统辨识方法获取逆模型参数,该方法可有效实现具有非对称迟滞特性驱动器的前馈补偿控制。AFM系统实验证明,该模型可有效减小非对称迟滞性导致的建模误差,基于该模型的前馈迟滞补偿控制可有效提高AFM的扫描成像质量。

The imaging properties of a microlens are highly related to its 3-D profile; therefore, it is of fundamental importance to measure its 3-D geometrical characteristics with high accuracy after industrial fabrication. However, common 3-D measurement tools are difficult to use for fast, noninvasive, and precise 3-D measurement of a microlens. Depth acquisition is a direct way to understand the 3-D properties of objects in computer vision, and shape from defocus (SFD) has been demonstrated to be effective for 3-D reconstruction. In this paper, a depth reconstruction method from blurring using optical microscopy and optical diffraction is proposed to reconstruct the global shape of a microlens. First, the relationship between the intensity distribution and the depth information is introduced. Second, a blurring imaging model with optical diffraction is formulated through curve fitting, accounting for relative blurring and heat diffusion, and a new SFD method with optical diffraction and defocused images is proposed. Finally, a polydimethylsiloxane (PDMS) microlens is used to validate the proposed SFD method, and the results show that its global shape can be reconstructed with high precision. The average estimation error is 77 nm, and the cost time is reduced by 92.5% compared with atomic force microscopy scanning.

Nowadays,one of the bottlenecks which hinder the development and application of carbon nanotube(CNT)nano device is that no pure semiconducting CNT(s-CNT)or metallic CNT(m-CNT)can be obtained,and for solving this problem scientists proposed some methods on preparation or separation,but all the results still should be detected and feedback to the process for further improving the preparation and separation methods.Thus,it is very important to measure and distinguish the electrical properties of CNT.For that,scientists proposed a method to measure CNT electrical properties based on DC electrostatic force microscope(EFM)mode,which distinguishes m-CNT from s-CNT according to different scan line shape to CNT with different electrical properties.But,we discovered that the probe lift-up height will seriously affect the shape of the scan line,which makes this method not reliable in distinguishing m-CNT from s-CNT.In this paper,the authors deeply researched the influence of probe lift-up height and also gave corresponding theoretical analysis and explanation,which will greatly improve the method of detecting CNT electrical properties by EFM.

Traditional depth from defocus (DFD) is based on the imaging principle in geometric optics to calculate blurring degree, influence of optical diffraction has never been considered. However, diffraction is a basic property of all kinds of waves, it must happen in an optical imaging system based on pinhole imaging principle. In this paper, a high resolution DFD method with a single vision and optical diffraction is given. Firstly, the basic principle of Fresnel diffraction in an optical system is analyzed, and the relationship curve between Fresnel diffraction and depth information is constructed. Secondly, a defocus imaging model with optical diffraction is supposed through curve fitting, and with respect to relative blurring and heat diffusion, a new DFD method with optical diffraction and two defocused images is proposed. Finally, a standard nano grid is used to validate the proposed DFD method on nana scale. The results show that the new algorithm, compared with traditional DFD algorithms, is a more effective method to reconstruct depth information on nano scale.

液体混合是微流控芯片的重要功能之一,微流控液体混合方式可分为主动式和被动式两种.针对目前微流控混合器存在的被动式混合效率不高和主动式混合器制作工艺复杂等问题,研究设计了一种基于雕刻机加工的低成本、高效率气动式微流控混合器.该微流控芯片采用数控雕刻机快速加工微模具,经PDMS固化、翻模、打孔和键合等工艺,实现了微流控混合器的制作.同时研究设计了多气室脉冲气体驱动模式,有效实现了微量试剂和样品的快速混合.实验结果表明,所研究的主动式微流控混合器可以产生对流混沌作用,显著提高微尺度下的混合效率,为实现低成本的微流控芯片制作和高效试剂混合的MEMS生化检测系统提供了一种有效的技术途径.

Atomic force microscopy (AFM) has been widely applied in the field of science and technology because it can observe and manipulate at the nanometer scale. The piezoelectric is a regular choice for the actuator of AFM because of its high resolution and fast response. However, the intrinsic hysteresis nonlinearity weakens the accuracy of the observation and manipulation of AFM. Aiming at the hysteresis problem of the piezoelectric actuators in AFM, a modified feedforward calibration method based on the Prandtl-Ishlinskii (PI) model was proposed. By the means of identify the parameters of inverse model directly, the modified method simplify the obtaining procedure for the PI inverse model. The restriction to obtain the inverse model was removed, and the computational complexity was decreased. Experiments validate that the method is effective in reducing errors due to hysteresis, and improving AFM image quality.

Early stage detection of lymphoma cells is invaluable for providing reliable prognosis to patients. However, the purity of lymphoma cells in extracted samples from human patients' marrow is typically low. To address this issue, we report here our work on using optically-induced dielectrophoresis (ODEP) force to rapidly purify Raji cells' (a type of Burkitt's lymphoma cell) sample from red blood cells (RBCs) with a label-free process. This method utilizes dynamically moving virtual electrodes to induce negative ODEP force of varying magnitudes on the Raji cells and RBCs in an optically-induced electrokinetics (OEK) chip. Polarization models for the two types of cells that reflect their discriminate electrical properties were established. Then, the cells' differential velocities caused by a specific ODEP force field were obtained by a finite element simulation model, thereby established the theoretical basis that the two types of cells could be separated using an ODEP force field. To ensure that the ODEP force dominated the separation process, a comparison of the ODEP force with other significant electrokinetics forces was conducted using numerical results. Furthermore, the performance of the ODEP-based approach for separating Raji cells from RBCs was experimentally investigated. The results showed that these two types of cells, with different concentration ratios, could be separated rapidly using externally-applied electrical field at a driven frequency of 50 kHz at 20 V-pp. In addition, we have found that in order to facilitate ODEP-based cell separation, Raji cells' adhesion to the OEK chip's substrate should be minimized. This paper also presents our experimental results of finding the appropriate bovine serum albumin concentration in an isotonic solution to reduce cell adhesion, while maintaining suitable medium conductivity for electrokinetics-based cell separation. In short, we have demonstrated that OEK technology could be a promising tool for efficient and effective purification of Raji cells from RBCs.

The observation of friction anisotropy on graphene by friction measurement at atomic scale has been reported in this paper. Atomic-scale friction measurement revealed friction anisotropy with a periodicity of 60°, which is consistent with the hexagonal periodicity of the graphene. Both experiments and theory show that the value of the friction force is related to the graphene lattice orientation, and the friction force along armchair orientation is also larger than the one along zigzag orientation. These results will play a critical role in the use of graphene to manufacture nanoscale devices.