This paper introduces a paradigm shift in atomic force microscope(AFM)scan control,leveraging an artificial intelligence(AI)-based controller.In contrast to conventional control methods,which either show a limited per...This paper introduces a paradigm shift in atomic force microscope(AFM)scan control,leveraging an artificial intelligence(AI)-based controller.In contrast to conventional control methods,which either show a limited performance,such as proportional integral differential(PID)control,or which purely focus on mathematical optimality as classical optimal control approaches,our proposed AI approach redefines the objective of control for achieving practical optimality.This presented AI controller minimizes the root-mean-square control deviations in routine scans by a factor of about 4 compared to PID control in the presented setup and also showcases a distinctive asymmetric response in complex situations,prioritizing the safety of the AFM tip and sample instead of the lowest possible control deviations.The development and testing of the AI control concept are performed on simulated AFM scans,demonstrating its huge potential.展开更多
Efficiency and accuracy of AFM-based nanomanipulation are still major problems to be solved,due to the nonlinearities and uncertainties,such as drift,creep,hysteresis,etc. The deformation of cantilevers caused by mani...Efficiency and accuracy of AFM-based nanomanipulation are still major problems to be solved,due to the nonlinearities and uncertainties,such as drift,creep,hysteresis,etc. The deformation of cantilevers caused by manipulation force is also one of the most major factors of nonlinearities and uncertainties. It causes difficulties in precise control of the tip position and causes the tip to miss the position of the object. In order to solve this problem,the traditional approach is to use a rigid cantilever. However,this will significantly reduce the sensitivity of force sensing during manipulation,which is essential for achieving an efficient and reliable nanomanipulation. In this paper,a kind of active AFM probe has been used to solve this problem by directly controlling the cantilever’s flexibility or rigidity during manipu-lation. Based on Euller-Bernoulli Model,a kind of controller of the active probe employing Peri-odic-Output-Feedback(POF)law is implemented. The results of simulation and experiments have demonstrated that this theoretical model and POF controller are suitable for precise position control of nanomanipulation.展开更多
The history, characteristic, operation modes and coupling techniques of atomic force microscopy (AFM) are introduced. Then the application in cell biology is re- viewed in four aspects: cell immobilization methods, ce...The history, characteristic, operation modes and coupling techniques of atomic force microscopy (AFM) are introduced. Then the application in cell biology is re- viewed in four aspects: cell immobilization methods, cell im- aging, force spectrum study and cell manipulation. And the prospect of AFM application in cell biology is discussed.展开更多
为了扩大原子力显微镜(Atomic Force Microscope,AFM)使用范围,研制了一套大范围高速AFM系统。针对大范围高速扫描时Z方向控制问题,提出了前馈反馈混合控制方法。前馈控制包括自动调平前馈和基于前一行扫描前馈,前者通过多线扫描确定样...为了扩大原子力显微镜(Atomic Force Microscope,AFM)使用范围,研制了一套大范围高速AFM系统。针对大范围高速扫描时Z方向控制问题,提出了前馈反馈混合控制方法。前馈控制包括自动调平前馈和基于前一行扫描前馈,前者通过多线扫描确定样品倾斜位置,将所有扫描点的倾斜位移差用函数式表达,然后将其换算为Z向驱动电压后驱动下扫描器运动;后者利用前一行扫描高度数据作为当前行Z向扫描器驱动的参考输入。反馈控制为在普通比例-积分(PI)控制基础上改进的动态P参数PI控制,P参数设置与误差大小有关。实验结果表明:采用本控制方法最大控制误差由40.17nm减小为6.01nm,误差均方根值由22.85nm减小为2.01nm,明显抑制了误差信号,提高了Z向控制效果,获得了更精确的高度图像。展开更多
在原子力显微镜(atomic force microscope,AFM)扫描样品时,控制参数调节困难,依赖于操作经验.本文基于在线动态模型辨识,提出了一种AFM系统广义预测自校正控制与成像方法.首先,利用CARIMA(controlled autoregressive and moving-average...在原子力显微镜(atomic force microscope,AFM)扫描样品时,控制参数调节困难,依赖于操作经验.本文基于在线动态模型辨识,提出了一种AFM系统广义预测自校正控制与成像方法.首先,利用CARIMA(controlled autoregressive and moving-average)参数模型来描述局部线性化后的AFM系统模型,并通过在线动态模型辨识得到线性化模型的参数;基于该模型,采用基于GPC(generalized predictive control)的优化方法,在线求解类PI(proportional integral)控制器的参数,进而得到一种具有控制参数自动调整功能的AFM成像方法.为了验证本文方法的有效性,进行了仿真与实验测试.结果表明,在AFM扫描速度不同或PI参数选择不恰当的情况下,该方法能够自动地调整控制器参数,从而减小控制误差,提高成像精度.展开更多
细胞机械特性作为一种无标签(Label-free)的生物标记,正得到越来越多的关注.然而现有进行细胞机械特性测量的方法多以手工模式进行,耗时长、效率低下,无法满足生物学统计分析对大批量样品测试的要求.针对该问题,本文在原子力显微镜(Atom...细胞机械特性作为一种无标签(Label-free)的生物标记,正得到越来越多的关注.然而现有进行细胞机械特性测量的方法多以手工模式进行,耗时长、效率低下,无法满足生物学统计分析对大批量样品测试的要求.针对该问题,本文在原子力显微镜(Atomic force microscopy,AFM)基础上,建立了一套高速自动化的细胞机械特性测量系统.该系统利用图像处理方法来识别细胞,利用局部扫描来实现AFM针尖和细胞相对位置的精确标定,进而不需要AFM成像就能实现细胞机械特性的连续测定,配合上程序化控制的运动载物平台,可以高速自动化完成大范围区域内细胞机械特性的批量规模化测量.实验结果表明,该系统可以使得细胞机械特性的测量效率提高27倍,从而为Label-free生物标记的批量化测试提供了技术支撑.展开更多
We describe a new method of fabricating a brush-like polystyrene layer anchored on the surface of the silicon substrate, which involves three steps, namely (i) the attachment of 3-methacryloxypropyltrimethoxysilane on...We describe a new method of fabricating a brush-like polystyrene layer anchored on the surface of the silicon substrate, which involves three steps, namely (i) the attachment of 3-methacryloxypropyltrimethoxysilane onto the silicon surface; (ii) the reaction of vinyl moiety at another extremity of the anchored 3-methacryloxypropyltrimethoxysilane to 4-Hydroxyl-2, 2, 6, 6-tetramethyl-1-piperidinyloxy (HTEMPO?) catalyzed by azobisisobutyronitrile (AIBN); (iii) living free radical grafting polymerization of styrene in the presence of HTEMPO?. The controllable living free radical polymerization permits accurate control of both the molecular weight and the polydispersity. X-photoelectron spectroscopy measurement proved that the alkoxyamine initiator layer forms on the silicon surface. XPS and Ellipsometry measurements showed that the poly-styrene chains were covalently anchored onto the silicon surface. The thickness of the grafted polymer layer can be accurately manipulated by altering the polymerization time. The new method allows synthesizing random copolymer and block copolymers by the sequential growth of monomers from the substrate surface.展开更多
While self-assembly is relatively well-known and widely used to form hierarchical structures and thin film coatings,controlled assembly is less known and utilized.Our prior work has demonstrated the concept of control...While self-assembly is relatively well-known and widely used to form hierarchical structures and thin film coatings,controlled assembly is less known and utilized.Our prior work has demonstrated the concept of controlled assembly of macromolecules such as star polymers[molecular weight(M_(w))∼383 kDa,hydrodynamic radius R∼13.8 nm]in droplets.This work extends this concept to smaller molecules,in this case,poly(ethylene glycol)bis-tetrazine(PEGbisTz,M_(w) 8.1 kDa,R∼1.5 nm).The key to controlled molecular assembly is to first deliver ultrasmall volumes(sub-fL)of solution containing PEG-bisTz to a substrate.The solvent evaporates rapidly due to the minute volume,thus forcing the assembly of solute,whose overall size and dimension are dictated by the initial liquid geometry and size.Using prepatterned surfaces,this work revealed that the initial liquid shape can be further tuned,and we could control the final assembly of solute such as PEGbisTz molecules.The degree of control was demonstrated by varying the micropatterns and delivery conditions.This work demonstrated the validity of controlled assembly for PEG-bisTz and enables three-dimensional(3D)nanoprinting of functional materials.The technology has promising applications in nanophotonics,nanoelectronics,nanocomposite materials,and tissue engineering.展开更多
基金funding from the EMPIR programme co-financed by the participating states and from the European Union’s Horizon 2020 research and innovation programme(20IND08‘MetExSPM’).
文摘This paper introduces a paradigm shift in atomic force microscope(AFM)scan control,leveraging an artificial intelligence(AI)-based controller.In contrast to conventional control methods,which either show a limited performance,such as proportional integral differential(PID)control,or which purely focus on mathematical optimality as classical optimal control approaches,our proposed AI approach redefines the objective of control for achieving practical optimality.This presented AI controller minimizes the root-mean-square control deviations in routine scans by a factor of about 4 compared to PID control in the presented setup and also showcases a distinctive asymmetric response in complex situations,prioritizing the safety of the AFM tip and sample instead of the lowest possible control deviations.The development and testing of the AI control concept are performed on simulated AFM scans,demonstrating its huge potential.
基金the National Natural Science Foundation of China (Grant No.60675050)
文摘Efficiency and accuracy of AFM-based nanomanipulation are still major problems to be solved,due to the nonlinearities and uncertainties,such as drift,creep,hysteresis,etc. The deformation of cantilevers caused by manipulation force is also one of the most major factors of nonlinearities and uncertainties. It causes difficulties in precise control of the tip position and causes the tip to miss the position of the object. In order to solve this problem,the traditional approach is to use a rigid cantilever. However,this will significantly reduce the sensitivity of force sensing during manipulation,which is essential for achieving an efficient and reliable nanomanipulation. In this paper,a kind of active AFM probe has been used to solve this problem by directly controlling the cantilever’s flexibility or rigidity during manipu-lation. Based on Euller-Bernoulli Model,a kind of controller of the active probe employing Peri-odic-Output-Feedback(POF)law is implemented. The results of simulation and experiments have demonstrated that this theoretical model and POF controller are suitable for precise position control of nanomanipulation.
基金supported by the National Natural Science Foundation of China(Grant No.20305011)the Nationa1 Science Fund for Distinguished Young Scholars(Grant No.20025311).
文摘The history, characteristic, operation modes and coupling techniques of atomic force microscopy (AFM) are introduced. Then the application in cell biology is re- viewed in four aspects: cell immobilization methods, cell im- aging, force spectrum study and cell manipulation. And the prospect of AFM application in cell biology is discussed.
文摘为了扩大原子力显微镜(Atomic Force Microscope,AFM)使用范围,研制了一套大范围高速AFM系统。针对大范围高速扫描时Z方向控制问题,提出了前馈反馈混合控制方法。前馈控制包括自动调平前馈和基于前一行扫描前馈,前者通过多线扫描确定样品倾斜位置,将所有扫描点的倾斜位移差用函数式表达,然后将其换算为Z向驱动电压后驱动下扫描器运动;后者利用前一行扫描高度数据作为当前行Z向扫描器驱动的参考输入。反馈控制为在普通比例-积分(PI)控制基础上改进的动态P参数PI控制,P参数设置与误差大小有关。实验结果表明:采用本控制方法最大控制误差由40.17nm减小为6.01nm,误差均方根值由22.85nm减小为2.01nm,明显抑制了误差信号,提高了Z向控制效果,获得了更精确的高度图像。
文摘在原子力显微镜(atomic force microscope,AFM)扫描样品时,控制参数调节困难,依赖于操作经验.本文基于在线动态模型辨识,提出了一种AFM系统广义预测自校正控制与成像方法.首先,利用CARIMA(controlled autoregressive and moving-average)参数模型来描述局部线性化后的AFM系统模型,并通过在线动态模型辨识得到线性化模型的参数;基于该模型,采用基于GPC(generalized predictive control)的优化方法,在线求解类PI(proportional integral)控制器的参数,进而得到一种具有控制参数自动调整功能的AFM成像方法.为了验证本文方法的有效性,进行了仿真与实验测试.结果表明,在AFM扫描速度不同或PI参数选择不恰当的情况下,该方法能够自动地调整控制器参数,从而减小控制误差,提高成像精度.
基金The Authors thank the support from the National Natural Science Foundation of China （Project Codes： 51005230） and the Education Department of Liaoning province science and technology research projects （Project Codes： L2015452）.
文摘细胞机械特性作为一种无标签(Label-free)的生物标记,正得到越来越多的关注.然而现有进行细胞机械特性测量的方法多以手工模式进行,耗时长、效率低下,无法满足生物学统计分析对大批量样品测试的要求.针对该问题,本文在原子力显微镜(Atomic force microscopy,AFM)基础上,建立了一套高速自动化的细胞机械特性测量系统.该系统利用图像处理方法来识别细胞,利用局部扫描来实现AFM针尖和细胞相对位置的精确标定,进而不需要AFM成像就能实现细胞机械特性的连续测定,配合上程序化控制的运动载物平台,可以高速自动化完成大范围区域内细胞机械特性的批量规模化测量.实验结果表明,该系统可以使得细胞机械特性的测量效率提高27倍,从而为Label-free生物标记的批量化测试提供了技术支撑.
基金supported by the National Natural Science Foundation of China(Grant Nos.20476101&NSFC-20074015).
文摘We describe a new method of fabricating a brush-like polystyrene layer anchored on the surface of the silicon substrate, which involves three steps, namely (i) the attachment of 3-methacryloxypropyltrimethoxysilane onto the silicon surface; (ii) the reaction of vinyl moiety at another extremity of the anchored 3-methacryloxypropyltrimethoxysilane to 4-Hydroxyl-2, 2, 6, 6-tetramethyl-1-piperidinyloxy (HTEMPO?) catalyzed by azobisisobutyronitrile (AIBN); (iii) living free radical grafting polymerization of styrene in the presence of HTEMPO?. The controllable living free radical polymerization permits accurate control of both the molecular weight and the polydispersity. X-photoelectron spectroscopy measurement proved that the alkoxyamine initiator layer forms on the silicon surface. XPS and Ellipsometry measurements showed that the poly-styrene chains were covalently anchored onto the silicon surface. The thickness of the grafted polymer layer can be accurately manipulated by altering the polymerization time. The new method allows synthesizing random copolymer and block copolymers by the sequential growth of monomers from the substrate surface.
基金supported by the National Science Foundation(nos.CHE-1808829 and DMR 1809612)National Institutes of Health(no.R01DC014461)the United States,and the Gordon and Betty Moore Foundation.
文摘While self-assembly is relatively well-known and widely used to form hierarchical structures and thin film coatings,controlled assembly is less known and utilized.Our prior work has demonstrated the concept of controlled assembly of macromolecules such as star polymers[molecular weight(M_(w))∼383 kDa,hydrodynamic radius R∼13.8 nm]in droplets.This work extends this concept to smaller molecules,in this case,poly(ethylene glycol)bis-tetrazine(PEGbisTz,M_(w) 8.1 kDa,R∼1.5 nm).The key to controlled molecular assembly is to first deliver ultrasmall volumes(sub-fL)of solution containing PEG-bisTz to a substrate.The solvent evaporates rapidly due to the minute volume,thus forcing the assembly of solute,whose overall size and dimension are dictated by the initial liquid geometry and size.Using prepatterned surfaces,this work revealed that the initial liquid shape can be further tuned,and we could control the final assembly of solute such as PEGbisTz molecules.The degree of control was demonstrated by varying the micropatterns and delivery conditions.This work demonstrated the validity of controlled assembly for PEG-bisTz and enables three-dimensional(3D)nanoprinting of functional materials.The technology has promising applications in nanophotonics,nanoelectronics,nanocomposite materials,and tissue engineering.
