Coaxial Atomic Force Microscope Tweezers

We demonstrate coaxial atomic force microscope (AFM) tweezers that can trap and place small objects using dielectrophoresis (DEP). An attractive force is generated at the tip of a coaxial AFM probe by applying a radio frequency voltage between the center conductor and a grounded shield; the origin of the force is found to be DEP by measuring the pull-off force vs. applied voltage. We show that the coaxial AFM tweezers (CAT) can perform three dimensional assembly by picking up a specified silica microsphere, imaging with the microsphere at the end of the tip, and placing it at a target destination.Comment: 9 pages, 3 figures, in review at Applied Physics Letter

Scanned-cantilever atomic force microscope

We have developed a 3.6 µm scan range atomic force microscope that scans the cantilever instead of the sample, while the optical-lever detection apparatus remains stationary. The design permits simpler, more adaptable sample mounting, and generally improves ease of use. Software workarounds alleviate the minor effects of spurious signal variations that arise as a result of scanning the cantilever. The performance of the microscope matches that of scanned-sample instruments

Fiber-top atomic force microscope

We present the implementation of an atomic force microscope (AFM) based on fiber-top design. Our results demonstrate that the performances of fiber-top AFMs in contact mode are comparable to those of similar commercially available instruments. Our device thus represents an interesting\ud alternative to existing AFMs, particularly for applications outside specialized research laboratories, where a compact, user-friendly, and versatile tool might often be preferred

Atomic Force Microscope

The scanning tunneling microscope is proposed as a method to measure forces as small as 10−18 N. As one application for this concept, we introduce a new type of microscope capable of investigating surfaces of insulators on an atomic scale. The atomic force microscope is a combination of the principles of the scanning tunneling microscope and the stylus profilometer. It incorporates a probe that does not damage the surface. Our preliminary results in air demonstrate a lateral resolution of 30 ÅA and a vertical resolution less than 1 Å

Imaging spectroscopy with the atomic force microscope

Force curve imaging spectroscopy involves acquiring a force-distance curve at each pixel of an atomic force microscope image. Processing of the resulting data yields images of sample hardness and tip-sample adhesion. These images resemble Z modulation images and the sum of forward and reverse friction images, respectively, and like them exhibit a number of potentially misleading contrast mechanisms. In particular, XY tip motion has a pronounced effect on hardness images and the meniscus force on adhesion images

Development and testing of a XYZ scanner for atomic force microscope

Atomic force microscopy (AFM) is a widely used tool in nano measurement and manipulation techniques. However, a traditional AFM system suffers from the limitation of slow scanning rate, due to the low dynamic performance of piezoelectric positioners. As an important part of AFM system, scanner will have a significant impact the result of the scanning imaging and operation. It is well know that high-speed operation of an AFM are increasingly required, and it is also a challenge for the researchers. In this paper, we proposed a parallel kinematic high-speed piezoelectric actuator (PZT) XYZ scanner. The design is aimed at achieving high resonance frequencies and low cross-coupling. The developed stage consists of a parallel kinematic XY stage and a Z stage. The Z stage is mounted on the central moving platform of the XY stage. To achieve the design objective, several parallel leaf flexure hinge mechanisms, arranging symmetrically around the central moving platform of the XY stage, are utilized to provide large stiffness and reduce cross-coupling. For the Z stage, a symmetrical leaf flexure parallelogram mechanism is adopted to achieve high resonance frequencies and decoupling. Then, finite element analysis (FEA) is utilized to validate the characteristics of the XYZ scanner. Finally, extensive experiments are conducted, demonstrating feasibility of the proposed scanner

Models for quantitative charge imaging by atomic force microscopy

Two models are presented for quantitative charge imaging with an atomic-force microscope. The first is appropriate for noncontact mode and the second for intermittent contact (tapping) mode imaging. Different forms for the contact force are used to demonstrate that quantitative charge imaging is possible without precise knowledge of the contact interaction. From the models, estimates of the best charge sensitivity of an unbiased standard atomic-force microscope cantilever are found to be on the order of a few electrons

Development of a XYZ scanner for home-made atomic force microscope based on FPAA control

Atomic force microscopy (AFM) is one of the useful tools in the fields of nanoscale measurement and manipulation. High speed scanning is one of the crucial requirements for live cell imaging and soft matter characterization. The scanning speed is limited by the bandwidth of the AFM’s detection and actuation components. Generally, the bandwidth of a traditional scanner is too low to conduct the live cell imaging. This paper presents a simple and integrated compact home-made AFM for high speed imaging. To improve the bandwidth of the scanner, a parallel kinematics mechanism driven by piezoelectric actuators (PZTs) is proposed for the fast positioning in the X, Y and Z directions. The mechanical design optimization, modeling and analysis, and experimental testing have been conducted to validate the performance of the proposed scanner. A number of experimental results showed that the developed scanner has the capability for broad bandwidth with low coupling errors in the actuation directions. A hybrid control strategy including feedforward and feedback loops has been designed to significantly improve the dynamic tracking performance of the scanner and a field programmable analog array (FPAA) system is utilized to implement the control algorithm for excellent and stable tracking capability. Further, a number of high speed measurements have been conducted to verify the performance of the developed AFM