A Tutorial on the Mechanisms, Dynamics, and Control of Atomic Force Microscopes

Abramovitch, Daniel Y.; Andersson, Sean B.; Pao, Lucy Y.; Schitter, Georg

doi:10.1109/acc.2007.4282300

Cited by 185 publications

(128 citation statements)

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“…The controller signal is thus a direct estimate of the surface structure. PI-or PID-controllers are widely used in the feedback loop (Abramovitch et al, 2007). However, also other controller types like Proportional-Double-Integral (PII) or Proportional-Double-Integral-Derivative (PIID) controllers have been reported (Abramovitch et al, 2009).…”

Section: Atomic Force Microscope In Constant Force Modementioning

confidence: 99%

“…PI-or PID-controllers are widely used in the feedback loop (Abramovitch et al, 2007). However, also other controller types like Proportional-Double-Integral (PII) or Proportional-Double-Integral-Derivative (PIID) controllers have been reported (Abramovitch et al, 2009). Since the relation between the force acting on the cantilever and the tip-sample-distance is highly non-linear, the closed-loop configuration enables a reliable detection of the sample surface properties.…”

Section: Atomic Force Microscope In Constant Force Modementioning

confidence: 99%

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Compensation method in sensor technology: a system-based description

Schulz

Gerlach

Röbenack

2012

J. Sens. Sens. Syst.

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Abstract. In measurement science and engineering, the method of compensation plays a decisive role and is widely used in practical applications, in particular for sensors and measurement systems, where high accuracy is required. However, a general theoretical system description of this method with particular respect to figures of merit in sensor technology does not exist yet. Nevertheless, this is important for a real understanding of the system's structure and its properties and would facilitate prospective sensor design. Within this work, we provide a general system-based description and comparison of both the compensation and the deflection method. Based on a general sensor model and selected transfer functions, which cover most sensor types, important sensor properties like static deviations in sensitivity, long-term drift effects, response time, output signal characteristics as well as nonlinearities and hysteresis are studied in a systematic fashion for both measurement methods. In the case of a compensation method, the core sensor element is part of a controlled closed-loop system, leading to different system properties compared to an open-loop sensor operated in deflection method. The influence of linear standard controllers, which are widely used in industrial measurement and control systems, is studied with respect to the sensor properties. In the conclusions we will summarize which controller type is appropriate for the attainment of a specifically targeted sensor behavior.

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Section: Atomic Force Microscope In Constant Force Modementioning

confidence: 99%

Section: Atomic Force Microscope In Constant Force Modementioning

confidence: 99%

Compensation method in sensor technology: a system-based description

Schulz

Gerlach

Röbenack

2012

J. Sens. Sens. Syst.

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“…A complete description on the AFM operation and the corresponding modes can be found in Ref. 22. Figure 2(a) presents a section view of the rigid scanner where the counter z piezo can also be observed.…”

Section: Introductionmentioning

confidence: 99%

Compensator design for improved counterbalancing in high speed atomic force microscopy

Bozchalooi

Burns

Fantner

2011

Review of Scientific Instruments

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High speed atomic force microscopy can provide the possibility of many new scientific observations and applications ranging from nano-manufacturing to the study of biological processes. However, the limited imaging speed has been an imperative drawback of the atomic force microscopes. One of the main reasons behind this limitation is the excitation of the AFM dynamics at high scan speeds, severely undermining the reliability of the acquired images. In this research, we propose a piezo based, feedforward controlled, counter actuation mechanism to compensate for the excited out-ofplane scanner dynamics. For this purpose, the AFM controller output is properly filtered via a linear compensator and then applied to a counter actuating piezo. An effective algorithm for estimating the compensator parameters is developed. The information required for compensator design is extracted from the cantilever deflection signal, hence eliminating the need for any additional sensors. The proposed approach is implemented and experimentally evaluated on the dynamic response of a custom made AFM. It is further assessed by comparing the imaging performance of the AFM with and without the application of the proposed technique and in comparison with the conventional counterbalancing methodology. The experimental results substantiate the effectiveness of the method in significantly improving the imaging performance of AFM at high scan speeds.

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“…Topological information is typically derived from the corresponding motion of the vertical (z) actuator. 2 As a result, the rate of taking a single measurement is limited by the bandwidth of the z-piezo loop and a high overall frame rate comes at a cost in terms of the scanning size and the resolution. 3 Advanced hardware and specialized controller designs have been developed and integrated in a variety of commercial and research AFMs [4][5][6] to create high-speed AFM (HS-AFM) instruments that approach video-rate imaging.…”

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confidence: 99%

High speed atomic force microscopy enabled by a sample profile estimator

Huang

Andersson

2013

Applied Physics Letters

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In this paper, an estimation scheme for imaging in Atomic Force Microscopy (AFM) is presented which yields imaging rates well beyond the bandwidth of the vertical positioner and allows for high-speed AFM on a typical commercial instrument. The estimator can be applied to existing instruments with little to no hardware modification other than that needed to sample the cantilever signal. Experiments on a calibration sample as well as lambda DNA are performed to illustrate the effectiveness of this method. These show a greater than an order-of-magnitude improvement in the imaging rate. In atomic force microscopy (AFM), 1 a controller is used to tightly regulate the tip-sample interaction. Topological information is typically derived from the corresponding motion of the vertical (z) actuator. 2 As a result, the rate of taking a single measurement is limited by the bandwidth of the z-piezo loop and a high overall frame rate comes at a cost in terms of the scanning size and the resolution. 3 Advanced hardware and specialized controller designs have been developed and integrated in a variety of commercial and research AFMs 4-6 to create high-speed AFM (HS-AFM) instruments that approach video-rate imaging.Algorithmic approaches to HS-AFM seek to work with existing hardware and improve imaging rates by alternative approaches to selecting and acquiring measurements or through signal processing techniques to extract more information from poor signals. Because they require little to no hardware modification, they can be applied to existing AFMs to improve imaging rates as well as to HS-AFM instruments for even further gains. One example is our previous work for high-speed imaging of biopolymers and other string-like samples. 7 In this local raster scan, imaging time is reduced by using feedback to focus the measurements in the region of interest, namely, close to the biopolymer. Its effectiveness is due in part to the structure of the sample, and the approach is therefore limited to string-like samples. To allow for more general samples, in this work we present a fast estimation scheme that determines the sample profile at rates independent of the z-actuator loop. As a result, high-speed imaging can be achieved by integrating this signal with the conventional raster motion executed by any commercial AFM. It is also compatible with novel scanning trajectories, such as spiral scanning, 8 cycloids, 9 Lissajous figures, 10 and our local raster scan. 7 Driven by the requirements of imaging soft samples, we focus on intermittent (tapping) mode AFM.There are a few existing estimation-based approaches to AFM imaging. One relies on building an advanced controller based on robust control theory for the z-piezo. 11 By taking advantage of the structure of the controller, a signal was derived with a transfer function of 1 to the sample profile, implying an infinite bandwidth in the estimator. It is, however, only applicable to a particular instrument and relies on the specific controller. Given the fact that most commercial AFMs are equ...

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A Tutorial on the Mechanisms, Dynamics, and Control of Atomic Force Microscopes

Cited by 185 publications

References 100 publications

Compensation method in sensor technology: a system-based description

Compensation method in sensor technology: a system-based description

Compensator design for improved counterbalancing in high speed atomic force microscopy

High speed atomic force microscopy enabled by a sample profile estimator

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