Menu
AFM Design Overview
An overview video of a high-speed AFM system developed at MRL for video rate imaging.
AFM Software Architecture
LabVIEW software for AFM imaging congrol and visualization
AFM Imaging Demonstration
Optical view of AFM cantilever probe conducting imaging with video showing real-time imaging of deposition
- Microscopy instruments are important in nanotechnology research for imaging of nanoscale phenomena. Among such tools is the atomic force microscope (AFM) for nanoscale imaging and surface characterization. An AFM scans a micro-cantilever over the sample surface to measure various quantities from the probe-sample interaction. With high-speed imaging, dynamic processes can be visualized to improve fundamental understanding of microscopic interactions. Scientists can use videos, in addition to images, to observe and compare experimental data with theoretical predictions, and verify models without speculating about intermediate dynamics. However, conventional AFMs have limited throughput that allow for static imaging only and require transparent working environments.
- The contributions of this work remove such AFM restrictions and enable advanced visualization capabilities. Example applications include visualizing chemical reactions and biological responses in their native environments. To this end, the thesis addresses four main AFM limitations. These are (i) increase the low imaging throughput to be compatible for higher temporal resolution imaging, (ii) remove the transparency requirement, for AFMs that use optical beam deflection sensing, and enable imaging in harsh opaque liquids, (iii) establish automation algorithms to reduce operational overheads associated with experiment setup and controller tuning, and (iv) introduce custom design modifications resulting in affordable AFMs for engineering education.
These new capabilities are primarily enabled with the development of new subsystems. The key components include nano-positioners, cantilever probes, and control algorithms. New generation AFM nano-positioners are designed with high-speed, large-range or low-cost characteristics for different scanning needs. Coated active cantilever probes are developed for AFM imaging in specialized opaque environments. Multiple algorithms for scanner control, automatic tuning, and image formation are investigated to improve AFM imaging performance. Additional developments to support AFM imaging include high-bandwidth driver electronics, optical systems with vision-based automation, and software implementation for AFM big data processing. Three AFM systems are integrated using these new subsystems for different applications. They include a versatile sample scan AFM for overview-and-zoom imaging in air and liquids, a multi-layer stacked scanner AFM for high-speed and large-range imaging in air, and a low-cost active probe AFM for engineering education. AFM images and videos at 20 frames per second are taken in various environments to verify the new capabilities. These developments have broader impacts in the fields of precision instrumentation, nano-fabrication, and nano-scale process video-rate visualization.
- The main susbsystem level contributions involved in this work include:
- 1) high-speed and large-range AFM nano-positioner design
- 2) imaging algorithms for scanner control and sampling
- 3) optical system for small probes with automation
- 4) coated active cantilever probes for opaque liquid operation
- 5) high-bandwidth driver and signal conditioning electronics
- 6) software implementation of high-speed data processing
- 7) AFM system integration for dynamic process visualization.
- The AFM development extends the capabilities of current AFM systems in various aspects. The research also has broader impacts in the fields of precision instrumentation, nano-fabrication and chemical or biological process visualization. Continuing work of this project for fundamental research applications are currently in progress.
Publications
2021
19.
Fangzhou Xia; James Quigley; Xiaotong Zhang; Chen Yang; Yi Wang; Kamal Youcef-Toumi
A modular low-cost atomic force microscope for precision mechatronics education Journal Article
In: Mechatronics, vol. 76, pp. 102550, 2021, ISSN: 0957-4158.
@article{MRL_AFM_Low_cost_AFM,
title = {A modular low-cost atomic force microscope for precision mechatronics education},
author = {Fangzhou Xia and James Quigley and Xiaotong Zhang and Chen Yang and Yi Wang and Kamal Youcef-Toumi},
url = {https://www.sciencedirect.com/science/article/pii/S0957415821000441},
doi = {https://doi.org/10.1016/j.mechatronics.2021.102550},
issn = {0957-4158},
year = {2021},
date = {2021-04-15},
journal = {Mechatronics},
volume = {76},
pages = {102550},
publisher = {ScienceDirect},
abstract = {Precision mechatronics and nanotechnology communities can both benefit from a course centered around an Atomic Force Microscope (AFM). Developing an AFM can provide precision mechatronics engineers with a valuable multidisciplinary hands-on training experience. In return, such expertise can be applied to the design and implementation of new precision instruments, which helps nanotechnology researchers make new scientific discoveries. However, existing AFMs are not suitable for mechatronics education due to their different original design intentions. Therefore, we address this challenge by developing an AFM intended for precision mechatronics education. This paper presents the design and implementation of an educational AFM and its corresponding precision mechatronics class. The modular educational AFM is low-cost (≤$4,000) and easy to operate. The cost reduction is enabled by new subsystem development of a buzzer-actuated scanner and demodulation electronics designed to interface with a myRIO data acquisition system. Moreover, the use of an active cantilever probe with piezoresistive sensing and thermomechanical actuation significantly reduced experiment setup overhead with improved operational safety. In the end, the developed AFM capabilities are demonstrated with imaging results. The paper also showcases the course design centered around selected subsystems. The new AFM design allows scientific-method-based learning, maximizes utilization of existing resources, and offers potential subsystem upgrades for high-end research applications. The presented instrument and course can help connect members of both the AFM and the mechatronics communities to further develop advanced techniques for new applications.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Precision mechatronics and nanotechnology communities can both benefit from a course centered around an Atomic Force Microscope (AFM). Developing an AFM can provide precision mechatronics engineers with a valuable multidisciplinary hands-on training experience. In return, such expertise can be applied to the design and implementation of new precision instruments, which helps nanotechnology researchers make new scientific discoveries. However, existing AFMs are not suitable for mechatronics education due to their different original design intentions. Therefore, we address this challenge by developing an AFM intended for precision mechatronics education. This paper presents the design and implementation of an educational AFM and its corresponding precision mechatronics class. The modular educational AFM is low-cost (≤$4,000) and easy to operate. The cost reduction is enabled by new subsystem development of a buzzer-actuated scanner and demodulation electronics designed to interface with a myRIO data acquisition system. Moreover, the use of an active cantilever probe with piezoresistive sensing and thermomechanical actuation significantly reduced experiment setup overhead with improved operational safety. In the end, the developed AFM capabilities are demonstrated with imaging results. The paper also showcases the course design centered around selected subsystems. The new AFM design allows scientific-method-based learning, maximizes utilization of existing resources, and offers potential subsystem upgrades for high-end research applications. The presented instrument and course can help connect members of both the AFM and the mechatronics communities to further develop advanced techniques for new applications.
2020
18.
Fangzhou Xia; Chen Yang; Yi Wang; Kamal Youcef-Toumi
Model and Controller Design for High-speed Atomic Force Microscope Imaging and Autotuning Proceedings Article
In: 2020 ASPE Spring Topical Meeting on Design and Control of Precision Mechatronic Systems, pp. 99–104, ASPE ASPE, 2020.
@inproceedings{MRL_AFM_Imaging_Autotuning,
title = {Model and Controller Design for High-speed Atomic Force Microscope Imaging and Autotuning},
author = {Fangzhou Xia and Chen Yang and Yi Wang and Kamal Youcef-Toumi},
url = {https://www.dropbox.com/s/vekbaco9oq3kkuu/2020%20Spring%20Topical%20Design%20and%20Controls%20Proceedings%20revised%20DT.pdf?dl=0},
year = {2020},
date = {2020-05-08},
booktitle = {2020 ASPE Spring Topical Meeting on Design and Control of Precision Mechatronic Systems},
pages = {99--104},
publisher = {ASPE},
organization = {ASPE},
abstract = {Atomic Force Microscope (AFM) is a powerful nano-scale surface measurement instrument. However, significant operator experience is needed for successful imaging. Parameters of the PID controller for probe deflection or oscillation regulation are tuned by the operator based on visual inspection of the trace and retrace tracking performance. With the development of high-speed AFM and for the purpose of operation overhead reduction, automated parameter tuning of the controller is needed. In this work, we propose a unified framework with various control and image generation improvement methods for contact mode AFM, starting first with an automated PID controller tuning and scan speed adjustment method. Second, we discuss three methods to improve imaging performance including location-based sampling, line-based feedforward and error-corrected image generation. Third, in cases where topography variation and material properties are non-uniform across the sample surface, a single neuron PID is designed for model-free adaptive tracking. With a lumped parameter AFM model created in Matlab Simulink, the proposed algorithms are evaluated in simulation to demonstrate their effectiveness. The methods are summarized into a unified framework where methods can be automatically selected after initialization to improve AFM imaging performance.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
Atomic Force Microscope (AFM) is a powerful nano-scale surface measurement instrument. However, significant operator experience is needed for successful imaging. Parameters of the PID controller for probe deflection or oscillation regulation are tuned by the operator based on visual inspection of the trace and retrace tracking performance. With the development of high-speed AFM and for the purpose of operation overhead reduction, automated parameter tuning of the controller is needed. In this work, we propose a unified framework with various control and image generation improvement methods for contact mode AFM, starting first with an automated PID controller tuning and scan speed adjustment method. Second, we discuss three methods to improve imaging performance including location-based sampling, line-based feedforward and error-corrected image generation. Third, in cases where topography variation and material properties are non-uniform across the sample surface, a single neuron PID is designed for model-free adaptive tracking. With a lumped parameter AFM model created in Matlab Simulink, the proposed algorithms are evaluated in simulation to demonstrate their effectiveness. The methods are summarized into a unified framework where methods can be automatically selected after initialization to improve AFM imaging performance.
17.
Chen Yang; Nicolas Verbeek; Fangzhou Xia; Yi Wang; Kamal Youcef-Toumi
Modeling and Control of Piezoelectric Hysteresis: A Polynomial-Based Fractional Order Disturbance Compensation Approach Journal Article
In: IEEE Transactions on Industrial Electronics, 2020, ISSN: 1557-9948.
@article{MRL_AFM_Charge_Controller_PBFODC,
title = {Modeling and Control of Piezoelectric Hysteresis: A Polynomial-Based Fractional Order Disturbance Compensation Approach},
author = {Chen Yang and Nicolas Verbeek and Fangzhou Xia and Yi Wang and Kamal Youcef-Toumi},
url = {https://ieeexplore.ieee.org/document/9027124},
doi = {10.1109/TIE.2020.2977567},
issn = {1557-9948},
year = {2020},
date = {2020-03-06},
journal = {IEEE Transactions on Industrial Electronics},
publisher = {IEEE},
abstract = {Piezoelectric hysteresis is a critical issue that significantly degrades the motion accuracy of piezo-actuated nanopositioners. Such an issue is difficult to be precisely modeled and compensated for, primarily due to its asymmetric, rate and input amplitude dependent characteristics. This paper proposes a novel method to deal with this challenge. Specifically, a polynomial-based fractional order disturbance model is proposed to accommodate and characterize the complex hysteresis effect. In this model, the rate dependency is captured by a general method of implementing curve fitting in Bode magnitude plot. The inverse model for control purposes is immediately available from the original one. The proposed method does not require expensive computational resources. In fact, this paper shows that this controller can be easily implemented in an analog manner, which brings the advantages of high-bandwidth and low-cost. Extensive modeling and tracking experiments are carried out to demonstrate the effectiveness of the proposed method. It is shown that the piezoelectric hysteresis nonlinearity can be significantly suppressed over a wide bandwidth.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Piezoelectric hysteresis is a critical issue that significantly degrades the motion accuracy of piezo-actuated nanopositioners. Such an issue is difficult to be precisely modeled and compensated for, primarily due to its asymmetric, rate and input amplitude dependent characteristics. This paper proposes a novel method to deal with this challenge. Specifically, a polynomial-based fractional order disturbance model is proposed to accommodate and characterize the complex hysteresis effect. In this model, the rate dependency is captured by a general method of implementing curve fitting in Bode magnitude plot. The inverse model for control purposes is immediately available from the original one. The proposed method does not require expensive computational resources. In fact, this paper shows that this controller can be easily implemented in an analog manner, which brings the advantages of high-bandwidth and low-cost. Extensive modeling and tracking experiments are carried out to demonstrate the effectiveness of the proposed method. It is shown that the piezoelectric hysteresis nonlinearity can be significantly suppressed over a wide bandwidth.
2019
16.
Fangzhou Xia; Chen Yang; Yi Wang; Kamal Youcef-Toumi
Bandwidth Based Repetitive Controller Design for a Modular Multi-actuated AFM Scanner Proceedings Article
In: 2019 American Control Conference (ACC), pp. 3776–3781, IEEE IEEE, 2019.
@inproceedings{MRL_AFM_Bandwidth_Based_Repetitive_Control,
title = {Bandwidth Based Repetitive Controller Design for a Modular Multi-actuated AFM Scanner},
author = {Fangzhou Xia and Chen Yang and Yi Wang and Kamal Youcef-Toumi},
url = {https://ieeexplore.ieee.org/document/8814642},
doi = {10.23919/ACC.2019.8814642},
year = {2019},
date = {2019-08-29},
booktitle = {2019 American Control Conference (ACC)},
pages = {3776--3781},
publisher = {IEEE},
organization = {IEEE},
abstract = {High-Speed Atomic Force Micrscopy (HSAFM) enables visualization of dynamic processes and helps with understanding of fundamental behaviors at the nano-scale. Ideally, the HSAFM video frames should have high fidelity, high resolution, and a wide scanning range. Unfortunately, it is very difficult for scanners to simultaneously achieve high scanning bandwidth and large range. Since the first bending mode of large piezos is a major limiting factor, we propose an alternative design by stacking multiple short range piezo actuators. This approach allows significant increase of scanner bandwidth (over 20 kHz) while maintaining large travel range (over 20 μm). The modular design also facilitates the easy adjustment of scanner travel range. In this paper, we first discuss the design and assembly of this scanner. We then present the modeling and control of this multi-actuated scanner. A comparative study is then given on the performance of different controllers. These include a PID controller, a LQR based controller and a bandwidth based repetitive controller. The proposed algorithm provides significant improvement in tracking performance when utilized with the scanner using optimized input trajectories.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
High-Speed Atomic Force Micrscopy (HSAFM) enables visualization of dynamic processes and helps with understanding of fundamental behaviors at the nano-scale. Ideally, the HSAFM video frames should have high fidelity, high resolution, and a wide scanning range. Unfortunately, it is very difficult for scanners to simultaneously achieve high scanning bandwidth and large range. Since the first bending mode of large piezos is a major limiting factor, we propose an alternative design by stacking multiple short range piezo actuators. This approach allows significant increase of scanner bandwidth (over 20 kHz) while maintaining large travel range (over 20 μm). The modular design also facilitates the easy adjustment of scanner travel range. In this paper, we first discuss the design and assembly of this scanner. We then present the modeling and control of this multi-actuated scanner. A comparative study is then given on the performance of different controllers. These include a PID controller, a LQR based controller and a bandwidth based repetitive controller. The proposed algorithm provides significant improvement in tracking performance when utilized with the scanner using optimized input trajectories.
15.
Chen Yang; Fangzhou Xia; Yi Wang; Stephen Truncale; Kamal Youcef-Toumi
Design and Control of a Multi-Actuated Nanopositioning Stage with Stacked Structure Proceedings Article
In: 2019 American Control Conference (ACC), pp. 3782–3788, IEEE IEEE, 2019, ISBN: 978-1-5386-7926-5.
@inproceedings{MRL_AFM_Stacked_Nanopositioner,
title = {Design and Control of a Multi-Actuated Nanopositioning Stage with Stacked Structure},
author = {Chen Yang and Fangzhou Xia and Yi Wang and Stephen Truncale and Kamal Youcef-Toumi},
url = {https://ieeexplore.ieee.org/document/8815299},
doi = {10.23919/ACC.2019.8815299},
isbn = {978-1-5386-7926-5},
year = {2019},
date = {2019-08-29},
booktitle = {2019 American Control Conference (ACC)},
pages = {3782--3788},
publisher = {IEEE},
organization = {IEEE},
abstract = {A novel multi-actuated nanopositioning stage with stacked structure has been developed. The aim is to achieve both high bandwidth and large motion range. Symmetric flexures are designed to obtain equal stiffness along any direction in the lateral plane. With this design, the lateral stiffness and corresponding bending mode resonance frequency can be optimized. Both analytical model and finite element analysis are employed to predict the dominant resonance frequency. Experimental results indicate that the dominant resonance of nanopositioner is at 28.2 kHz, with a motion range of 16.5J.1m. A disturbance-observer-based controller is implemented to suppress the hysteretic nonlinearity. The new design and control system enable high-bandwidth and high-precision nanopositioning up to 2 kHz.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
A novel multi-actuated nanopositioning stage with stacked structure has been developed. The aim is to achieve both high bandwidth and large motion range. Symmetric flexures are designed to obtain equal stiffness along any direction in the lateral plane. With this design, the lateral stiffness and corresponding bending mode resonance frequency can be optimized. Both analytical model and finite element analysis are employed to predict the dominant resonance frequency. Experimental results indicate that the dominant resonance of nanopositioner is at 28.2 kHz, with a motion range of 16.5J.1m. A disturbance-observer-based controller is implemented to suppress the hysteretic nonlinearity. The new design and control system enable high-bandwidth and high-precision nanopositioning up to 2 kHz.
14.
Fangzhou Xia; Chen Yang; Yi Wang; Kamal Youcef-Toumi; Christoph Reuter; Tzvetan Ivanov; Mathias Holz; Ivo W Rangelow
Lights Out! Nano-Scale Topography Imaging of Sample Surface in Opaque Liquid Environments with Coated Active Cantilever Probes Journal Article
In: Nanomaterials, vol. 9, no. 7, pp. 1013, 2019.
@article{MRL_AFM_coated_probe,
title = {Lights Out! Nano-Scale Topography Imaging of Sample Surface in Opaque Liquid Environments with Coated Active Cantilever Probes},
author = {Fangzhou Xia and Chen Yang and Yi Wang and Kamal Youcef-Toumi and Christoph Reuter and Tzvetan Ivanov and Mathias Holz and Ivo W Rangelow},
url = {https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6669515/},
doi = {10.3390/nano9071013},
year = {2019},
date = {2019-07-09},
journal = {Nanomaterials},
volume = {9},
number = {7},
pages = {1013},
publisher = {Multidisciplinary Digital Publishing Institute},
abstract = {Atomic force microscopy is a powerful topography imaging method used widely in nanoscale metrology and manipulation. A conventional Atomic Force Microscope (AFM) utilizes an optical lever system typically composed of a laser source, lenses and a four quadrant photodetector to amplify and measure the deflection of the cantilever probe. This optical method for deflection sensing limits the capability of AFM to obtaining images in transparent environments only. In addition, tapping mode imaging in liquid environments with transparent sample chamber can be difficult for laser-probe alignment due to multiple different refraction indices of materials. Spurious structure resonance can be excited from piezo actuator excitation. Photothermal actuation resolves the resonance confusion but makes optical setup more complicated. In this paper, we present the design and fabrication method of coated active scanning probes with piezoresistive deflection sensing, thermomechanical actuation and thin photoresist polymer surface coating. The newly developed probes are capable of conducting topography imaging in opaque liquids without the need of an optical system. The selected coating can withstand harsh chemical environments with high acidity (e.g., 35% sulfuric acid). The probes are operated in various opaque liquid environments with a custom designed AFM system to demonstrate the imaging performance. The development of coated active probes opens up possibilities for observing samples in their native environments.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Atomic force microscopy is a powerful topography imaging method used widely in nanoscale metrology and manipulation. A conventional Atomic Force Microscope (AFM) utilizes an optical lever system typically composed of a laser source, lenses and a four quadrant photodetector to amplify and measure the deflection of the cantilever probe. This optical method for deflection sensing limits the capability of AFM to obtaining images in transparent environments only. In addition, tapping mode imaging in liquid environments with transparent sample chamber can be difficult for laser-probe alignment due to multiple different refraction indices of materials. Spurious structure resonance can be excited from piezo actuator excitation. Photothermal actuation resolves the resonance confusion but makes optical setup more complicated. In this paper, we present the design and fabrication method of coated active scanning probes with piezoresistive deflection sensing, thermomechanical actuation and thin photoresist polymer surface coating. The newly developed probes are capable of conducting topography imaging in opaque liquids without the need of an optical system. The selected coating can withstand harsh chemical environments with high acidity (e.g., 35% sulfuric acid). The probes are operated in various opaque liquid environments with a custom designed AFM system to demonstrate the imaging performance. The development of coated active probes opens up possibilities for observing samples in their native environments.
2018
13.
Chen Yang; Changle Li; Fangzhou Xia; Yanhe Zhu; Jie Zhao; Kamal Youcef-Toumi
Charge Controller With Decoupled and Self-Compensating Configurations for Linear Operation of Piezoelectric Actuators in a Wide Bandwidth Journal Article
In: IEEE Transactions on Industrial Electronics, vol. 66, no. 7, pp. 5392–5402, 2018.
@article{MRL_AFM_Charge_Controller_Self_Compensating,
title = {Charge Controller With Decoupled and Self-Compensating Configurations for Linear Operation of Piezoelectric Actuators in a Wide Bandwidth},
author = {Chen Yang and Changle Li and Fangzhou Xia and Yanhe Zhu and Jie Zhao and Kamal Youcef-Toumi},
url = {https://ieeexplore.ieee.org/document/8466119},
doi = {10.1109/TIE.2018.2868321},
year = {2018},
date = {2018-09-14},
journal = {IEEE Transactions on Industrial Electronics},
volume = {66},
number = {7},
pages = {5392--5402},
publisher = {IEEE},
abstract = {Charge control is a well-known sensorless approach to operate piezoelectric actuators, which has been proposed for more than 30 years. However, it is rarely used in industry because the implemented controllers suffer from the issues of limited low-frequency performance, long settling time, floating-load, and loss of stroke, etc. In this paper, a novel controller circuit dedicated to overcome these issues is presented. In the proposed scheme, a grounded-load charge controller with decoupled configuration is developed, which separates high-frequency and low-frequency paths, thus achieving arbitrarily low transition frequency without increasing the settling time. Based on this, a self-compensating configuration is further proposed and integrated into the controller circuit, which makes full use of controller output to improve its own control performance at low frequencies. Experimental results show that the presented charge controller can effectively reduce more than 88% of the hysteretic nonlinearity even when operating close to the transition frequency. To demonstrate its practical value, we then integrate it into a custom-designed high-speed atomic force microscope system. By comparing images obtained from using voltage drive and charge controller, it is clear that the piezoelectric hysteresis has been significantly reduced in a wide bandwidth.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Charge control is a well-known sensorless approach to operate piezoelectric actuators, which has been proposed for more than 30 years. However, it is rarely used in industry because the implemented controllers suffer from the issues of limited low-frequency performance, long settling time, floating-load, and loss of stroke, etc. In this paper, a novel controller circuit dedicated to overcome these issues is presented. In the proposed scheme, a grounded-load charge controller with decoupled configuration is developed, which separates high-frequency and low-frequency paths, thus achieving arbitrarily low transition frequency without increasing the settling time. Based on this, a self-compensating configuration is further proposed and integrated into the controller circuit, which makes full use of controller output to improve its own control performance at low frequencies. Experimental results show that the presented charge controller can effectively reduce more than 88% of the hysteretic nonlinearity even when operating close to the transition frequency. To demonstrate its practical value, we then integrate it into a custom-designed high-speed atomic force microscope system. By comparing images obtained from using voltage drive and charge controller, it is clear that the piezoelectric hysteresis has been significantly reduced in a wide bandwidth.
12.
Fangzhou Xia; Stephen Truncale; Yi Wang; Kamal Youcef-Toumi
Design and Control of a Multi-actuated High-bandwidth and Large-range Scanner for Atomic Force Microscopy Proceedings Article
In: 2018 Annual American Control Conference (ACC), pp. 4330–4335, IEEE IEEE, 2018.
@inproceedings{MRL_AFM_Dual_Actuated_Scanner,
title = {Design and Control of a Multi-actuated High-bandwidth and Large-range Scanner for Atomic Force Microscopy},
author = {Fangzhou Xia and Stephen Truncale and Yi Wang and Kamal Youcef-Toumi},
url = {https://ieeexplore.ieee.org/document/8431801},
doi = {10.23919/ACC.2018.8431801},
year = {2018},
date = {2018-08-16},
booktitle = {2018 Annual American Control Conference (ACC)},
pages = {4330--4335},
publisher = {IEEE},
organization = {IEEE},
abstract = {Atomic force microscopes (AFMs) with high-speed and large-range capabilities open up possibilities for many new applications. It is desirable to have a large scanning range along with zooming ability to obtain high resolution and high frame-rate imaging. Such capabilities will increase the imaging throughput and allow more sophisticated observations at the nanoscale. Unfortunately, in-plane scanning of conventional piezo tube scanners typically covers a large range of hundreds of microns but has limited bandwidth up to several hundred Hertz. The main focus of this paper is the multi-actuated piezo scanner design and control algorithm to achieve high-speed tracking. Three design strategies for structure bandwidth and operational range consideration are presented and evaluated. The non-linear hysteresis effect of the piezo actuators is modeled using the Preisach hysteresis model. PID control, iterative learning control and repetitive control strategies were investigated in simulation. Based on the controllers performance, the repetitive controller is implemented on a high-speed FPGA device and experimentally verified. The new AFM scanner design is capable of 10 kHz tracking at 3 μm range and 200 Hz tracking at 100 μm range.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
Atomic force microscopes (AFMs) with high-speed and large-range capabilities open up possibilities for many new applications. It is desirable to have a large scanning range along with zooming ability to obtain high resolution and high frame-rate imaging. Such capabilities will increase the imaging throughput and allow more sophisticated observations at the nanoscale. Unfortunately, in-plane scanning of conventional piezo tube scanners typically covers a large range of hundreds of microns but has limited bandwidth up to several hundred Hertz. The main focus of this paper is the multi-actuated piezo scanner design and control algorithm to achieve high-speed tracking. Three design strategies for structure bandwidth and operational range consideration are presented and evaluated. The non-linear hysteresis effect of the piezo actuators is modeled using the Preisach hysteresis model. PID control, iterative learning control and repetitive control strategies were investigated in simulation. Based on the controllers performance, the repetitive controller is implemented on a high-speed FPGA device and experimentally verified. The new AFM scanner design is capable of 10 kHz tracking at 3 μm range and 200 Hz tracking at 100 μm range.
2017
11.
Ivo W Rangelow; Tzvetan Ivanov; Ahmad Ahmad; Marcus Kaestner; Claudia Lenk; Iman Soltani Bozchalooi; Fangzhou Xia; Kamal Youcef-Toumi; Mathias Holz; Alexander Reum
Review Article: Active scanning probes: A versatile toolkit for fast imaging and emerging nanofabrication Journal Article
In: Journal of Vacuum Science & Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena, vol. 35, no. 6, pp. 06G101, 2017.
@article{MRL_AFM_active_probe_review,
title = {Review Article: Active scanning probes: A versatile toolkit for fast imaging and emerging nanofabrication},
author = {Ivo W Rangelow and Tzvetan Ivanov and Ahmad Ahmad and Marcus Kaestner and Claudia Lenk and Iman Soltani Bozchalooi and Fangzhou Xia and Kamal Youcef-Toumi and Mathias Holz and Alexander Reum},
url = {https://avs.scitation.org/doi/full/10.1116/1.4992073},
doi = {10.1116/1.4992073},
year = {2017},
date = {2017-11-03},
journal = {Journal of Vacuum Science & Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena},
volume = {35},
number = {6},
pages = {06G101},
publisher = {American Vacuum Society},
abstract = {With the recent advances in the field of nanotechnology, measurement and manipulation requirements at the nanoscale have become more stringent than ever before. In atomic force microscopy, high-speed performance alone is not sufficient without considerations of other aspects of the measurement task, such as the feature aspect ratio, required range, or acceptable probe-sample interaction forces. In this paper, the authors discuss these requirements and the research directions that provide the highest potential in meeting them. The authors elaborate on the efforts toward the downsizing of self-sensed and self-actuated probes as well as on upscaling by active cantilever arrays. The authors present the fabrication process of active probes along with the tip customizations carriedout targeting specific application fields. As promising application in scope of nanofabrication, field emission scanning probe lithography is introduced. The authors further discuss their control and design approach. Here, microactuators, e.g., multilayer microcantilevers, and macroactuators, e.g., flexure scanners, are combined in order to simultaneously meet both the range and speed requirements of a new generation of scanning probe microscopes.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
With the recent advances in the field of nanotechnology, measurement and manipulation requirements at the nanoscale have become more stringent than ever before. In atomic force microscopy, high-speed performance alone is not sufficient without considerations of other aspects of the measurement task, such as the feature aspect ratio, required range, or acceptable probe-sample interaction forces. In this paper, the authors discuss these requirements and the research directions that provide the highest potential in meeting them. The authors elaborate on the efforts toward the downsizing of self-sensed and self-actuated probes as well as on upscaling by active cantilever arrays. The authors present the fabrication process of active probes along with the tip customizations carriedout targeting specific application fields. As promising application in scope of nanofabrication, field emission scanning probe lithography is introduced. The authors further discuss their control and design approach. Here, microactuators, e.g., multilayer microcantilevers, and macroactuators, e.g., flexure scanners, are combined in order to simultaneously meet both the range and speed requirements of a new generation of scanning probe microscopes.
10.
Fangzhou Xia; Iman Soltani Bozchalooi; Kamal Youcef-Toumi
Induced Vibration Contact Detection for Minimizing Cantilever Tip-Sample Interaction Forces in Jumping Mode Atomic Force Microscopy Proceedings Article
In: 2017 American Control Conference (ACC), pp. 4141–4146, IEEE IEEE, 2017, ISBN: 978-1-5090-5992-8.
@inproceedings{MRL_AFM_IVCD,
title = {Induced Vibration Contact Detection for Minimizing Cantilever Tip-Sample Interaction Forces in Jumping Mode Atomic Force Microscopy},
author = {Fangzhou Xia and Iman Soltani Bozchalooi and Kamal Youcef-Toumi},
url = {https://ieeexplore.ieee.org/document/7963591},
doi = {10.23919/ACC.2017.7963591},
isbn = {978-1-5090-5992-8},
year = {2017},
date = {2017-07-03},
booktitle = {2017 American Control Conference (ACC)},
pages = {4141--4146},
publisher = {IEEE},
organization = {IEEE},
abstract = {Minimizing tip-sample interaction force is crucial for the performance of atomic force microscopes when imaging delicate samples. Conventional methods based on jumping mode such as peak force tapping require a prescribed maximum interaction force to detect tip-sample contact. However, due to the presence of drag forces (in aqueous environments), noises and cantilever dynamics, the minimal detectable peak force can be large. This results in large tip-sample interaction forces and hence sample damage. To minimize this force, we propose a method based on induction of surface or probe vibrations to detect contact between cantilever probe tip and sample substrate. To illustrate the effectiveness of the method, we report experimental results for contact detection on a PS-LDPE-12M polymer sample. A topography tracking control algorithm based on the proposed contact detection scheme is also presented.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
Minimizing tip-sample interaction force is crucial for the performance of atomic force microscopes when imaging delicate samples. Conventional methods based on jumping mode such as peak force tapping require a prescribed maximum interaction force to detect tip-sample contact. However, due to the presence of drag forces (in aqueous environments), noises and cantilever dynamics, the minimal detectable peak force can be large. This results in large tip-sample interaction forces and hence sample damage. To minimize this force, we propose a method based on induction of surface or probe vibrations to detect contact between cantilever probe tip and sample substrate. To illustrate the effectiveness of the method, we report experimental results for contact detection on a PS-LDPE-12M polymer sample. A topography tracking control algorithm based on the proposed contact detection scheme is also presented.
2016
9.
Iman Soltani Bozchalooi; Andrew Careaga Houck; Jwaher M. AlGhamdi; Kamal Youcef-Toumi
Design and control of multi-actuated atomic force microscope for large-range and high-speed imaging Journal Article
In: vol. 160, pp. 213 - 224, 2016, ISSN: 0304-3991.
@article{MRL_AFM_LRHS_imaging,
title = {Design and control of multi-actuated atomic force microscope for large-range and high-speed imaging},
author = {Iman Soltani Bozchalooi and Andrew Careaga Houck and Jwaher M. AlGhamdi and Kamal Youcef-Toumi},
url = {http://www.sciencedirect.com/science/article/pii/S0304399115300528 https://www.youtube.com/watch?v=PQ-zE6wA61c},
doi = {https://doi.org/10.1016/j.ultramic.2015.10.016},
issn = {0304-3991},
year = {2016},
date = {2016-01-01},
volume = {160},
pages = {213 - 224},
abstract = {This paper presents the design and control of a high-speed and large-range atomic force microscopy (AFM). A multi-actuation scheme is proposed where several nano-positioners cooperate to achieve the range and speed requirements. A simple data-based control design methodology is presented to effectively operate the AFM scanner components. The proposed controllers compensate for the coupled dynamics and divide the positioning responsibilities between the scanner components. As a result, the multi-actuated scanner behavior is equivalent to that of a single X–Y–Z positioner with large range and high speed. The scanner of the designed AFM is composed of five nano-positioners, features 6μm out-of-plane and 120μm lateral ranges and is capable of high-speed operation. The presented AFM has a modular design with laser spot size of 3.5μm suitable for small cantilever, an optical view of the sample and probe, a conveniently large waterproof sample stage and a 20MHz data throughput for high resolution image acquisition at high imaging speeds. This AFM is used to visualize etching of calcite in a solution of sulfuric acid. Layer-by-layer dissolution and pit formation along the crystalline lines in a low pH environment is observed in real time.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
This paper presents the design and control of a high-speed and large-range atomic force microscopy (AFM). A multi-actuation scheme is proposed where several nano-positioners cooperate to achieve the range and speed requirements. A simple data-based control design methodology is presented to effectively operate the AFM scanner components. The proposed controllers compensate for the coupled dynamics and divide the positioning responsibilities between the scanner components. As a result, the multi-actuated scanner behavior is equivalent to that of a single X–Y–Z positioner with large range and high speed. The scanner of the designed AFM is composed of five nano-positioners, features 6μm out-of-plane and 120μm lateral ranges and is capable of high-speed operation. The presented AFM has a modular design with laser spot size of 3.5μm suitable for small cantilever, an optical view of the sample and probe, a conveniently large waterproof sample stage and a 20MHz data throughput for high resolution image acquisition at high imaging speeds. This AFM is used to visualize etching of calcite in a solution of sulfuric acid. Layer-by-layer dissolution and pit formation along the crystalline lines in a low pH environment is observed in real time.
2015
8.
Ahmed Owais; Mazen M Khaled; Bekir S Yilbas; Numan Abu-Dheir; Kripa K Varanasi; Kamal Y Toumi
Surface and wetting characteristics of textured bisphenol-A based polycarbonate surfaces: Acetone-induced crystallization texturing methods Journal Article
In: Journal of Applied Polymer Science, vol. 133, no. 14, 2015, ISSN: 43074.
@article{MRL_AFM_Surface_Wetting_Poly_Surfaces,
title = {Surface and wetting characteristics of textured bisphenol-A based polycarbonate surfaces: Acetone-induced crystallization texturing methods},
author = {Ahmed Owais and Mazen M Khaled and Bekir S Yilbas and Numan Abu-Dheir and Kripa K Varanasi and Kamal Y Toumi},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/app.43074},
doi = {https://doi.org/10.1002/app.43074},
issn = {43074},
year = {2015},
date = {2015-11-12},
journal = {Journal of Applied Polymer Science},
volume = {133},
number = {14},
publisher = {Wiley},
abstract = {ABSTRACT Polycarbonate (PC) sheet is a promising material for facile patterning to induce hydrophobic self-cleaning and dust repelling properties for photovoltaic panels’ protection. An investigation to texture PC sheet surfaces to develop a self-cleaning structure using solvent induced-crystallization is carried out using acetone. Acetone is applied in both liquid and vapor states to generate a hierarchically structured surface that would improve its contacts angle and therefore improve hydrophobicity. The surface texture is investigated and characterized using atomic force microscopy, contact angle technique (Goniometer), optical microscopy, ultraviolet-visible spectroscopy (UV–vis) and Fourier transform infrared spectroscopy. The findings revealed that the liquid acetone-induced crystallization of PC surface leads to a hierarchal and hydrophobic surface with an average contact angle of 135° and average transmittance <2%. However, the acetone vapor induced-crystallization results in a slightly hydrophilic hierarchal textured surface with high transmittance; in which case, average contact angle of 89° and average transmittance of 69% are achieved. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43074.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
ABSTRACT Polycarbonate (PC) sheet is a promising material for facile patterning to induce hydrophobic self-cleaning and dust repelling properties for photovoltaic panels’ protection. An investigation to texture PC sheet surfaces to develop a self-cleaning structure using solvent induced-crystallization is carried out using acetone. Acetone is applied in both liquid and vapor states to generate a hierarchically structured surface that would improve its contacts angle and therefore improve hydrophobicity. The surface texture is investigated and characterized using atomic force microscopy, contact angle technique (Goniometer), optical microscopy, ultraviolet-visible spectroscopy (UV–vis) and Fourier transform infrared spectroscopy. The findings revealed that the liquid acetone-induced crystallization of PC surface leads to a hierarchal and hydrophobic surface with an average contact angle of 135° and average transmittance <2%. However, the acetone vapor induced-crystallization results in a slightly hydrophilic hierarchal textured surface with high transmittance; in which case, average contact angle of 89° and average transmittance of 69% are achieved. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43074.
7.
Andreas Schuh; Iman Soltani Bozchalooi; Ivo W Rangelow; Kamal Youcef-Toumi
Multi-eigenmode control for high material contrast in bimodal and higher harmonic atomic force microscopy Journal Article
In: Nanotechnology, vol. 26, no. 23, pp. 235706, 2015.
@article{MRL_Multi_Eigenmode,
title = {Multi-eigenmode control for high material contrast in bimodal and higher harmonic atomic force microscopy},
author = {Andreas Schuh and Iman Soltani Bozchalooi and Ivo W Rangelow and Kamal Youcef-Toumi},
url = {https://doi.org/10.1088/0957-4484/26/23/235706},
doi = {10.1088/0957-4484/26/23/235706},
year = {2015},
date = {2015-05-01},
journal = {Nanotechnology},
volume = {26},
number = {23},
pages = {235706},
publisher = {IOP Publishing},
abstract = {High speed imaging and mapping of nanomechanical properties in atomic force microscopy (AFM) allows the observation and characterization of dynamic sample processes. Recent developments involve several cantilever frequencies in a multifrequency approach. One method actuates the first eigenmode for topography imaging and records the excited higher harmonics to map nanomechanical properties of the sample. To enhance the higher frequencies’ response two or more eigenmodes are actuated simultaneously, where the higher eigenmode(s) are used to quantify the nanomechanics. In this paper, we combine each imaging methodology with a novel control approach. It modifies the Q factor and resonance frequency of each eigenmode independently to enhance the force sensitivity and imaging bandwidth. It allows us to satisfy the different requirements for the first and higher eigenmode. The presented compensator is compatible with existing AFMs and can be simply attached with minimal modifications. Different samples are used to demonstrate the improvement in nanomechanical contrast mapping and imaging speed of tapping mode AFM in air. The experiments indicate most enhanced nanomechanical contrast with low Q factors of the first and high Q factors of the higher eigenmode. In this scenario, the cantilever topography imaging rate can also be easily improved by a factor of 10.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
High speed imaging and mapping of nanomechanical properties in atomic force microscopy (AFM) allows the observation and characterization of dynamic sample processes. Recent developments involve several cantilever frequencies in a multifrequency approach. One method actuates the first eigenmode for topography imaging and records the excited higher harmonics to map nanomechanical properties of the sample. To enhance the higher frequencies’ response two or more eigenmodes are actuated simultaneously, where the higher eigenmode(s) are used to quantify the nanomechanics. In this paper, we combine each imaging methodology with a novel control approach. It modifies the Q factor and resonance frequency of each eigenmode independently to enhance the force sensitivity and imaging bandwidth. It allows us to satisfy the different requirements for the first and higher eigenmode. The presented compensator is compatible with existing AFMs and can be simply attached with minimal modifications. Different samples are used to demonstrate the improvement in nanomechanical contrast mapping and imaging speed of tapping mode AFM in air. The experiments indicate most enhanced nanomechanical contrast with low Q factors of the first and high Q factors of the higher eigenmode. In this scenario, the cantilever topography imaging rate can also be easily improved by a factor of 10.
6.
Hadi Nia; Lin Han; Iman Soltani; Peter Roughley; Kamal Youcef-Toumi; Alan Grodzinsky; Christine Ortiz
Aggrecan Nanoscale Solid–Fluid Interactions Are a Primary Determinant of Cartilage Dynamic Mechanical Properties Journal Article
In: ACS nano, vol. 9, 2015, ISSN: 2614-2625.
@article{MRL_AFM_Agreecan_Nanoscale_Solid,
title = {Aggrecan Nanoscale Solid–Fluid Interactions Are a Primary Determinant of Cartilage Dynamic Mechanical Properties},
author = {Hadi Nia and Lin Han and Iman Soltani and Peter Roughley and Kamal Youcef-Toumi and Alan Grodzinsky and Christine Ortiz},
doi = {10.1021/nn5062707},
issn = {2614-2625},
year = {2015},
date = {2015-03-10},
journal = {ACS nano},
volume = {9},
publisher = {ACS},
abstract = {Poroelastic interactions between interstitial fluid and the extracellular
matrix of connective tissues are critical to biological and pathophysiological functions
involving solute transport, energy dissipation, self-stiffening and lubrication. However,
the molecular origins of poroelasticity at the nanoscale are largely unknown. Here, the
broad-spectrum dynamic nanomechanical behavior of cartilage aggrecan monolayer is
revealed for the first time, including the equilibrium and instantaneous moduli and the
peak in the phase angle of the complex modulus. By performing a length scale study
and comparing the experimental results to theoretical predictions, we confirm that the
mechanism underlying the observed dynamic nanomechanics is due to solidfluid
interactions (poroelasticity) at the molecular scale. Utilizing finite element modeling, the molecular-scale hydraulic permeability of the aggrecan assembly was quantified (kaggrecan = (4.8 ( 2.8) 1015 m4
/N 3 s) and found to be similar to the nanoscale hydraulic permeability of intact normal cartilage tissue
but much lower than that of early diseased tissue. The mechanisms underlying aggrecan poroelasticity were further investigated by altering electrostatic
interactions between the molecule's constituent glycosaminoglycan chains: electrostatic interactions dominated steric interactions in governing molecular
behavior. While the hydraulic permeability of aggrecan layers does not change across species and age, aggrecan from adult human cartilage is stiffer than
the aggrecan from newborn human tissue.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Poroelastic interactions between interstitial fluid and the extracellular
matrix of connective tissues are critical to biological and pathophysiological functions
involving solute transport, energy dissipation, self-stiffening and lubrication. However,
the molecular origins of poroelasticity at the nanoscale are largely unknown. Here, the
broad-spectrum dynamic nanomechanical behavior of cartilage aggrecan monolayer is
revealed for the first time, including the equilibrium and instantaneous moduli and the
peak in the phase angle of the complex modulus. By performing a length scale study
and comparing the experimental results to theoretical predictions, we confirm that the
mechanism underlying the observed dynamic nanomechanics is due to solidfluid
interactions (poroelasticity) at the molecular scale. Utilizing finite element modeling, the molecular-scale hydraulic permeability of the aggrecan assembly was quantified (kaggrecan = (4.8 ( 2.8) 1015 m4
/N 3 s) and found to be similar to the nanoscale hydraulic permeability of intact normal cartilage tissue
but much lower than that of early diseased tissue. The mechanisms underlying aggrecan poroelasticity were further investigated by altering electrostatic
interactions between the molecule's constituent glycosaminoglycan chains: electrostatic interactions dominated steric interactions in governing molecular
behavior. While the hydraulic permeability of aggrecan layers does not change across species and age, aggrecan from adult human cartilage is stiffer than
the aggrecan from newborn human tissue.
matrix of connective tissues are critical to biological and pathophysiological functions
involving solute transport, energy dissipation, self-stiffening and lubrication. However,
the molecular origins of poroelasticity at the nanoscale are largely unknown. Here, the
broad-spectrum dynamic nanomechanical behavior of cartilage aggrecan monolayer is
revealed for the first time, including the equilibrium and instantaneous moduli and the
peak in the phase angle of the complex modulus. By performing a length scale study
and comparing the experimental results to theoretical predictions, we confirm that the
mechanism underlying the observed dynamic nanomechanics is due to solidfluid
interactions (poroelasticity) at the molecular scale. Utilizing finite element modeling, the molecular-scale hydraulic permeability of the aggrecan assembly was quantified (kaggrecan = (4.8 ( 2.8) 1015 m4
/N 3 s) and found to be similar to the nanoscale hydraulic permeability of intact normal cartilage tissue
but much lower than that of early diseased tissue. The mechanisms underlying aggrecan poroelasticity were further investigated by altering electrostatic
interactions between the molecule's constituent glycosaminoglycan chains: electrostatic interactions dominated steric interactions in governing molecular
behavior. While the hydraulic permeability of aggrecan layers does not change across species and age, aggrecan from adult human cartilage is stiffer than
the aggrecan from newborn human tissue.
2014
5.
Soltani I Bozchalooi; Kamal Youcef-Toumi
Control design for division and compensation with application to high-speed/large-range nano-positioning Proceedings Article
In: 2014 American Control Conference, pp. 1643-1648, IEEE IEEE, 2014, ISBN: 978-1-4799-3274-0.
@inproceedings{MRL_AFM_Nano_Positioning_Control,
title = {Control design for division and compensation with application to high-speed/large-range nano-positioning},
author = {Soltani I Bozchalooi and Kamal Youcef-Toumi},
url = {https://ieeexplore.ieee.org/document/6859262},
doi = {10.1109/ACC.2014.6859262},
isbn = {978-1-4799-3274-0},
year = {2014},
date = {2014-07-21},
booktitle = {2014 American Control Conference},
pages = {1643-1648},
publisher = {IEEE},
organization = {IEEE},
abstract = {In this paper an easy to implement control design strategy is proposed to achieve large range and high speed nano-positioning. The designed controllers aim to divide the positioning task between multiple large range/low speed and small range/high speed nano-positioners. Each controller assigns the proper frequency range to individual nano-positioners, and simultaneously compensates for the corresponding excited dynamics at high positioning speeds. Control design is formulated in the form of several single input-single output (SISO) system identification problems. The proposed approach removes the need for fundamental changes in the design of the conventional scanners such as piezo tubes for applications necessitating high speed and large range nano-positioning.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
In this paper an easy to implement control design strategy is proposed to achieve large range and high speed nano-positioning. The designed controllers aim to divide the positioning task between multiple large range/low speed and small range/high speed nano-positioners. Each controller assigns the proper frequency range to individual nano-positioners, and simultaneously compensates for the corresponding excited dynamics at high positioning speeds. Control design is formulated in the form of several single input-single output (SISO) system identification problems. The proposed approach removes the need for fundamental changes in the design of the conventional scanners such as piezo tubes for applications necessitating high speed and large range nano-positioning.
4.
Iman Soltani Bozchalooi; Kamal Youcef-Toumi
Multi-actuation and PI control: A simple recipe for high-speed and large-range atomic force microscopy Journal Article
In: Ültramicroscopy, vol. 146, pp. 117 - 124, 2014, ISSN: 0304-3991.
@article{MRL_AFM_Multi_PI_control,
title = {Multi-actuation and PI control: A simple recipe for high-speed and large-range atomic force microscopy},
author = {Iman Soltani Bozchalooi and Kamal Youcef-Toumi},
url = {http://www.sciencedirect.com/science/article/pii/S0304399114001491},
doi = {https://doi.org/10.1016/j.ultramic.2014.07.010},
issn = {0304-3991},
year = {2014},
date = {2014-01-01},
journal = {Ültramicroscopy},
volume = {146},
pages = {117 - 124},
abstract = {High speed atomic force microscopy enables observation of dynamic nano-scale processes. However, maintaining a minimal interaction force between the sample and the probe is challenging at high speed specially when using conventional piezo-tubes. While rigid AFM scanners are operational at high speeds with the drawback of reduced tracking range, multi-actuation schemes have shown potential for high-speed and large-range imaging. Here we present a method to seamlessly incorporate additional actuators into conventional AFMs. The equivalent behavior of the resulting multi-actuated setup resembles that of a single high-speed and large-range actuator with maximally flat frequency response. To achieve this, the dynamics of the individual actuators and their couplings are treated through a simple control scheme. Upon the implementation of the proposed technique, commonly used PI controllers are able to meet the requirements of high-speed imaging. This forms an ideal platform for retroactive enhancement of existing AFMs with minimal cost and without compromise on the tracking range. A conventional AFM with tube scanner is retroactively enhanced through the proposed method and shows an order of magnitude improvement in closed loop bandwidth performance while maintaining large range. The effectiveness of the method is demonstrated on various types of samples imaged in contact and tapping modes, in air and in liquid.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
High speed atomic force microscopy enables observation of dynamic nano-scale processes. However, maintaining a minimal interaction force between the sample and the probe is challenging at high speed specially when using conventional piezo-tubes. While rigid AFM scanners are operational at high speeds with the drawback of reduced tracking range, multi-actuation schemes have shown potential for high-speed and large-range imaging. Here we present a method to seamlessly incorporate additional actuators into conventional AFMs. The equivalent behavior of the resulting multi-actuated setup resembles that of a single high-speed and large-range actuator with maximally flat frequency response. To achieve this, the dynamics of the individual actuators and their couplings are treated through a simple control scheme. Upon the implementation of the proposed technique, commonly used PI controllers are able to meet the requirements of high-speed imaging. This forms an ideal platform for retroactive enhancement of existing AFMs with minimal cost and without compromise on the tracking range. A conventional AFM with tube scanner is retroactively enhanced through the proposed method and shows an order of magnitude improvement in closed loop bandwidth performance while maintaining large range. The effectiveness of the method is demonstrated on various types of samples imaged in contact and tapping modes, in air and in liquid.
2013
3.
Hadi Nia; Iman Soltani; Yang Li; Lin Han; Han-Hwa Hung; Eliot Frank; Kamal Youcef-Toumi; Christine Ortiz; Alan Grodzinsky
High-Bandwidth AFM-Based Rheology Reveals that Cartilage is Most Sensitive to High Loading Rates at Early Stages of Impairment Journal Article
In: Biophysical journal, vol. 104, pp. 1529-37, 2013, ISSN: 00063496.
@article{MRL_AFM_Cartilage_Early_Impairment,
title = {High-Bandwidth AFM-Based Rheology Reveals that Cartilage is Most Sensitive to High Loading Rates at Early Stages of Impairment},
author = {Hadi Nia and Iman Soltani and Yang Li and Lin Han and Han-Hwa Hung and Eliot Frank and Kamal Youcef-Toumi and Christine Ortiz and Alan Grodzinsky},
url = {https://dspace.mit.edu/handle/1721.1/92000},
doi = {10.1016/j.bpj.2013.02.048},
issn = {00063496},
year = {2013},
date = {2013-04-02},
journal = {Biophysical journal},
volume = {104},
pages = {1529-37},
publisher = {Elsevier B.V},
abstract = {Utilizing a newly developed atomic-force-microscopy-based wide-frequency rheology system, we measured the dynamic nanomechanical behavior of normal and glycosaminoglycan (GAG)-depleted cartilage, the latter representing matrix degradation that occurs at the earliest stages of osteoarthritis. We observed unique variations in the frequency-dependent stiffness and hydraulic permeability of cartilage in the 1 Hz-to-10 kHz range, a frequency range that is relevant to joint motions from normal ambulation to high-frequency impact loading. Measurement in this frequency range is well beyond the capabilities of typical commercial atomic force microscopes. We showed that the dynamic modulus of cartilage undergoes a dramatic alteration after GAG loss, even with the collagen network still intact: whereas the magnitude of the dynamic modulus decreased two- to threefold at higher frequencies, the peak frequency of the phase angle of the modulus (representing fluid-solid frictional dissipation) increased 15-fold from 55 Hz in normal cartilage to 800 Hz after GAG depletion. These results, based on a fibril-reinforced poroelastic finite-element model, demonstrated that GAG loss caused a dramatic increase in cartilage hydraulic permeability (up to 25-fold), suggesting that early osteoarthritic cartilage is more vulnerable to higher loading rates than to the conventionally studied “loading magnitude”. Thus, over the wide frequency range of joint motion during daily activities, hydraulic permeability appears the most sensitive marker of early tissue degradation.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Utilizing a newly developed atomic-force-microscopy-based wide-frequency rheology system, we measured the dynamic nanomechanical behavior of normal and glycosaminoglycan (GAG)-depleted cartilage, the latter representing matrix degradation that occurs at the earliest stages of osteoarthritis. We observed unique variations in the frequency-dependent stiffness and hydraulic permeability of cartilage in the 1 Hz-to-10 kHz range, a frequency range that is relevant to joint motions from normal ambulation to high-frequency impact loading. Measurement in this frequency range is well beyond the capabilities of typical commercial atomic force microscopes. We showed that the dynamic modulus of cartilage undergoes a dramatic alteration after GAG loss, even with the collagen network still intact: whereas the magnitude of the dynamic modulus decreased two- to threefold at higher frequencies, the peak frequency of the phase angle of the modulus (representing fluid-solid frictional dissipation) increased 15-fold from 55 Hz in normal cartilage to 800 Hz after GAG depletion. These results, based on a fibril-reinforced poroelastic finite-element model, demonstrated that GAG loss caused a dramatic increase in cartilage hydraulic permeability (up to 25-fold), suggesting that early osteoarthritic cartilage is more vulnerable to higher loading rates than to the conventionally studied “loading magnitude”. Thus, over the wide frequency range of joint motion during daily activities, hydraulic permeability appears the most sensitive marker of early tissue degradation.
2012
2.
Soltani I Bozchalooi; Kamal Youcef-Toumi; D J Burns; Georg E Fantner
A vibration suppression approach to high-speed atomic force microscopy Proceedings Article
In: 2012 American Control Conference (ACC), pp. 3797-3802, ACC ACC, 2012, ISBN: 978-1-4577-1096-4.
@inproceedings{MRL_AFM_Vibration_Suppression,
title = {A vibration suppression approach to high-speed atomic force microscopy},
author = {Soltani I Bozchalooi and Kamal Youcef-Toumi and D J Burns and Georg E Fantner},
url = {https://ieeexplore.ieee.org/document/6315281},
doi = {10.1109/ACC.2012.6315281},
isbn = {978-1-4577-1096-4},
year = {2012},
date = {2012-10-02},
booktitle = {2012 American Control Conference (ACC)},
pages = {3797-3802},
publisher = {ACC},
organization = {ACC},
abstract = {The possibility of many new applications and novel scientific observations can be provided by efficient and reliable high-speed atomic force microscopy techniques. However, the reliability of the AFM images decreases significantly as the imaging speed is increased to levels required for the targeted real-time observation of nano-scale phenomenon. One of the main reasons behind this limitation is the excitation of the AFM dynamics at high scan speeds. In this research we propose a piezo based, feedforward controlled, counter actuation mechanism to compensate for the excited out-of-plane scanner dynamics. For this purpose the AFM controller output is properly filtered via a linear compensator and then applied to a counter actuating piezo. 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.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
The possibility of many new applications and novel scientific observations can be provided by efficient and reliable high-speed atomic force microscopy techniques. However, the reliability of the AFM images decreases significantly as the imaging speed is increased to levels required for the targeted real-time observation of nano-scale phenomenon. One of the main reasons behind this limitation is the excitation of the AFM dynamics at high scan speeds. In this research we propose a piezo based, feedforward controlled, counter actuation mechanism to compensate for the excited out-of-plane scanner dynamics. For this purpose the AFM controller output is properly filtered via a linear compensator and then applied to a counter actuating piezo. 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.
2011
1.
Tavakoli H Nia; L Han; Y Li; Soltani I Bozchalooi; H Hung; E Frank; K Youcef-Toumi; A Grodzinsky; C Orti
The effect of GAG depletion on cartilage nanoscale hydraulic permeability Proceedings Article
In: ORS 2012 Annual Meeting, pp. 0282, ORS ORS, 2011, ISBN: 978-1-4577-1096-4.
@inproceedings{MRL_AFM_GAG_Depletion,
title = {The effect of GAG depletion on cartilage nanoscale hydraulic permeability},
author = {Tavakoli H Nia and L Han and Y Li and Soltani I Bozchalooi and H Hung and E Frank and K Youcef-Toumi and A Grodzinsky and C Orti},
url = {http://www.ors.org/Transactions/58/0282.pdf},
doi = {10.1109/ACC.2012.6315281},
isbn = {978-1-4577-1096-4},
year = {2011},
date = {2011-01-01},
booktitle = {ORS 2012 Annual Meeting},
pages = {0282},
publisher = {ORS},
organization = {ORS},
abstract = {The advent of new time-dependent nanomechanical methods has recently enabled the quantification of cartilage tissue poroelasticity and hydraulic permeability, k, at the nanoscale [1-3] and holds great potential for early detection of pathological changes and diagnosis of osteoarthritis (OA). It is known that at the macroscale, tissue hydraulic permeability can undergo several order-of-magnitude changes due to OA [4] while the equilibrium stiffness may vary by only a factor of 2 [5]. This is because GAG chains are the main determinant of the pore size (consequently, hydraulic permeability) of cartilage while they contribute only partially to the compression stiffness of the tissue. Here, we extend the technique of atomic force microscope-based dynamic oscillatory nanoindentation to a larger frequency range (1-10,000 Hz) and compare these data to finite element analysis simulations to study the effect of GAG content, relevant to early stage OA.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
The advent of new time-dependent nanomechanical methods has recently enabled the quantification of cartilage tissue poroelasticity and hydraulic permeability, k, at the nanoscale [1-3] and holds great potential for early detection of pathological changes and diagnosis of osteoarthritis (OA). It is known that at the macroscale, tissue hydraulic permeability can undergo several order-of-magnitude changes due to OA [4] while the equilibrium stiffness may vary by only a factor of 2 [5]. This is because GAG chains are the main determinant of the pore size (consequently, hydraulic permeability) of cartilage while they contribute only partially to the compression stiffness of the tissue. Here, we extend the technique of atomic force microscope-based dynamic oscillatory nanoindentation to a larger frequency range (1-10,000 Hz) and compare these data to finite element analysis simulations to study the effect of GAG content, relevant to early stage OA.