Michael G. Ruppert

Michael G. Ruppert
University of Technology Sydney | UTS · School of Mechanical and Mechatronic Engineering

Dr. Dipl.-Ing.

About

55
Publications
13,451
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
674
Citations
Introduction
Michael Ruppert is currently a lecturer in Mechatronics at the University of Technology Sydney. He has expertise in high performance mechatronics systems, automation technology, applied automatic control, applied systems theory, signal processing and electrical engineering. His research interests include the control, estimation and sensing instrumentation of microelectromechanical (MEMS) systems for nanometrology and high-precision positioning applications.
Additional affiliations
January 2017 - present
University of Newcastle Australia
Position
  • Research Associate
Description
  • http://www.precisionmechatronicslab.com/
March 2013 - December 2016
University of Newcastle Australia
Position
  • PhD Student
Description
  • http://mechatronics.newcastle.edu.au
Education
September 2006 - March 2013
University of Stuttgart
Field of study
  • Mechatronics (Automatisierungstechnik in der Production)

Publications

Publications (55)
Article
High resolution atomic force microscopy is routinely performed at ultra-high vacuum and at low temperatures by employing a qPlus tuning fork sensor. Due to its intrinsic self-sensing capability, very high...
Article
Microcantilever probes for tip‐enhanced Raman spectroscopy (TERS) have a grainy metal coating that may exhibit multiple plasmon hotspots near the tip apex, which may compromise spatial resolution and introduce imaging artefacts. It is also possible that the optical hotspot may not occur at the mechanical apex, which introduces an offset between TER...
Article
Nanoceria has evolved as one of the promising nanomaterials due to its unique enzyme-like properties, including excellent oxidase mimetic activity, which significantly increases in the presence of fluoride ions. However,...
Article
Full-text available
Effective demodulation of amplitude and phase is a requirement in a wide array of applications. Recent efforts have increased the demodulation performance, in particular, the Lyapunov demodulator allows bandwidths up to the carrier frequency of the signal. However, being inherently restricted to first-order filtering of the input signal, it is high...
Article
This Article describes a method for the characterization of the imaging performance of tip-enhanced Raman spectroscopy probes. The proposed method identifies single-walled carbon nanotubes that are suitable as one-dimensional Raman scattering objects by using atomic force microscope maps and exciting the radial breathing mode using 785 nm illuminat...
Article
Cerium oxide nanoparticles (CeNPs) exhibit excellent in vitro and in vivo antioxidant properties, determined by the redox switching of surface cerium ions between their two oxidation states (Ce3+ and Ce4+). It is known that ligands such as triethyl phosphite (TEP) can tune the redox behavior of CeNPs and change their biological enzyme-mimetic activ...
Article
Non-contact atomic force microscopy (AFM) with CO-functionalized tips allows visualization of the chemical structure of adsorbed molecules and identify individual inter- and intramolecular bonds. This technique enables in-depth studies of on-surface reactions and self-assembly processes. Herein, we analyze the suitability of qPlus sensors, which ar...
Article
The use of integrated on-chip actuation simplifies the identification of a cantilever resonance, can improve imaging speed, and enables the use of smaller cantilevers, which is required for low-force imaging at high speed. This article describes a cantilever with on-chip actuation and novel dual-sensing capabilities for AFM. The dual-sensing config...
Article
Full-text available
QPlus sensors are non-contact atomic force microscope probes constructed from a quartz tuning fork and a tungsten wire with an electrochemically etched tip. These probes are self-sensing and offer an atomic-scale spatial resolution. Therefore, qPlus sensors are routinely used to visualize the chemical structure of adsorbed organic molecules via the...
Article
Piezoelectric benders are widely used in industrial applications due to their low-cost and compact size. However, due to the large relative size and cost of displacement sensors, bender actuators are often operated in open-loop or with feed-forward control, which can limit positioning accuracy to 20% of full-scale. To improve the positioning accura...
Chapter
Active atomic force microscope cantilevers with on-chip actuation and sensing provide several advantages over passive cantilevers which rely on piezoacoustic base-excitation and the optical beam deflection measurement. Most importantly, these cantilevers provide clean frequency responses, the possibility of down-scaling and parallelization to canti...
Article
Active atomic force microscope cantilevers with on-chip actuation and sensing provide several advantages over passive cantilevers which rely on piezoacoustic base-excitation and optical beam deflection measurement. Active microcantilevers exhibit a clean frequency response, provide a path-way to miniturization and parallelization and avoid the need...
Article
This article derives design guidelines for integrating strain gauges into the electrodes of piezoelectric bending actuators. The proposed sensor can estimate the actuator tip displacement in response to an applied voltage and an external applied tip force. The actuator load force is also estimated with an accuracy of 8% full scale by approximating...
Article
In this article, boundary element method simulations are used to optimise the geometry of silver and gold nanocone probes to maximise the localised electric field enhancement and tune the near‐field resonance wavelength. These objectives are expected to maximise the sensitivity of tip‐enhanced Raman microscopes. Similar studies have used limited pa...
Conference Paper
Full-text available
Integrated on-chip actuation and sensing in micro-cantilevers for atomic force microscopy (AFM) allows faster scanning speeds, cleaner frequency responses and smaller cantilevers. However, a single integrated sensor suffers from cross-coupling between displacements originating from tip-sample forces and direct actuation. This paper addresses this i...
Article
Full-text available
The lock-in amplifier is a crucial component in many applications requiring high-resolution displacement sensing; it's purpose is to estimate the amplitude and phase of a periodic signal, potentially corrupted by noise, at a frequency determined by a reference signal. Where the noise can be approximated by a stationary Gaussian process, such as the...
Article
Full-text available
In the fast growing field of multifrequency atomic force microscopy (AFM), the benefits of using higher-order modes has been extensively reported on. However, higher modes of AFM cantilevers are difficult to instrument and Q control is challenging owing to their high frequency nature. At these high frequencies, the latencies in the computations and...
Article
Full-text available
This article compares the performance of traditional and recently proposed demodulators for multifrequency atomic force microscopy. The compared methods include the lock-in amplifier, coherent demodulator, Kalman filter, Lyapunov filter, and direct-design demodulator. Each method is implemented on a field-programmable gate array (FPGA) with a sampl...
Article
Constant-force contact-mode atomic force microscopy (AFM) relies on a feedback control system to regulate the tip-sample interaction during imaging. Due to limitations in actuators and control, the bandwidth of the regulation system is typically small. Therefore, the scan rate is usually limited in order to guarantee a desirable image quality for a...
Preprint
Full-text available
Effective demodulation of amplitude and phase is a requirement in a wide array of applications. Recent efforts have increased the demodulation performance, in particular, the Lyapunov demodulator allows bandwidths up to the carrier frequency of the signal. However, being inherently restricted to a single order filtering of the input signal, signal...
Conference Paper
Full-text available
Effective demodulation of amplitude and phase is a requirement in a wide array of applications. Recent efforts have increased the demodulation performance, in particular, the Lyapunov demodulator allows bandwidths up to the carrier frequency of the signal. However, being inherently restricted to a single order filtering of the input signal, signal...
Article
Full-text available
To facilitate further miniaturization of atomic force microscopy (AFM) cantilevers and to eliminate the standard optical beam deflection sensor, integrated piezoelectric actuation and sensing on the chip level is a promising option. This article presents a topology optimization method for dynamic mode AFM cantilevers that maximizes the sensitivity...
Article
Full-text available
System-based demodulators in the form of a Kalman and Lyapunov filter have been demonstrated to significantly outperform traditional demodulators, such as the lock-in amplifier, in bandwidth sensitive applications, for example high-speed atomic force microscopy. Building on their closed loop architecture, this article describes a broader class of h...
Article
The following paper was selected for the 2018 IEEE Transactions on Control Systems Technology Outstanding Paper Award from papers that appeared in 2016–2017: “Multimode Q Control in Tapping-Mode AFM: Enabling Imaging on Higher Flexural Eigenmodes” by Michael G. Ruppert and S. O. Reza Moheimani Vol. 24, No. 4, pp. 1149–1159, July 2016.
Article
A major challenge in atomic force microscopy is to reduce the scan duration while retaining the image quality. Conventionally, the scan rate is restricted to a sufficiently small value in order to ensure a desirable image quality as well as a safe tip-sample contact force. This usually results in a conservative scan rate for samples that have a lar...
Preprint
Full-text available
A major challenge in Atomic Force Microscopy (AFM) is to reduce the scan duration while retaining the image quality. Conventionally, the scan rate is restricted to a sufficiently small value in order to ensure a desirable image quality as well as a safe tip-sample contact force. This usually results in a conservative scan rate for samples that have...
Article
Full-text available
Atomic force microscope (AFM) cantilevers with integrated actuation and sensing provide several distinct advantages over conventional cantilever instrumentation. These include clean frequency responses, the possibility of down-scaling and parallelization to cantilever arrays as well as the absence of optical interference. While cantilever microfabr...
Conference Paper
Full-text available
This article presents a novel cantilever design approach to place higher mode frequencies within a specific frequency band to alleviate instrumentation and Q control feasibility. This work is motivated by the emerging field of multifrequency atomic force microscopy (AFM) which involves the excitation and/or detection of several cantilever modes at...
Article
Full-text available
An important issue in the emerging field of multifrequency atomic force microscopy (MF-AFM) is the accurate and fast demodulation of the cantilever-tip deflection signal. As this signal consists of multiple frequency components and noise processes, a lock-in amplifier is typically employed for its narrowband response. However, this demodulator suff...
Article
Full-text available
The quality (Q) factor is an important parameter of the resonance of the microcantilever as it determines both imaging bandwidth and force sensitivity. The ability to control the Q factor of multiple modes is believed to be of great benefit for atomic force microscopy techniques involving multiple eigenmodes. In this paper, we propose a novel canti...
Article
Full-text available
In this review paper, traditional and novel demodulation methods applicable to amplitude-modulation atomic force microscopy are implemented on a widely used digital processing system. As a crucial bandwidth-limiting component in the z-axis feedback loop of an atomic force microscope, the purpose of the demodulator is to obtain estimates of amplitud...
Article
Full-text available
We demonstrate a novel tracking controller formulation based on a linear time-varying Kalman filter to regulate amplitude and phase of a reference signal independently. The method is applicable to sinusoidal references such as spiral, cycloid and Lissajous trajectories which are commonly used for imaging in high-speed Atomic Force Microscopy (AFM)....
Article
In dynamic mode atomic force microscopy (AFM), the imaging bandwidth is governed by the slowest component in the open-loop chain consisting of the vertical actuator, cantilever and demodulator. While the common demodulation method is to use a lock-in amplifier (LIA), its performance is ultimately bounded by the bandwidth of the post-mixing low-pass...
Article
Full-text available
Self-sensing techniques for atomic force microscope (AFM) cantilevers have several advantageous characteristics compared to the optical beam deflection method. The possibility of down scaling, parallelization of cantilever arrays and the absence of optical interference associated imaging artifacts have led to an increased research interest in these...
Article
Full-text available
The atomic force microscope (AFM) is an invaluable scientific tool; however, its conventional implementation as a relatively costly macroscale system is a barrier to its more widespread use. A microelectromechanical systems (MEMS) approach to AFM design has the potential to significantly reduce the cost and complexity of the AFM, expanding its util...
Article
Full-text available
Emerging multifrequency atomic force microscopy (MF-AFM) methods rely on coherent demodulation of the cantilever deflection signal at multiple frequencies. These measurements are needed in order to close the z-axis feedback loop and to acquire complementary information on the tip-sample interaction. While the common method is to use a lock-in ampli...
Article
Full-text available
Using standard microelectromechanical system (MEMS) processes to coat a microcantilever with a piezoelectric layer results in a versatile transducer with inherent self-sensing capabilities. For applications in multifrequency atomic force microscopy (MF-AFM), we illustrate that a single piezoelectric layer can be simultaneously used for multimode ex...
Conference Paper
Full-text available
Various Atomic Force Microscopy (AFM) modes have emerged which rely on the excitation and detection of multiple eigenmodes of the microcantilever. The conventional control loops employed in multifrequency AFM (MF-AFM) such as bimodal imaging where the fundamental mode is used to map the topography and a higher eigenmode is used to map sample materi...
Article
Full-text available
A fundamental challenge in dynamic mode atomic force microscopy (AFM) is the estimation of the cantilever oscillation amplitude from the deflection signal, which might be distorted by noise and/or high-frequency components. When the cantilever is excited at resonance, its deflection is typically obtained via narrow-band demodulation using a lock-in...
Article
We present new insights into the modeling of the microcantilever in dynamic mode atomic force microscopy and outline a novel high-bandwidth tip-sample force estimation technique for the development of high-bandwidth z-axis control. Fundamental to the proposed technique is the assumption that in tapping mode atomic force microscopy, the tip-sample f...
Conference Paper
Full-text available
We evaluate two novel reciprocal self-sensing methods for tapping-mode atomic force microscopy (TM-AFM) utilizing charge measurement and charge actuation, respectively. A microcantilever, which can be batch fabricated through a standard microelectromechanical system (MEMS) process, is coated with a single piezoelectric layer and simultaneously used...
Article
Full-text available
This work proposes a novel self-sensing tapping-mode atomic force microscopy operation utilizing charge measurement. A microcantilever coated with a single piezoelectric layer is simultaneously used for actuation and deflection sensing. The cantilever can be batch fabricated with existing micro electro mechanical system processes. The setup enables...
Conference Paper
When operating the Atomic Force Microscope in tapping mode it is possible to decrease the quality factor of the microcantilever to enhance scan speed. A new field of Atomic Force Microscopy is evolving, which makes use of multiple frequency excitation and detection of the cantilever modes making it necessary to be able to control these modes and th...

Network

Cited By