ORCID Profile
0000-0003-2286-4929
Current Organisation
University of Technology Sydney
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In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Microelectromechanical Systems (MEMS) | Mechanical Engineering | Control Systems, Robotics and Automation | Mechanical engineering | Manufacturing Engineering | Microtechnology | Nanometrology | Microelectromechanical systems (MEMS) | Dynamics vibration and vibration control
Expanding Knowledge in Engineering | Machined Metal Products | Industrial Instruments | Industrial Machinery and Equipment | Medical Instruments | Scientific Instruments |
Publisher: Elsevier BV
Date: 11-2019
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 05-2020
Publisher: IEEE
Date: 07-2018
Publisher: IEEE
Date: 07-2016
Publisher: AIP Publishing
Date: 08-2017
DOI: 10.1063/1.4990451
Abstract: 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 cantilever design employing multiple piezoelectric transducers which are used for separated actuation and sensing, leading to guaranteed collocation of the first eight eigenmodes up to 3 MHz. The design minimizes the feedthrough usually observed with these systems by incorporating a guard trace on the cantilever chip. As a result, a multimode Q controller is demonstrated to be able to modify the quality factor of the first two eigenmodes over up to four orders of magnitude without sacrificing robust stability.
Publisher: IEEE
Date: 07-2017
Publisher: IEEE
Date: 07-2017
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 02-2020
Publisher: IEEE
Date: 07-2016
Publisher: Elsevier BV
Date: 04-2021
Publisher: IEEE
Date: 07-2013
Publisher: IOP Publishing
Date: 10-02-2022
Abstract: 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 so-called bond imaging technique. This is achieved by functionalizing the AFM tip with a single CO molecule and exciting the sensor at the first vertical cantilever resonance mode. Recent work using higher-order resonance modes has also resolved the chemical structure of single organic molecules. However, in these experiments, the image contrast can differ significantly from the conventional bond imaging contrast, which was suspected to be caused by unknown vibrations of the tip. This work investigates the source of these artefacts by using a combination of mechanical simulation and laser vibrometry to characterize a range of sensors with different tip wire geometries. The results show that increased tip mass and length cause increased torsional rotation of the tuning fork beam due to the off-center mounting of the tip wire, and increased flexural vibration of the tip. These undesirable motions cause lateral deflection of the probe tip as it approaches the s le, which is rationalized to be the cause of the different image contrast. The results also provide a guide for future probe development to reduce these issues.
Publisher: IEEE
Date: 06-2018
Publisher: American Chemical Society (ACS)
Date: 21-06-2022
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2016
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 12-2016
Publisher: IEEE
Date: 07-2019
Publisher: Elsevier BV
Date: 09-2020
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 07-2016
Publisher: Beilstein Institut
Date: 10-07-2017
DOI: 10.3762/BJNANO.8.142
Abstract: In this review paper, traditional and novel demodulation methods applicable to litude-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 litude and phase of the cantilever deflection signal in the presence of sensor noise or additional distinct frequency components. Specifically for modern multifrequency techniques, where higher harmonic and/or higher eigenmode contributions are present in the oscillation signal, the fidelity of the estimates obtained from some demodulation techniques is not guaranteed. To enable a rigorous comparison, the performance metrics tracking bandwidth, implementation complexity and sensitivity to other frequency components are experimentally evaluated for each method. Finally, the significance of an adequate demodulator bandwidth is highlighted during high-speed tapping-mode atomic force microscopy experiments in constant-height mode.
Publisher: Wiley
Date: 14-09-2020
DOI: 10.1002/JRS.5987
Publisher: Elsevier BV
Date: 03-2022
Publisher: Elsevier BV
Date: 2014
Publisher: IEEE
Date: 07-2019
Publisher: IEEE
Date: 05-2017
Publisher: Elsevier BV
Date: 05-2022
Publisher: Springer International Publishing
Date: 2021
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 03-2019
Publisher: Springer International Publishing
Date: 2021
Publisher: AIP Publishing
Date: 12-2013
DOI: 10.1063/1.4841855
Abstract: 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 the omission of the optical beam deflection technique which is commonly used to measure the cantilever oscillation litude. Due to the high amount of capacitive feedthrough in the measured charge signal, a feedforward control technique is employed to increase the dynamic range from less than 1 dB to approximately 35 dB. Experiments show that the conditioned charge signal achieves excellent signal-to-noise ratio and can therefore be used as a feedback signal for atomic force microscopy imaging.
Publisher: Elsevier BV
Date: 07-2017
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2TB01135B
Abstract: Nanoceria prepared with different Ce 3+ /Ce 4+ ratios show different oxidase mimetic activities. The activity is enhanced selectively in presence of fluoride ions and used for glutathione detection.
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2NR01062C
Abstract: Non-contact atomic force microscopy (AFM) with CO-functionalized tips allows visualizing the chemical structure of in idual adsorbed molecules. Particularly high image contrast is observed by exciting a torsional eigenmode of the AFM sensor.
Publisher: Beilstein Institut
Date: 07-01-2020
DOI: 10.3762/BJNANO.11.8
Abstract: This article compares the performance of traditional and recently proposed demodulators for multifrequency atomic force microscopy. The compared methods include the lock-in lifier, coherent demodulator, Kalman filter, Lyapunov filter, and direct-design demodulator. Each method is implemented on a field-programmable gate array (FPGA) with a s ling rate of 1.5 MHz. The metrics for comparison include the sensitivity to other frequency components and the magnitude of demodulation artifacts for a range of demodulator bandwidths. Performance differences are demonstrated through higher harmonic atomic force microscopy imaging.
Publisher: Elsevier BV
Date: 03-2021
Publisher: Elsevier BV
Date: 2019
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2022
Publisher: American Society of Mechanical Engineers
Date: 02-08-2015
Abstract: 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 s le material properties only focus on maintaining low bandwidth signals such as litude and/or frequency shift. However, the ability to perform additional high bandwidth control of the quality (Q) factor of the participating modes is believed to be imperative to unfolding the full potential of these methods. This can be achieved by employing a multi-mode Q control approach utilizing positive position feedback. The controller exhibits remarkable performance in arbitrarily modifying the Q factor of multiple eigenmodes as well as guaranteed stability properties when used on flexible structures with collocated actuators and sensors. A controller design method based on pole placement optimization is proposed for setting an arbitrary on-resonance Q factor of the participating eigenmodes. Experimental results using bimodal AFM imaging on a two component polymer s le are presented.
Publisher: Springer London
Date: 16-11-2019
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2BM00396A
Abstract: Cerium oxide nanoparticles (CeNPs) exhibit excellent
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 06-2020
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 03-2018
Publisher: IOP Publishing
Date: 02-01-2019
Abstract: 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 microfabrication technology has continuously advanced over the years, the overall design has remained largely unchanged a passive rectangular shaped cantilever design has been adopted as the industry wide standard. In this article, we demonstrate multimode AFM imaging on higher eigenmodes as well as bimodal AFM imaging with cantilevers using fully integrated piezoelectric actuation and sensing. The cantilever design maximizes the higher eigenmode deflection sensitivity by optimizing the transducer layout according to the strain mode shape. Without the need for feedthrough cancellation, the read-out method achieves close to zero actuator/sensor feedthrough and the sensitivity is sufficient to resolve the cantilever Brownian motion.
Publisher: Beilstein Institut
Date: 08-02-2018
DOI: 10.3762/BJNANO.9.47
Abstract: 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 lifier is typically employed for its narrowband response. However, this demodulator suffers inherent bandwidth limitations as high-frequency mixing products must be filtered out and several must be operated in parallel. Many MF-AFM methods require litude and phase demodulation at multiple frequencies of interest, enabling both z -axis feedback and phase contrast imaging to be achieved. This article proposes a model-based multifrequency Lyapunov filter implemented on a field-programmable gate array (FPGA) for high-speed MF-AFM demodulation. System descriptions and simulations are verified by experimental results demonstrating high tracking bandwidths, strong off-mode rejection and minor sensitivity to cross-coupling effects. Additionally, a five-frequency system operating at 3.5 MHz is implemented for higher harmonic litude and phase imaging up to 1 MHz.
Publisher: IEEE
Date: 07-2018
Publisher: IEEE
Date: 05-2017
Publisher: Beilstein Institut
Date: 24-02-2016
DOI: 10.3762/BJNANO.7.26
Abstract: 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 excitation and detection of the cantilever deflection. This is achieved by a charge sensor with a bandwidth of 10 MHz and dual feedthrough cancellation to recover the resonant modes that are heavily buried in feedthrough originating from the piezoelectric capacitance. The setup enables the omission of the commonly used piezoelectric stack actuator and optical beam deflection sensor, alleviating limitations due to distorted frequency responses and instrumentation cost, respectively. The proposed method benefits from a more than two orders of magnitude increase in deflection to strain sensitivity on the fifth eigenmode leading to a remarkable signal-to-noise ratio. Experimental results using bimodal AFM imaging on a two component polymer s le validate that the self-sensing scheme can therefore be used to provide both the feedback signal, for topography imaging on the fundamental mode, and phase imaging on the higher eigenmode.
Publisher: Beilstein Institut
Date: 06-02-2017
DOI: 10.3762/BJNANO.8.38
Abstract: 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 methods. However, for multifrequency AFM, the optimization of the transducer layout on the cantilever for higher order modes has not been addressed. To fully utilize an integrated piezoelectric transducer, this work alters the layout of the piezoelectric layer to maximize both the deflection of the cantilever and measured piezoelectric charge response for a given mode with respect to the spatial distribution of the strain. On a prototype cantilever design, significant increases in actuator and sensor sensitivities were achieved for the first four modes without any substantial increase in sensor noise. The transduction mechanism is specifically targeted at multifrequency AFM and has the potential to provide higher resolution imaging on higher order modes.
Publisher: IEEE
Date: 13-07-2020
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 11-2014
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 02-2017
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 08-2019
Start Date: 08-2024
End Date: 07-2027
Amount: $444,471.00
Funder: Australian Research Council
View Funded ActivityStart Date: 06-2022
End Date: 06-2024
Amount: $210,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 04-2019
End Date: 04-2020
Amount: $438,783.00
Funder: Australian Research Council
View Funded ActivityStart Date: 10-2021
End Date: 10-2023
Amount: $183,437.00
Funder: Australian Research Council
View Funded Activity