2021 |
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6. | M. G. Ruppert; A. J. Fleming; Y. K. Yong Active atomic force microscope cantilevers with integrated device layer piezoresistive sensors Journal Article In: Sensors & Actuators: A. Physical, vol. 319, pp. 112519, 2021, ISSN: 0924-4247. Abstract | Links | BibTeX | Tags: AFM, Cantilever, MEMS, Sensors, Smart Structures @article{Ruppert2021, 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 for optical alignment. However, active microcantilevers are presently limited by the feedthrough between actuators and sensors, and by the cost associated with custom microfabrication. In this work, we propose a hybrid cantilever design with integrated piezoelectric actuators and a piezoresistive sensor fabricated from the silicon device layer without requiring an additional doping step. As a result, the design can be fabricated using a commercial five-mask microelectromechanical systems fabrication process. The theoretical piezoresistor sensitivity is compared with finite element simulations and experimental results obtained from a prototype device. The proposed approach is demonstrated to be a promising alternative to conventional microcantilever actuation and deflection sensing | |
2019 |
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5. | S. I. Moore; A. J. Fleming; Y. K. Yong Capacitive Instrumentation and Sensor Fusion for High-Bandwidth Nanopositioning Journal Article In: IEEE Sensor Letters, vol. 3, no. 8, pp. 2501503, 2019, ISBN: 2475-1472. Abstract | Links | BibTeX | Tags: Nanopositioning, Sensors @article{Moore2019, Precision capacitive sensing methods encode the measurement in a high frequency signal, which requires demodulation. To extract the measurement, the signal is observed over many cycles limiting the bandwidth of the sensor and introducing an undesirable phase lag. To address this limitation, this article outlines a design, which fuses the output of a standard modulated capacitive sensor and a charge amplifier, providing an instantaneous capacitive measurement whose bandwidth is only limited by the speed at which the electronics operate. | |
4. | M. G. Ruppert; B. S. Routley; A. J. Fleming; Y. K. Yong; G. E. Fantner Model-based Q Factor Control for Photothermally Excited Microcantilevers Proceedings Article In: Int. Conference on Manipulation, Automation and Robotics at Small Scales (MARSS), Helsinki, Finland, 2019, ISSN: 978-1-7281-0948-0. Abstract | Links | BibTeX | Tags: AFM, Multifrequency AFM, Sensors, Smart Structures, SPM, Vibration Control @inproceedings{Ruppert2019, Photothermal excitation of the cantilever for dynamic atomic force microscopy (AFM) modes is an attractive actuation method as it provides clean cantilever actuation leading to well-defined frequency responses. Unlike conventional piezo-acoustic excitation of the cantilever, it allows for model-based quality (Q) factor control in order to increase the cantilever tracking bandwidth for tapping-mode AFM or to reduce resonant ringing for high-speed photothermal offresonance tapping (PORT) in ambient conditions. In this work, we present system identification, controller design and experimental results on controlling the Q factor of a photothermally driven cantilever. The work is expected to lay the groundwork for future implementations for high-speed PORT imaging in ambient conditions. | |
3. | D. M. Harcombe; M. G. Ruppert; A. J. Fleming Modeling and Noise Analysis of a Microcantilever-based Mass Sensor Proceedings Article In: Int. Conference on Manipulation, Automation and Robotics at Small Scales (MARSS), Helsinki, Finland, 2019, ISSN: 978-1-7281-0948-0. Abstract | Links | BibTeX | Tags: AFM, Cantilever, MEMS, Sensors, Smart Structures @inproceedings{Harcombe2019, Nanomechanical devices have the potential for practical applications as mass sensors. In microcantilever based sensing, resonance frequency shifts are tracked by a phase-locked loop (PLL) in-order to monitor mass adsorption. A major challenge in minimizing the mass detection limit comes from the noise present in the system due to thermal, sensor and oscillator noise. There is numerical difficulty in simulating PLLs, as both low frequency phase estimates and high frequency mixing products need to be captured resulting in a stiff problem. By using linear system-theoretic modeling an in-depth analysis of the system is able to be conducted overcoming this issue. This provides insight into individual noise source propagation, dominant noise sources and possible ways to reduce their effects. The developed model is verified in simulation against the non-linear PLL, with each achieving low picogram sensitivity for a 100 Hz loop bandwidth and realistically modeled noise sources. | |
2. | M. G. Ruppert; S. I. Moore; M. Zawierta; A. J. Fleming; G. Putrino; Y. K. Yong Multimodal atomic force microscopy with optimized higher eigenmode sensitivity using on-chip piezoelectric actuation and sensing Journal Article In: Nanotechnology, vol. 30, no. 8, pp. 085503, 2019. Abstract | Links | BibTeX | Tags: AFM, Cantilever, MEMS, Multifrequency AFM, Piezoelectric Transducers and Drives, Sensors, Smart Structures, SPM @article{Ruppert2018b, 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. | |
2015 |
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1. | A. J. Fleming; B. S. Routley A Closed-Loop Phase-Locked Interferometer for Wide Bandwidth Position Sensing Journal Article In: Review of Scientific Instruments, vol. 86, pp. 115001(1-7), 2015. Abstract | Links | BibTeX | Tags: Nanopositioning, Optics, Sensors @article{J15f, This article describes a position sensitive interferometer with closed-loop control of the reference mirror. A calibrated nanopositioner is used to lock the interferometer phase to the most sensitive point in the interfer- ogram. In this conguration, large low-frequency movements of the sensor mirror can be detected from the control signal applied to the nanopositioner and high-frequency short-range signals can be measured directly from the photodiode. It is demonstrated that these two signals are complementary and can be summed to find the total displacement. The resulting interferometer has a number of desirable characteristics: it is optically simple, does not require polarization or modulation to detect the direction of motion, does not require fringe-counting or interpolation electronics, and has a bandwidth equal to that of the photodiode. Experimental results demonstrate the frequency response analysis of a high-speed positioning stage. The proposed instru- ment is ideal for measuring the frequency response of nanopositioners, electro-optical components, MEMs devices, Ultrasonic devices, and sensors such as surface acoustic wave detectors. |
2021 |
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6. | Active atomic force microscope cantilevers with integrated device layer piezoresistive sensors Journal Article In: Sensors & Actuators: A. Physical, vol. 319, pp. 112519, 2021, ISSN: 0924-4247. | |
2019 |
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5. | Capacitive Instrumentation and Sensor Fusion for High-Bandwidth Nanopositioning Journal Article In: IEEE Sensor Letters, vol. 3, no. 8, pp. 2501503, 2019, ISBN: 2475-1472. | |
4. | Model-based Q Factor Control for Photothermally Excited Microcantilevers Proceedings Article In: Int. Conference on Manipulation, Automation and Robotics at Small Scales (MARSS), Helsinki, Finland, 2019, ISSN: 978-1-7281-0948-0. | |
3. | Modeling and Noise Analysis of a Microcantilever-based Mass Sensor Proceedings Article In: Int. Conference on Manipulation, Automation and Robotics at Small Scales (MARSS), Helsinki, Finland, 2019, ISSN: 978-1-7281-0948-0. | |
2. | Multimodal atomic force microscopy with optimized higher eigenmode sensitivity using on-chip piezoelectric actuation and sensing Journal Article In: Nanotechnology, vol. 30, no. 8, pp. 085503, 2019. | |
2015 |
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1. | A Closed-Loop Phase-Locked Interferometer for Wide Bandwidth Position Sensing Journal Article In: Review of Scientific Instruments, vol. 86, pp. 115001(1-7), 2015. |