Scanning Probe Microscopy
Probe Based Lithography
Probe based lithography involves creating nanometer sized features from photoresist and metal on conducting and semiconducting substrates. Near field optical, electrical and thermal fields are employed in combination with evaporation, etching and electroplating to provide high-speed alternatives for mask-less nanofabrication.
Nanopositioning
A nanopositioner is a electromechanical device for moving objects in three dimensions with atomic, or sub-atomic resolution. Nanopositioners are employed in applications such as imaging, fabrication and optics. This field encompasses mechanical design, sensor design, and control theory. More details.
Electroactive Optics
Piezoelectric actuators can be combined with mirrors, lenses and objectives to actively control the path and properties of an optical field or laser beam. High speed electro-optics are required for precision lasers, maskless lithography, and microscopy.
Precision Sensors
This project aims to study the fundamental limitations of capacitive, optical and magnetic position sensors. New techniques are under development to provide sub-atomic resolution over extremely wide bandwidth.
Biomedical Devices
An endoscopic pill robot is being developed for noninvasive imaging and intervention. The robot can be swallowed and includes power transmission, 6-Dimensional localization, and locomotion.
Piezo Actuators and Amplifiers

Piezo bender actuator with integrated 200V power electronics
Piezo Robotics
Due to their compact size and high efficiency, piezoelectric actuators are ideal for micro-actuation in bio-inspired robotics. This project is developing actuators and mechanics for a piezoelectric dragon-fly robot.
Ruppert, M G; Fleming, A J; Yong, Y K Active atomic force microscope cantilevers with integrated device layer piezoresistive sensors Journal Article In: Sensors & Actuators: A. Physical, 2021. @article{Ruppert2021, title = {Active atomic force microscope cantilevers with integrated device layer piezoresistive sensors}, author = {M. G. Ruppert and A. J. Fleming and Y. K. Yong}, doi = {10.1016/j.sna.2020.112519}, year = {2021}, date = {2021-01-19}, journal = {Sensors & Actuators: A. Physical}, abstract = {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}, keywords = {}, pubstate = {published}, tppubtype = {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 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 ![]() |
Xavier, M S; Fleming, A J; Yong, Y K Finite Element Modeling of Soft Fluidic Actuators: Overview and Recent Developments Journal Article In: Finite Element Modeling of Soft Fluidic Actuators: Overview and Recent Developments, pp. 2000187, 2020. @article{Xavier2020, title = {Finite Element Modeling of Soft Fluidic Actuators: Overview and Recent Developments}, author = {M. S. Xavier and A. J. Fleming and Y. K. Yong}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/aisy.202000187http://www.precisionmechatronicslab.com/wp-content/uploads/2020/10/document.pdf}, doi = {10.1002/aisy.202000187}, year = {2020}, date = {2020-10-30}, journal = {Finite Element Modeling of Soft Fluidic Actuators: Overview and Recent Developments}, pages = {2000187}, abstract = {Many soft robots are composed of soft fluidic actuators that are fabricated from silicone rubbers and use hydraulic or pneumatic actuation. The strong nonlinearities and complex geometries of soft actuators hinder the development of analytical models to describe their motion. Finite element modeling provides an effective solution to this issue and allows the user to predict performance and optimize soft actuator designs. Herein, the literature on a finite element analysis of soft actuators is reviewed. First, the required nonlinear elasticity concepts are introduced with a focus on the relevant models for soft robotics. In particular, the procedure for determining material constants for the hyperelastic models from material testing and curve fitting is explored. Then, a comprehensive review of constitutive model parameters for the most widely used silicone rubbers in the literature is provided. An overview of the procedure is provided for three commercially available software packages (Abaqus, Ansys, and COMSOL). The combination of modeling procedures, material properties, and design guidelines presented in this article can be used as a starting point for soft robotic actuator design.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Many soft robots are composed of soft fluidic actuators that are fabricated from silicone rubbers and use hydraulic or pneumatic actuation. The strong nonlinearities and complex geometries of soft actuators hinder the development of analytical models to describe their motion. Finite element modeling provides an effective solution to this issue and allows the user to predict performance and optimize soft actuator designs. Herein, the literature on a finite element analysis of soft actuators is reviewed. First, the required nonlinear elasticity concepts are introduced with a focus on the relevant models for soft robotics. In particular, the procedure for determining material constants for the hyperelastic models from material testing and curve fitting is explored. Then, a comprehensive review of constitutive model parameters for the most widely used silicone rubbers in the literature is provided. An overview of the procedure is provided for three commercially available software packages (Abaqus, Ansys, and COMSOL). The combination of modeling procedures, material properties, and design guidelines presented in this article can be used as a starting point for soft robotic actuator design. ![]() |
Fleming, A J; Ruppert, M G; Routley, B S; McCourt, L Overcoming the Limitations of Tip Enhanced Raman Spectroscopy with Intermittent Contact AFM Conference 8th Multifrequency AFM Conference, Madrid, Spain, 2020. @conference{Fleming2020, title = {Overcoming the Limitations of Tip Enhanced Raman Spectroscopy with Intermittent Contact AFM}, author = {A. J. Fleming and M. G. Ruppert and B. S. Routley and L. McCourt}, year = {2020}, date = {2020-10-27}, booktitle = {8th Multifrequency AFM Conference}, address = {Madrid, Spain}, abstract = {Tip enhanced Raman spectroscopy (TERS) is a promising technique for mapping the chemical composition of surfaces with molecular scale. However, current TERS methods are limited by a number of issues including high tip-sample forces, high laser power, low topographical resolution, and short probe lifetime. As a result, TERS methods are best suited to robust samples that can tolerate high optical intensity. To overcome these issues and extend the application of TERS to delicate samples, a number of new probes andimaging modes are in development at the University of Newcastle. This talk will provide an overview of these methods and present preliminary results, including new methods for optical probe optimization and fabrication, and a new dynamic-mode AFM method to reduce contact forces and applied laser power.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Tip enhanced Raman spectroscopy (TERS) is a promising technique for mapping the chemical composition of surfaces with molecular scale. However, current TERS methods are limited by a number of issues including high tip-sample forces, high laser power, low topographical resolution, and short probe lifetime. As a result, TERS methods are best suited to robust samples that can tolerate high optical intensity. To overcome these issues and extend the application of TERS to delicate samples, a number of new probes andimaging modes are in development at the University of Newcastle. This talk will provide an overview of these methods and present preliminary results, including new methods for optical probe optimization and fabrication, and a new dynamic-mode AFM method to reduce contact forces and applied laser power. ![]() |
Ruppert, M G; Harcombe, D M; Fleming, A J Traditional and Novel Demodulators for Multifrequency Atomic Force Microscopy Conference 8th Multifrequency AFM Conference, Madrid, Spain, 2020. @conference{Ruppert2020b, title = {Traditional and Novel Demodulators for Multifrequency Atomic Force Microscopy}, author = {M. G. Ruppert and D. M. Harcombe and A. J. Fleming}, year = {2020}, date = {2020-10-27}, booktitle = {8th Multifrequency AFM Conference}, address = {Madrid, Spain}, abstract = {A number of multifrequency atomic force microscopy (MF-AFM) methods make use of the excitation and detection of higher harmonics of the fundamental frequency, higher flexural eigenmodes or intermodulation products generated by the non-linear tip-sample force [1]. Schematically, these methods are depicted in Figure 1(a) where the main difference is the resulting spacing and amplitude of the frequency components in the generated spectrum shown in Figure 1(b). Regardless of which particular MF-AFM method is employed, each requires a demodulator to obtain amplitude and phase to form observables for the characterization of nanomechanical sample information. Since high-speed non-synchronous demodulators such as the peak-hold method, peak detector and RMS-to-DC converter are incompatible with MF-AFM [2], there is a need for high-bandwidth demodulation techniques capable of estimating multiple frequencies at once while maintaining robustness against unwanted frequency components [3]. In this talk, the performance of traditional and recently proposed demodulators for multifrequency atomic force microscopy is assessed experimentally. 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 sampling rate of 1.5 MHz. The metrics for comparison include implementation complexity, 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.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } A number of multifrequency atomic force microscopy (MF-AFM) methods make use of the excitation and detection of higher harmonics of the fundamental frequency, higher flexural eigenmodes or intermodulation products generated by the non-linear tip-sample force [1]. Schematically, these methods are depicted in Figure 1(a) where the main difference is the resulting spacing and amplitude of the frequency components in the generated spectrum shown in Figure 1(b). Regardless of which particular MF-AFM method is employed, each requires a demodulator to obtain amplitude and phase to form observables for the characterization of nanomechanical sample information. Since high-speed non-synchronous demodulators such as the peak-hold method, peak detector and RMS-to-DC converter are incompatible with MF-AFM [2], there is a need for high-bandwidth demodulation techniques capable of estimating multiple frequencies at once while maintaining robustness against unwanted frequency components [3]. In this talk, the performance of traditional and recently proposed demodulators for multifrequency atomic force microscopy is assessed experimentally. 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 sampling rate of 1.5 MHz. The metrics for comparison include implementation complexity, 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. ![]() |
McCourt, L; Ruppert, M G; Routley, B S; Indirathankam, S; Fleming, A J A comparison of gold and silver nanocones and geometry optimisation for tip-enhanced microscopy Journal Article In: Journal of Raman Spectroscopy, pp. 1-9, 2020. @article{McCourt2020, title = {A comparison of gold and silver nanocones and geometry optimisation for tip-enhanced microscopy}, author = {L. McCourt and M. G. Ruppert and B. S. Routley and S. Indirathankam and A. J. Fleming}, url = {http://www.precisionmechatronicslab.com/wp-content/uploads/2020/09/J20e.pdf}, doi = {https://doi.org/10.1002/jrs.5987}, year = {2020}, date = {2020-08-24}, journal = {Journal of Raman Spectroscopy}, pages = {1-9}, abstract = {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 parameter sets or used a performance metric other than localised electric field enhancement. In this article, the optical responses for a range of nanocone geometries are simulated for excitation wavelengths ranging from 400 to 1000 nm. Performance is evaluated by measuring the electric field enhancement at the sample surface with a resonant illumination wavelength. These results are then used to determine empirical models and derive optimal nanocone geometries for a particular illumination wavelength and tip material. This article concludes that gold nanocones are expected to provide similar performance to silver nanocones at red and nearinfrared wavelengths, which is consistent with other results in the literature. In this article, 633 nm is determined to be the shortest usable illumination wavelength for gold nanocones. Below this limit, silver nanocones will provide superior enhancement. The use of gold nanocone probes is expected to dramatically improve probe lifetime, which is currently measured in hours for silver coated probes. Furthermore, the elimination of passivation coatings is expected to enable smaller probe radii and improved topographical resolution.}, keywords = {}, pubstate = {published}, tppubtype = {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 parameter sets or used a performance metric other than localised electric field enhancement. In this article, the optical responses for a range of nanocone geometries are simulated for excitation wavelengths ranging from 400 to 1000 nm. Performance is evaluated by measuring the electric field enhancement at the sample surface with a resonant illumination wavelength. These results are then used to determine empirical models and derive optimal nanocone geometries for a particular illumination wavelength and tip material. This article concludes that gold nanocones are expected to provide similar performance to silver nanocones at red and nearinfrared wavelengths, which is consistent with other results in the literature. In this article, 633 nm is determined to be the shortest usable illumination wavelength for gold nanocones. Below this limit, silver nanocones will provide superior enhancement. The use of gold nanocone probes is expected to dramatically improve probe lifetime, which is currently measured in hours for silver coated probes. Furthermore, the elimination of passivation coatings is expected to enable smaller probe radii and improved topographical resolution. ![]() |