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@article{J18a,
title = {An Ultra-thin Monolithic XY Nanopositioning Stage Constructed from a Single Sheet of Piezoelectric Material},
author = {A. J. Fleming and Y. K. Yong},
url = {http://www.precisionmechatronicslab.com/wp-content/uploads/2017/09/Final.pdf},
year = {2017},
date = {2017-12-01},
journal = {IEEE/ASME Transactions on Mechatronics},
volume = {In Press},
abstract = {The article describes an XY nanopositioning stage constructed from flexures and actuators machined into a single sheet of piezoelectric material. Ultrasonic machining is used to remove piezoelectric material and create electrode features. The constructed device is 0.508mm thick and has a travel range of 8.8um in the X and Y axes. The first resonance mode occurs at 597Hz which makes the device suitable for a wide range of standard nanopositioning applications where cost and size are considerations. Experimental atomic force microscopy is performed using the proposed device as a sample scanner.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@inproceedings{C17f,
title = {Piezoelectric Bimorph Actuator with Integrated Strain Sensing Electrodes},
author = {S. Z. Mansour and R. J. Seethaler and Y. R. Teo and Y. K. Yong and A. J. Fleming},
url = {http://www.precisionmechatronicslab.com/wp-content/uploads/2017/08/Bender-paper.pdf},
year = {2017},
date = {2017-11-01},
booktitle = {IEEE Sensors},
address = {Glasgow, Scotland},
abstract = {This article describes a new method for estimating the tip displacement of piezoelectric benders. Two resistive strain gauges are fabricated within the top and bottom electrodes using an acid etching process. These strain gauges are employed in a half bridge electrical configuration to measure the surface resistance change, and estimate the tip displacement. Experimental validation shows a 1.1 % maximum difference between the strain sensor and a laser triangulation sensor.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}

@article{J17i,
title = {Existing Methods for Improving the Accuracy of Digital-to-Analog Converters},
author = {A. A. Eielsen and A. J. Fleming},
url = {http://www.precisionmechatronicslab.com/wp-content/uploads/2017/08/J17i.pdf},
year = {2017},
date = {2017-10-01},
journal = {Review of Scientific Instruments},
volume = {Accepted},
abstract = {The performance of digital-to-analog converters is principally limited by errors in the output voltage levels. Such errors are known as element mismatch and are quantified by the integral non-linearity. Element mismatch limits the achievable accuracy and resolution in high-precision applications as it causes gain and offset error, as well as harmonic distortion. In this article, five existing methods for mitigating the effects of element mismatch are compared: physical level calibration, dynamic element matching, noise-shaping with digital calibration, large periodic high-frequency dithering, and large stochastic high-pass dithering. These methods are suitable for improving accuracy when using digital-to-analog converters that use multiple discrete output levels to reconstruct time-varying signals. The methods improve linearity and therefore reduce harmonic distortion, and can be retrofitted to existing systems with minor hardware variations. The performance of each method is compared theoretically and confirmed by simulations and experiments. Experimental results demonstrate that three of the five methods provide significant improvements in the resolution and accuracy when applied to a general-purpose digital-to-analog converter. As such, these methods can directly improve performance in a wide range of applications including nanopositioning, metrology, and optics.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{J17h,
title = {A Review of Demodulation Techniques for Amplitude Modulation Atomic Force Microscopy},
author = {M. G. Ruppert and D. M. Harcombe and M. R. P. Ragazzon and S. O. R. Moheimani and A. J. Fleming},
url = {http://www.precisionmechatronicslab.com/wp-content/uploads/2017/07/m11627988-1.pdf},
year = {2017},
date = {2017-09-01},
journal = {Bellstein Journal of Nanotechnology},
volume = {In Press},
abstract = {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 amplitude 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 AFM experiments in constant height mode.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{J17j,
title = {Gradient-based optimization for efficient exposure planning in maskless lithography},
author = {O. T. Ghalehbeygi and A. G. Wills and B. S. Routley and A. J. Fleming},
url = {http://www.precisionmechatronicslab.com/wp-content/uploads/2017/09/J17j.pdf},
doi = {10.1117/1.JMM.16.3.033507},
year = {2017},
date = {2017-09-01},
journal = {Journal of Micro/Nanolithography, MEMS, and MOEMS},
volume = {16},
number = {3},
pages = {033507},
abstract = {Scanning laser lithography is a maskless method for exposing photoresist during semiconductor manufacturing. In this method, the energy of a focused beam is controlled while scanning the beam or substrate. With a positive photoresist material, areas that receive an exposure dosage over the threshold energy are dissolved during development. The surface dosage is related to the exposure profile by a convolution and nonlinear function, so the optimal exposure profile is nontrivial. A gradient-based optimization method for determining an optimal exposure profile, given the desired pattern and models of the beam profile and photochemistry, is described. This approach is more numerically efficient than optimal barrier-function-based methods but provides near-identical results. This is demonstrated through simulation and experimental lithography},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{J17g,
title = {An Algorithm for Transmitter Optimization in Electromagnetic Tracking Systems},
author = {M. N. Islam and A. J. Fleming},
url = {http://www.precisionmechatronicslab.com/wp-content/uploads/2017/05/07926412.pdf},
year = {2017},
date = {2017-08-30},
journal = {IEEE Transactions on Magnetics},
volume = {Accepted},
keywords = {},
pubstate = {published},
tppubtype = {article}
}