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@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},

url = {http://www.precisionmechatronicslab.com/wp-content/uploads/2021/01/J21a.pdf},

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}

}

@article{J20h,

title = {Position and force sensing using strain gauges integrated into piezoelectric bender electrodes},

author = {R. Seethaler and S. Z. Mansour and M. G. Ruppert and A. J. Fleming},

url = {http://www.precisionmechatronicslab.com/wp-content/uploads/2021/01/J20h-prepress-2.pdf},

doi = {10.1016/j.sna.2020.112416},

isbn = {0924-4247},

year  = {2020},

date = {2020-12-30},

journal = {Sensors and Actuators A: Physical},

pages = {112416},

abstract = {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 the actuator response with a linear model. The applications of this work include micro-grippers and pneumatic valves, which both require the measurement of deflection and load force. At present, this is achieved by external sensors. However, this work shows that these functions can be integrated into the actuator electrodes.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@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}

}