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@article{Ruppert2022,

title = {Experimental Analysis of Tip Vibrations at Higher Eigenmodes of QPlus Sensors for Atomic Force Microscopy},

author = {M. G. Ruppert and D. Martin-Jimenez and Y. K. Yong and A. Ihle and A. Schirmeisen and A. F. Fleming; D. Ebeling},

url = {http://www.precisionmechatronicslab.com/wp-content/uploads/2022/01/2020_J_QPlus_Analysis_v12_final.pdf},

doi = {https://doi.org/10.1088/1361-6528/ac4759},

year  = {2021},

date = {2021-12-31},

urldate = {2022-12-31},

journal = {Nanotechnology},

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 sample, 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.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {3D-printed omnidirectional soft pneumatic actuators: Design, modeling and characterization},

author = {M. S. Xavier and C. D. Tawk and Y. K. Yong and A. J. Fleming},

doi = {https://doi.org/10.1016/j.sna.2021.113199},

year  = {2021},

date = {2021-12-25},

urldate = {2021-12-25},

journal = {Sensors and Actuators: A. Physical },

keywords = {},

pubstate = {forthcoming},

tppubtype = {article}

}

@article{Omidbeike2021,

title = {Five-Axis Bimorph Monolithic Nanopositioning Stage: Design, Modeling, and Characterization},

author = {M. Omidbeike and S. I. Moore and Y. K. Yong and A. J. Fleming},

doi = {https://doi.org/10.1016/j.sna.2021.113125},

year  = {2021},

date = {2021-09-16},

urldate = {2021-09-16},

journal = {Sensors and Actuators A: Physical},

volume = {In press},

abstract = {The article describes the design and modeling of a five-axis monolithic nanopositioning stage constructed from a bimorph piezoelectric sheet. Six-axis motion is also possible but requires 16 amplifier channels rather than 8. The nanopositioner is ultra low profile with a thickness of 1 mm. Analytical modeling and finite-element-analysis accurately predict the experimental performance. The stage was conservatively driven with 33% of the maximum voltage, which resulted in an X and Y travel range of 6.22 μm and 5.27 μm respectively; a Z travel range of 26.5 μm; and a rotational motion of 600 μrad and 884 μrad about the X and Y axis respectively. The first resonance frequency occurs at 883 Hz in the Z axis. Experimental atomic force microscopy is performed using the proposed device as a sample scanner.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{J21d,

title = {Design and Control of Pneumatic Systems for Soft Robotics: a Simulation Approach},

author = {M. S. Xavier and A. J. Fleming and Y. K. Yong},

url = {http://www.precisionmechatronicslab.com/wp-content/uploads/2021/06/J21d-Prepress.pdf},

doi = {10.1109/LRA.2021.3086425},

year  = {2021},

date = {2021-06-04},

journal = {IEEE Robotics and Automation Letters},

volume = {Early Access},

abstract = {Pressure control plays a major role in the overall performance of fluid-driven soft robots. Due to the increasing demand for higher speed actuation and precision, a need exists for a practical design methodology that converts actuator performance specifications to a set of minimum pneumatic specifications, such as receiver volume and pressure, and valve conductance. This article presents a systematic parameter selection approach for pneumatic soft robotic systems by taking into consideration the desired closed-loop pressure responses. The two controllers under evaluation here are the PI controller with anti-windup and the on-off controller with hysteresis. Simulations are developed within Simscape Fluids to evaluate the effect of physical components and controller parameters on the actuator performance. The proposed parameter selection procedures are then applied on three soft actuators and their closed-loop pressure responses are experimentally evaluated. The measured pressure responses are in close agreement with the simulations and satisfy the rise time specifications.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}