2021 publications

Finetuning a single-blade sonic paper-cutter as an energy-saving sharpening instrument by Kudzai L. Shava, Carolline Hlakudi, Michiel Postema, and Craig S. Carlson was published in the Proceedings of the 2021 International Conference on Electrical, Computer and Energy Technologies (ICECET).
Constant usage and exposure to harsh environments results in a blade to become blunt. Two matching circuits were developed to improve the energy efficiency of an ultrasonic single-blade paper-cutting tool, whilst enhancing the sharpness of the blade. At an operating voltage of 10V peak, the cut made by the ultrasonic knife with a matching circuit was less tortuous than even an industrially cut edge, with a linearity of 61–63% compared to 59%, respectively.
This study was a collaborative work of the University of the Witwatersrand, Johannesburg, and Tampere University.

Comparison of paper edges from different cuts.
Comparison of paper edges from different cuts.

Sonic shrinking of Pickering-stabilised ultrasound contrast agent at a low acoustic amplitude by Nicole Anderton, Craig S. Carlson, Ryunosuke Matsumoto, Ri-ichiro Shimizu, Albert T. Poortinga, Nobuki Kudo, and Michiel Postema was published in the Proceedings of the 42nd Symposium on UltraSonic Electronics in 2021.
In a previous study, we determined that the presence of a core inside Pickering-stabilised microbubbles slightly hampered the oscillation amplitude compared to identical microbubbles without a core. The purpose of the present study is to determine whether the absence of a core negatively influences the stability of Pickering-stabilised microbubbles under sonication.
This study was a collaborative work of Tampere University, the University of the Witwatersrand, Johannesburg, Hokkaido University, and Eindhoven University of Technology.

Size distributions of microbubbles and antibubbles.
Size distributions of microbubbles and antibubbles.

Ultrasonic tablet disintegration for controlled digestion by Craig S. Carlson, Nicole Anderton, Antje Pohl, Andrew J. Smith, Nobuki Kudo, and Michiel Postema was published in the Proceedings of the 42nd Symposium on UltraSonic Electronics in 2021.
Controlled disintegration of tablets is relevant for chemical consistency checks of pharmaceutical tablets in vitro and for rapid gastric uptake of orally administered tablets in vivo. This feasibility study investigates if pulsed diagnostic brightness-mode ultrasound speeds up tablet disintegration.
This study was a collaborative work of the University of the Witwatersrand, Johannesburg, Tampere University, Ruhr-University Bochum, the University of Hull, and Hokkaido University.

Pill expansion and disintegration aided by ultrasound.
Pill expansion and disintegration aided by ultrasound.

The ultrasound-triggered explosion of an endoskeletal antibubble yields a predicable fragment size distribution by Nicole Anderton, Craig S. Carlson, Nobuki Kudo, Albert T. Poortinga, Michiel Postema was published in the 60th volume of the Japanese Journal of Applied Physics in 2021.
Recently, the first high-speed video of a fragmenting antibubble was published. Nonetheless, this fragmentation process was not fully understood. Owing to a recent study on fragmenting glass, we can now conclude that an antibubble under tensile stress undergoes an exponential fragmentation process.
This study was a collaborative work of Tampere University, the University of the Witwatersrand, Johannesburg, Hokkaido University, and Eindhoven University of Technology.

Fragment size distribution of an antibubble.
Fragment size distribution of an antibubble.

Deep impact of superficial skin inking: acoustic analysis of underlying tissue by Craig S. Carlson and Michiel Postema was published in the 2nd volume of BIO Integration in 2021.
Skin tattoos are a common decoration, but profound scientific study whether the presence of a skin tattoo alters the acoustic response from superficial tissue, and therefore from underlying tissue, was previously lacking. Any image aberrations caused by tattoo presence may have been thought negligible, yet empirically found artifacts in brightness-mode images of tattooed skin suggest otherwise. This study investigated the nature of these artifacts theoretically and experimentally in extremely simplified cases of perfectly flat and homogenous layered media and in tattooed pork.
This study was a collaborative work of the University of the Witwatersrand, Johannesburg and Tampere University.

Ultrasound images of a back tattoo.
Ultrasound images of a back tattoo.

Nucleation threshold of carbon black ultrasound contrast agent by Craig S. Carlson, Ryunosuke Matsumoto, Koji Fushino, Miryu Shinzato, Nobuki Kudo, and Michiel Postema was published in the 60th volume of the Japanese Journal of Applied Physics in 2021.
Black tattoo ink comprises hydrophobic carbon black nanoparticles. We hypothesised that black tattoo ink demonstrates transient dynamic activity in an ultrasound field.
This study was a collaborative work of the University of the Witwatersrand, Johannesburg, Hokkaido University, and Tampere University.

High-speed photography of nucleating tattoo ink.
High-speed photography of nucleating tattoo ink.

On the attenuation of ultrasound by pure black tattoo ink by Craig S. Carlson, Aurelié Deroubaix, Clement Penny, and Michiel Postema was published in the 112th volume of the SAIEE African Research Journal in 2021.
Most ultrasound contrast agents used in ultrasonic imaging comprise shell-encapsulated microbubbles, whose ingredients have been associated with adverse bioeffects. In this study, we investigated the nucleation behaviour of carbon black dispersion, whose hydrophobic nanoparticles are used intradermally as tattoo ink.
This study was a collaborative work of the University of the Witwatersrand, Johannesburg and Tampere University.

Transient scattering of black tattoo ink.
Transient scattering of black tattoo ink.

List of publications

2022

The full list of publications can be found on HAL.
A pre-2018 repository has been created at IPPT-PAN.