04 Fakultät Energie-, Verfahrens- und Biotechnik

Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/5

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    Acoustic streaming‐induced multimodal locomotion of bubble‐based microrobots
    (2023) Mahkam, Nima; Aghakhani, Amirreza; Sheehan, Devin; Gardi, Gaurav; Katzschmann, Robert; Sitti, Metin
    Acoustically‐driven bubbles at the micron scale can generate strong microstreaming flows in its surrounding fluidic medium. The tunable acoustic streaming strength of oscillating microbubbles and the diversity of the generated flow patterns enable the design of fast‐moving microrobots with multimodal locomotion suitable for biomedical applications. The acoustic microrobots holding two coupled microbubbles inside a rigid body are presented; trapped bubbles inside the L‐shaped structure with different orifices generate various streaming flows, thus allowing multiple degrees of freedom in locomotion. The streaming pattern and mean streaming speed depend on the intensity and frequency of the acoustic wave, which can trigger four dominant locomotion modes in the microrobot, denoted as translational and rotational, spinning, rotational, and translational modes. Next, the effect of various geometrical and actuation parameters on the control and navigation of the microrobot is investigated. Furthermore, the surface‐slipping multimodal locomotion, flow mixing, particle manipulation capabilities, the effective interaction of high flow rates with cells, and subsequent cancerous cell lysing abilities of the proposed microrobot are demonstrated. Overall, these results introduce a design toolbox for the next generation of acoustic microrobots with higher degrees of freedom with multimodal locomotion in biomedical applications.
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    Immune cell‐based microrobots for remote magnetic actuation, antitumor activity, and medical imaging
    (2024) Dogan, Nihal Olcay; Suadiye, Eylül; Wrede, Paul; Lazovic, Jelena; Dayan, Cem Balda; Soon, Ren Hao; Aghakhani, Amirreza; Richter, Gunther; Sitti, Metin
    Translating medical microrobots into clinics requires tracking, localization, and performing assigned medical tasks at target locations, which can only happen when appropriate design, actuation mechanisms, and medical imaging systems are integrated into a single microrobot. Despite this, these parameters are not fully considered when designing macrophage‐based microrobots. This study presents living macrophage‐based microrobots that combine macrophages with magnetic Janus particles coated with FePt nanofilm for magnetic steering and medical imaging and bacterial lipopolysaccharides for stimulating macrophages in a tumor‐killing state. The macrophage‐based microrobots combine wireless magnetic actuation, tracking with medical imaging techniques, and antitumor abilities. These microrobots are imaged under magnetic resonance imaging and optoacoustic imaging in soft‐tissue‐mimicking phantoms and ex vivo conditions. Magnetic actuation and real‐time imaging of microrobots are demonstrated under static and physiologically relevant flow conditions using optoacoustic imaging. Further, macrophage‐based microrobots are magnetically steered toward urinary bladder tumor spheroids and imaged with a handheld optoacoustic device, where the microrobots significantly reduce the viability of tumor spheroids. The proposed approach demonstrates the proof‐of‐concept feasibility of integrating macrophage‐based microrobots into clinic imaging modalities for cancer targeting and intervention, and can also be implemented for various other medical applications.