University of Twente Student Theses
Characterization of Frequency and Flow Response of Magnetically Actuated Swimming Millirobots with Asymmetric Helical Body
Boer, M.C.J. de (2024) Characterization of Frequency and Flow Response of Magnetically Actuated Swimming Millirobots with Asymmetric Helical Body.
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| Abstract: | Currently, one of the treatment methods for patients with acute proximal deep vein thrombosis is catheter-directed thrombolysis or mechanical thrombectomy. One of the factors that influence the complication rate of these treatments is the reachability of the thrombus. To overcome this increased complication risk, untethered magnetic swimming robots could be an addition to the mechanical treatment approach. In this paper, the swimming behaviour of such a robot with an asymmetrical helical body and varying magnetic volume was characterized by assessing frequency and flow response in-vitro in water. Here it became apparent that the robots had different swimming speeds for each orientation. Furthermore, linear relations between actuation frequency and flow and translational speed were found for flow responses for all measurements and for frequency responses up until the frequency where the robot could no longer overcome frictional forces (step-out frequency). Moreover, different magnet volumes showed different frequency responses with no direct relation between them. This gave more insight into other influencing factors such as magnetic force and frictional force. Additionally, using experimental data and previous research, step-out frequencies and maximum flow rates were estimated for the robots in blood. Besides, testing showed that the rotating permanent magnet which is used to actuate the robot is limited at 42 Hz. This was identified to be the limiting factor in achieving higher translational speeds. The last finding was that, when changing the swimming direction, the robot seemed to flip randomly, especially when further away from the rotating permanent magnet. For future research, it is essential to test the asymmetrical design in blood as well. By doing this, the accuracy of the estimations of the robot’s performance in blood can be assessed. This could allow direct translation of test results in water setups to outcomes in blood. To overcome higher flow rates, which would be necessary for possible future clinical applications, the maximum frequency of the actuator should be increased. Furthermore, to counter the flipping of the robot, a different control method where the actuator is no longer stationary and/or a change in design towards a symmetrical body is recommended. |
| Item Type: | Essay (Bachelor) |
| Faculty: | ET: Engineering Technology |
| Subject: | 33 physics, 50 technical science in general |
| Programme: | Biomedical Technology BSc (56226) |
| Link to this item: | https://purl.utwente.nl/essays/98527 |
| Export this item as: | BibTeX EndNote HTML Citation Reference Manager |
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