<p>The diminutive size of
microrobots makes them advantageous for minimally invasive operations and
precise, localized treatment. One such application is aiding in localized drug delivery
for colorectal cancer as microrobots could offer reduced patient trauma, lower
risk of side effects, and higher drug retention rates. In this study, we
evaluate the abilities of a magnetic microrobot in a variety of conditions
using a high frequency ultrasound system. Under the influence of an external
rotating magnetic field, the microrobot tumbles end-over-end to propel itself
forward. Cytotoxicity tests demonstrated the constituent materials of
polydimethylsiloxane (PDMS) and SU-8 were nontoxic to murine fibroblasts. Then,
we quantified robot locomotion in an <i>ex vivo</i> porcine colon, testing the
materials, the tumbling orientation, and three magnet rotation frequencies.
Significant differences were found between materials and tumbling orientation,
revealing that SU-8 lengthwise microrobots were the fastest with an average
velocity of 2.12±0.25mm/s at a frequency of 1Hz. With this finding, the next
tests were completed at 1Hz frequency with SU-8 lengthwise microrobots. We used
<i>in vitro</i> agarose gels to maneuver the
robot through a variety of trajectories, tested the microrobots <i>in situ</i> and <i>in vivo</i> murine colons as well. Average velocities were calculated
for all tests with the <i>in vivo</i> murine
colon tests finding an average velocity of 2.07±0.05mm/s. Finally, the
microrobots were coated with a fluorescein payload and were shown to release a
payload over a one-hour time period. These findings suggest microrobots are
promising for targeted drug delivery and other <i>in vivo</i> biomedical applications.</p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/12269591 |
| Date | 08 May 2020 |
| Creators | Elizabeth E Niedert (8787980) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/High_Frequency_Ultrasound_Imaging_of_Tumbling_Magnetic_Microrobots/12269591 |
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