Special Public PhD Thesis Defense Talk

Microdevices for Locomotion in Complex Biological Fluids (Special Public PhD Thesis Defense Talk)

  • Date: Mar 16, 2016
  • Time: 10:00 - 11:30
  • Speaker: Tian Qiu
  • Location: MPI IS Stuttgart and MPI IS Tübingen
  • Room: Hörsaal 5H 7
  • Host: Prof. Dr. Peer Fischer
  • Contact: OfficeFischer@is.mpg.de
Special Public PhD Thesis Defense Talk
The overall goal of my PhD thesis is to develop microdevices that are capable of actively propelling themselves through and performing tasks in complex biological fluids. Two major challenges are encountered: the complex fluidic environment and the small length scale. I first show that we managed to exploit the complex rheology of biological (non-Newtonian) fluids to build and operate the first symmetric microswimmer, a “micro-scallop”. The work suggests that simple actuation schemes can after all be used for propulsion in biological fluids. The second challenge is the small size of microdevices which severely limits the choice of available miniaturized actuators. To address the challenge of powering untethered microdevices, a novel bubble array streaming surface actuator is developed. Under ultrasonic excitation, the oscillation of micro gas bubbles results in acoustic streaming and provides a propulsive force that drives the device. The actuator operates as an end-effector of a miniaturized endoscope, which has a cross-sectional side length of only 1 mm, smaller than endoscopes currently in use. Active cystoscopy is successfully performed with the actuator inside a rabbit bladder. It is envisioned that miniaturized medical instruments and micro-robots can benefit from the wireless actuation schemes presented in this talk.
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