Date Thesis Awarded
Honors Thesis -- Open Access
Bachelors of Science (BS)
This thesis describes research to investigate the electromagnetic manipulation of microspheres and microrings. The work consists of three main thrusts: 1) the use of an electric field gradient to move dielectric microspheres, 2) the use of an AC magnetic field to move a conducting ring, and 3) the preparation of substrates for a microwave atom chip. The electrostatic movement of dielectric polyethylene microspheres was observed and recorded with a CCD imaging system. The microspheres were suspended in various liquids and placed on top of a microstrip transmission line, which consists of a conducting copper trace separated from a ground plate by an FR4 dielectric substrate. 5 kV was applied to the conducting trace. Some microspheres acted as weak field seekers and were repelled from the trace, as predicted by theoretical calculations, while others acted as strong field seekers and were attracted to the trace. Electromagnetic simulations generated using the software FEKO indicate that the dipole force experienced by the microspheres should be several orders of magnitude higher than experimentally observed. Further research is necessary to reconcile the difference between theoretical calculations and observed microsphere behavior, but it seems likely that competing electrokinetic effects impede the movement of microspheres. Several microrings were constructed and placed in the vicinity of an alternating magnetic field. Theoretical calculations were performed to estimate: a) the cutoff frequency at which microrings act inductively and b) the force experienced by microrings. No microring movement was observed in preliminary experiments, but further experiments were conducted to find the cutoff frequency using a multi-turn pickup coil and the magnetic field generated by a solenoid.
Beling, Andrew John, "Progress Towards Electromagnetic Manipulation and Trapping of Micro-particles" (2021). Undergraduate Honors Theses. William & Mary. Paper 1707.