2021 Virtual Undergraduate Research Symposium

2021 Virtual Undergraduate Research Symposium

Assembly of Microparticles and Composite Materials Under Combined Electric and Magnetic Fields

Assembly of Microparticles and Composite Materials Under Combined Electric and Magnetic Fields

PROJECT NUMBER: 9 | AUTHOR: Benjamin Hanson, Physics

MENTOR: Ning Wu, Chemical and Biological Engineering

ABSTRACT

The method of assembling micro-robots from anisotropic particles is rich with potential, with drug delivery and colloidal assembly being a few of the many applications. The anisotropic nature of the robots allows for electric and magnetic fields to be converted into mechanical work and locomotion; the problem, however, arises in controlling the motion and direction of the robots. Electrohydrodynamic (EHD) flow is one of the most conventional methods of inducing particle propulsion. The limitation with this is that the propulsion is perpendicular to the applied electric field, while movement parallel to the electric field is random. To control this parallel movement, we have chosen a dual-system method, comparable to that of a car: a steering wheel for controlling the direction of motion, and an engine to control the magnitude of motion. A direct current magnetic field, created by a pair of Helmholtz coils, acts as the steering wheel, as the magnetic particles will quickly align their long axes with the field when in range. By manipulating this field, we can also manipulate the orientation of the robots. An alternating current electric field acts as the motor for the robots, as the frequency of the field controls the rotation speed of the structures, thus determining how quickly they propel perpendicular to the substrate. Using these combined fields, we can accurately direct large amounts of particles without the need for physical contact or refueling of any sort. Combined electric and magnetic field manipulation can pave the way for assembling anisotropic particles into even more complex and practical structures.

PRESENTATION

AUTHOR BIOGRAPHY

Benjamin Hanson is a Junior at the Colorado School of Mines, majoring in Engineering Physics, with a minor in Robotics and Intelligent Systems, and an Area of Special Interest in Space and Planetary Science Engineering. Benjamin’s research is in the field of Chemical and Biological Engineering, centering around the assembling of colloidal clusters, particularly on how these clusters move when under the effects of magnetic and electric fields. Benjamin has learned how to synthesize the particles used to create these clusters, use computational methods to analyze the movement, of the clusters, and has gained a better overall understanding about research and working in a lab. Benjamin would one day like to apply this research to studying microstructures and nanomaterials , with potential space applications like carbon nanotube elevator cables, more efficient rocket systems, lighter-weight solar sails, and nanosensors for improved spacesuits.

3 Comments

  1. This was really interesting! Based on your research, how does the synthesis of dimers effect the movement i.e. the difference in movements from Fe3O4 and SiO2/Fe3O4? Is there a large enough difference that would make certain materials more fit to be used in future experiments? What do you think is the significance of rotational frequency decay approaching a value proportional to the strength of the magnetic field? What do you think are the future applications from this knowledge?

    • Great question! There are actually numerous reasons for using the materials used to synthesize the dimers. For one, the ITO slides used during analysis have a slightly negative charge to them, so the SiO2 coating was added around the dimers to ensure that they would not stick to the substrate. Second, the electrohydrodynamic (EHD) flow, is really what controls the movement of these particles, and this flow is affected primarily by the zeta potential of these particles. Through experimentation, our group found that the specific synthesis of the dimers written about provided for the zeta potential of dimers that result in the most controllable and distinct movement. There is a possibility that different materials could make for better micromotors, but because of the ease of synthesis for these types of particles used, as well as the motion witnessed, we will continue to use the dimers listed. The significance of the rotational experiment is that with larger and larger magnetic fields, the dimers can rotate even faster, and since locomotion is proportional to rotation speed, it would mean they could move through whatever medium they are in faster. We hope to use these dimers for drug delivery as well as developing composite soft materials.

  2. This is fascinating! I really like the intersection between physics concepts and microscale engineering to produce something that’s extremely useful and applicable to many different fields.

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