UCLA

This dissertation focuses on the design, fabrication, and testing of two microelectromechanical (MEMS) devices that utilize ferroic materials for applications in biomedical engineering: a magnetic single-cell capture-and-release platform and a 400 MHz multiferroic implantable antenna. Ferroic materials are a class of materials that exhibit spontaneous polarization, magnetic moment, or mechanical strain. These unique electrical, magnetic, and mechanical properties make them desirable for various applications. For instance, in electronics, ferroic materials are used in various devices such as sensors, actuators, and data storage devices. In recent years, a large amount of research has been conducted on the miniaturization of ferroic devices due to the benefits of having a small form factor. Miniaturized devices often have improved performance, reduced costs, and increased portability. In the biomedical industry, miniaturization has led to developing smaller and more compact medical devices such as implantable sensors, drug delivery systems, and wearable monitoring devices. These devices are more convenient for patients and provide a more cost-effective and accessible solution to healthcare challenges. Chapter one of this dissertation introduces the concept of ferroic materials and the mechanism behind their properties. I first present and discuss ferromagnetic materials and the physics behind them. Then I discuss their applications and, more specifically, their application in the biomedical industry. I then briefly cover the physics and applications of ferroelectric and ferroelastic materials. To conclude this chapter, I discuss the emerging field of multiferroic composites and their applications. The second chapter explores the creation of our platform for capturing and releasing single cells using magnetism. The chapter starts by highlighting the significance of cell sorting and the necessity for effective single-cell capture, and the importance of deterministic single-cell release. Next, a comprehensive examination of existing devices aimed at high-throughput single-cell capture and manipulation is conducted, along with an evaluation of their drawbacks. Our platform is then introduced, outlining its design and how it overcomes the limitations of previous devices. The theoretical validation of each component is also described and performed using finite element and finite difference methods. The microfabrication process used to make our platform is then outlined. Next, I describe how we experimentally verified the platform’s capability to magnetize and demagnetize individual capture sites using magnetic force microscopy. I then present the results from our experiments, where we demonstrate the capture and deterministic release of superparamagnetic beads and then successfully demonstrate the capture of single T-cells and their subsequent individual release. Chapter three addresses the development of our 400 MHz multiferroic implantable antenna. This chapter begins with a brief introduction to implantable antennas and the challenges they currently face as a technology. I then describe multiferroic antenna technology and its benefits and how it can address the challenges described previously. These benefits include its ability to be miniaturized without compromising efficiency and its compatibility with implantable antennas. Next, I describe our multiferroic antenna design and its operation principle. Given that my work primarily revolved around the microfabrication of this device, the majority of the rest of this chapter revolves around the microfabrication process and the challenges that were faced during the design of this fabrication process. Following this, I show some fabricated devices and discuss the experimental material characterization of the different components of the antennas. In closing, I present the experimental results from the fabricated antennas. In particular, I discuss the S11 reflection coefficient and the S21 transmission coefficient response as they vary with input signal frequency. Lastly, the dissertation concludes with a summary of both projects discussed, and I outline the potential future work that could be conducted to further improve these devices.