Electromagnetic MEMS switch for MRI detuning circuits

Magnetic Resonance Imaging (MRI) is a noninvasive medical imaging technique due to its ability to produce high-contrast images of soft tissues without ionizing radiation. The latent principle involves transmitting radio waves at specific frequencies to alter the alignment of the hydrogen nuclei in a strong magnetic field, which emit signals during their return to alignment called relaxation which are captured and processed to create images. A critical aspect of MRI systems is the detuning process to optimize the signal-to-noise ratio (SNR), often using PIN diodes, with recent interest in Microelectromechanical Systems (MEMS) switches in this application. This thesis presents the design and development of an electromagnetically actuated double-clamped MEMS bridge for MRI detuning applications. The proposed MEMS bridge utilizes Lorentz force actuation, leveraging the MRI's magnetic field for operation, which simplifies the design and reduces power consumption. The device is fabricated using photolithography, physical vapor deposition, chemical vapor deposition, plasma etching and wet etching, with multiple prototypes created to ensure functionality. Performance parameters such as bandwidth, insertion loss, isolation, and switching time are targeted to meet MRI detuning requirements. This work aims to explore the possibility of achieving similar performance to a PIN diode in an MRI detuning circuit. The chapters include detailed analysis on the device's design, simulation, fabrication, testing processes, an evaluation of the results, potential improvements for future iterations and a literature review on MEMS switches in MRI systems.