
Thesis Format
Monograph
Degree
Master of Engineering Science
Program
Electrical and Computer Engineering
Supervisor
Sabarinathan, Jayshri
Abstract
The miniaturization of highly sensitive and accurate microsensors is crucial for advancing modern sensing technologies with the goal of integrating increasingly complex circuits onto compact devices, such as smart phones and wearables. In this work, a Lorentz force magnetometer was designed based on the concept of a photonic crystal directional coupler (PCDC) for magnetic field sensing perpendicular (out-of-plane) to the chip surface. Built on the Silicon-On-Insulator platform, a custom post-processing recipe was developed to fabricate the electrically controlled optomechanical device at the micron scale. A modified version of a Helmholtz coil was also designed and constructed to facilitate precise out-of-plane magnetic field measurements to characterize the sensor performance. The resulting magnetometer designed here is highly sensitive with a detection limit of 33nT.A/rtHz at 2.7MHz with a footprint area of only 115um x 161um making it highly effective for applications requiring out-of-plane magnetic field detection.
Summary for Lay Audience
Commercial sensors have been constantly shrinking in size all the way to the micrometer scale and smaller. This trajectory has enabled higher complexity circuits to enhance everyday life, offering consumers faster and more powerful devices while keeping them portable for integration with Internet-of-Things (IoT), smartphones, and wearables. The work presented in this thesis is one such device that is 115um x 161um in area and used as a microsensor.
Specifically, the sensor developed is based on a Photonic Crystal Directional Coupler (PCDC) that can detect magnetic fields using optomechanical sensing, a sensing method that manipulates light along with mechanical motion. Magnetometers or magnetic sensors have had a wide range of applications in many industries such as healthcare, automotive, aerospace, consumer electronics, and environmental monitoring.
Manufacturing these extremely small devices comes with their own set of challenges; the work here included developing a process that allows for the creation of these electrically controlled optomechanical devices. To ensure that the devices have been designed and developed properly, experimental testing is also required.
A modified version of a small-scale electromagnetic coil, called a Helmholtz coil, was made in order to generate variable magnetic fields in a laboratory setting. This coil was then integrated into a hybrid optical-electrical measurement setup for testing of the PCDC magnetometer.
Recommended Citation
Siquioco, Lance Ferdinand Sotto, "Photonic Crystal Lorentz Force Magnetometer for Out-of-Plane Magnetic Field Sensing" (2024). Electronic Thesis and Dissertation Repository. 10616.
https://ir.lib.uwo.ca/etd/10616