| Summary: | 碩士 === 國立中興大學 === 機械工程學系所 === 101 === Magnetic field sensors play an important role in consuming electronic products and industry applications. For instance, a car has over ten magnetic sensors, and they apply in anti-lock braking system, ignition system and gas pedal control, etc. In addition, magnetic sensors are also applied in the global position system of smart phone. In the future, magnetic sensing technology is possible to use for spacing monitor such as monitor people in a building or traffic in the city. With rapid technological advancement, magnetic sensors have great development potential with its non-contact characteristic.
This study develops a magnetic sensor based on the Lorentz force. The sensor is composed of interdigitated electrodes and springs. The interdigitated electrodes are supported by the springs. The magnetic sensor is capacitive type, and the interdigitated electrodes are designed as a differential capacitance. When the magnetic sensor senses a magnetic field, the interdigitated electrodes actuated by the Lorentz force generate a change in displacement, resulting in the capacitance of the sensor varies. A sensing circuit is used to convert the capacitance variation of the sensor into the output voltage. The magnetic sensor was fabricated using the commercial TSMC (Taiwan Semiconductor Manufacturing Company) 0.35μm CMOS (complementary metal oxide semiconductor) process. A post-process was employed to release the suspended structure and reduce the residual stress of the structure. The post-process is compatible with the commercial CMOS process, so the sensor has a potential for integration with circuitry on chip. The experimental results showed that the magnetic sensor had a sensitivity of 8.4 V/T when applying a current of 40 mA.
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