A MEMS-based magnetic field sensor with simple resonant structure and linear electrical response

• A MEMS-based magnetic field sensor with simple structure was developed.
• The sensor structure was fabricated using a standard bulk micromachining process.
• The sensor oscillates at its first resonant frequency without a vacuum packaging.
• Analytical and FEM models were developed to predict the sensor performance.
• The sensor has small size, low power consumption, and linear electrical response.

We present a microelectromechanical system (MEMS)-based magnetic field sensor with simple structural configuration, low power consumption, and linear electrical response. This sensor operates with Lorentz force and uses piezoresistive sensing. Its resonant silicon structure consists of a perforated plate (472 × 300 × 15 μm), four flexural beams (18 × 15 × 15 μm), two support beams (60 × 36 × 15 μm), and an aluminum loop (9 × 2 μm cross-section), which are fabricated using a standard bulk micromachining process. The sensor works at its first seesaw resonant frequency without a vacuum packaging. Analytical and finite element method (FEM) models are developed to predict the mechanical behavior of the sensor structure considering the main damping sources. The experimental seesaw resonant frequency and quality factor of the sensor are 100.7 kHz and 419.6, respectively. The sensor has a linear electrical response and its detection range can be easily adjusted. For a DC bias voltage (Vin) of 3 V and a bandwidth of 240 Hz, the sensor has sensitivity, resolution, and power consumption of 230 mV⋅T–1, 2.5 μT, and 12 mW, respectively. This sensor could be used in non-destructive magnetic testing for monitoring geometrical defects and corrosion of ferromagnetic materials.

Figure optionsDownload as PowerPoint slide