Single-crystal diamond microelectromechanical resonator integrating with magneto-strictive galfenol film for magnetic sensor

Single-crystal diamond (SCD) is a promising material for micro-electromechanical system (MEMS) devices to achieve high performance and reliability due to its prominent mechanical and physical properties. However, the application of SCD MEMS has not been practically achieved due to the lack of device concept for SCD MEMS. Here, the SCD MEMS resonator based magnetic sensor is successfully realized with integrating of a large magneto-strictive galfenol film on SCD mechanical resonator with high performance. It is concluded that SCD provides a suitable substrate for galfenol film with excellent magnetic properties. Along with the high-quality factor of the SCD MEMS resonator, a high magnetic field sensitivity of 4.83 Hz/mT and an extremely low detectable force of 2.14 × 10⁻¹² N are achieved. Based on the experimental results, the estimated minimum detectable force, magnetic field and energy reach 1.76 × 10⁻¹⁴ N, 1.42 × 10⁻¹⁰ T and 8.4 × 10⁻²⁹ J. The successful fabrication of SCD MEMS magnetic sensor provides a promising strategy for broadening the application of SCD MEMS with merits super to other ones, such as nanoscale to microscale spatial resolution, wide-range magnetic field sensing, high sensitivity, high temperature operation, and facile integration with CMOS.