Smart resonant micro-sensor and micro-actuator: high-performance, wide range bi-axial magnetic sensitive/ insensitive micro-device for multifunctional sensing applications.

With the rapid development of intelligent and autonomous systems, such as wearable health monitoring and advanced manufacturing robots, there is a growing demand for the development of advanced, miniaturized smart sensors and actuator systems. In this context, a single microdevice with hybrid functionality as both a sensor and actuator demonstrates excellent performance across diverse applications, holds significant promise. Herein, we present a proof-of-concept for a high-performance bi-directional Lorentz force magnetometer and actuator, implemented within a single microelectromechanical system (MEMS) device. Moreover, the device demonstrates insensitivity to magnetic fields, making it highly suitable for applications that require anti-crossing behavior in magnetic environments. The design is based on a clamped-guided curved microresonator connected to straight and V-shaped beams of micro-actuators. The operation of the proposed device relies on the flexibility to control the applied electrothermal excitation in different ways, offering smart thermal actuation and dynamic sensing mechanisms. Furthermore, the proposed technique allows tuning of the first symmetric mode, achieving either a high or low frequency shift based on input power levels. Hence, this study provides valuable insights for improving tunability in sensitivity and power for various actuation mechanisms. At atmospheric pressure and an input power of 19.5 mW, the device functions as a high-performance biaxial magnetic sensor with a sensitivity (S) of ~36.58% T^-1, an excellent linearity in the medium-to-high magnetic field range of ±400 mT, and a minimum detectable field, B_min of 0.83 µT Hz^-1. In contrast, it can be tuned as a magnetic-field-insensitive actuator (S = 3.28% T^-1) with a transversal displacement of ~4 µm, utilizing a negligible power of 43 mW. The diverse operation highlights its hybrid functionality as an actuator or high-performance sensor. These features, combined with the simplicity of fabrication and low cost, make the proposed microdevice highly promising for developing a three-axis magnetic sensor and actuator network system, as well as for various industrial applications.