A large number of physiological signals generated by human activities, including strain and temperature, are an important data source for medical health and motion monitoring, and it is of great significance to use flexible wearable devices to realize the perception of strain and temperature. Flexible sensors are the core components of flexible wearable devices, and their development trend is integration and multi-function. It is still a difficult point to develop flexible strain-temperature dual-modal sensors to monitor and distinguish signals such as strain and temperature with high resolution.
In this study, the magnetic elastomer with the magnetoelastic effect in the strain-magnetic conversion unit of the dual-mode sensor provides a magnetic field that changes with strain, and through the built-in Co-based magnetic amorphous wire, it can sensitively detect the small change of the magnetic field, so as to output the changing impedance and realize the perception of strain. In addition, the work cleverly designs a dual-function Cu-CuNi thermocouple coil that not only realizes the output of impedance, but also has a Seebeck effect that enables temperature perception. Further, by adjusting the relative modulus of different regions of the strain-magnetic conversion unit, that is, the relative modulus of the magnetic elastic tube and the non-magnetic elastic tube, the magnetic field can be controlled at a speed that changes quickly, so that the strain sensitivity can be adjusted. The sensor achieves a low detection limit of 0.05% strain and 0.1 °C, high strain and temperature sensing sensitivity of 5.29 and 54.9 μV/°C. In addition, the coupling and mutual interference of the strain-temperature signal output of the dual-mode sensor are also verified from simulation and experiment. The temperature output signal and the strain output signal under different temperatures of the dual-mode sensor were tested separately, and it was found that the tubular heterostructure of the sensor could effectively avoid the interference of strain on temperature, and the magnetic energy of magnetic amorphous filaous filaments and magnetic particles had good temperature stability at lower than the Curie temperature, which could ensure that temperature strain sensing had almost no effect.
Source: Sensor Expert Network