Free Vibrations and Frequency Sensitivity of Bionic Microcantilevers with Stress Concentration Effect

Inspired by the slit sensilla of spider legs, this study proposes a novel bio-inspired microcantilever sensing structure aimed at enhancing the natural frequency and sensitivity of the sensor. The bionic cantilever integrates the characteristics of a stress concentration region (SCR) and biomimetic slit-based structure. The presence of the SCR and slit-based structure endows the cantilever with a segmented configuration, enabling the establishment of a dynamic model based on the Euler–Bernoulli beam theory. By employing the Rayleigh–Ritz method to solve the Rayleigh quotient in segments, an analytical expression for the natural frequency of the bionic microcantilever system is derived. The validity of the theoretical results is verified through comparisons with classical cantilever models and finite element simulations. The effects of key parameters, including the position, length, and width of the SCR, as well as the position, width, and number of slits, on the system’s natural frequency are systematically analyzed, leading to an optimal design for significantly improving the natural frequency. The results demonstrate that the rational design of the SCR can markedly increase the system’s natural frequency, while the slit-based structure further enhances sensitivity by optimizing stress distribution. By adjusting the parameters of the SCR and slits, the sensor’s performance can be flexibly optimized. Compared to classical microcantilevers, the proposed bionic structure achieves more than 50% improvement in natural frequency, demonstrating significant advantages in detection performance and validating the effectiveness of the proposed structural optimization approach.