Integrated Acoustic-Vibratory Sensor Inspired by the Ear Bones of Sea Turtles for Heart Sound Detection

Biomimetics is an indispensable discipline in modern sensing technology and has been the source of inspiration for many significant inventions. Building upon the foundation of MEMS cantilever beam accelerometers, this paper combines biomimetic theory to propose an integrated MEMS acoustic-vibratory sensing structure that imitates the ear bones of sea turtles. Additionally, a novel acoustic packaging is designed based on the principle of the megaphone. Through simulation analysis, micro-nano fabrication techniques, and computer numerical control (CNC) machining, the fabrication and integration of the sensing structure are achieved. Subsequently, an acoustic testing platform is constructed for acoustic testing, and vibration testing is conducted using a vibration exciter. Experimental results demonstrate that the acoustic sensitivity of the MEMS biomimetic sensing structure can reach up to -21.926 V/Pa (re: 1 V/Pa) within the 20-200 Hz range, enabling the detection of periodic heart sound signals. Furthermore, compared to other accelerometers, the proposed biomimetic sensor exhibits significantly improved vibration sensitivity, reaching 5.3 V/g, aligning with the biomimetic mechanism of sea turtle's ear bones. The aforementioned research provides a new solution for low-cost heart sound detection and establishes a foundation for future biomimetic theories and composite sensor technologies.