Overcoming dead zones in ultrasonic sensors with acoustic metamaterial

Ultrasonic distance sensors can fail when an object is very close, creating a “dead zone” where detection is inaccurate. This study proposes using an acoustic metamaterial made from Helmholtz resonators to address that limitation. The approach is based on theoretical modeling that predicts reduced phase and group velocities, which should improve time resolution. The authors report experimental validation along with finite element method simulations. They find that as the ultrasonic frequency approaches the metamaterial’s resonant frequency, group velocity decreases, allowing more precise distance measurements even inside the dead zone. The work is positioned as a practical way to improve ultrasonic sensor accuracy for automotive sensing, robotics, and non-destructive testing.