Design of a broadband semi-conical PVDF ultrasonic sensor for obstacle detection applications

Most of the commercially available air ultrasonic transducers are ceramic based and operate at 40 kHz. This paper describes a method to design and build ultrasonic transducers using low-cost piezoelectric Polyvinylidene Fluoride (PVDF) film. The transducer has a semi-conical geometry, which provides a higher bandwidth, low ringing time compared to traditional ceramic ultrasonic transducers. We have built a prototype sensor and compared its typical characteristics with a commercially available ceramic transducer. In experiments, pulse compression technique used to detect reflected ultrasonic waves with a high SNR. We found it to be practical for applications requiring short-range obstacle detection and distance measurement.