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• Transducer fabricated by a thin PVDF film wound along its longitudinal axis in a logarithmic spiral shape. • Contiguous curved films that vibrate at specific frequencies, depending on the radius of the related portion of the spiral. • Wide band ultrasonic transducer in the range 30–95 kHz. • Omni–directionality on both the horizontal and vertical planes as ultrasonic receiver in the range between 30–95 kHz. This article proposes an ultrasonic sensor inspired by the shape of a bat's cochlea, which is part of one of the most sophisticated echolocation systems to be found among mammals. In this case, polyvinylidene fluoride (PVDF) was used for the fabrication of the sensor, which is manufactured by folding a sheet of the piezopolymer according to a logarithmic spiral geometry. It is characterized by a very broad frequency band, in agreement with numerical simulations and impedance analyses, and has a uniform radiation pattern both on the horizontal and vertical planes. The sensitivity of the sensor was evaluated in the range between 30–95 kHz, a well–suited frequency band for most bio–systems. [ABSTRACT FROM AUTHOR]