Techniques and structures are provided for manufacturing a flexible PMUT array. In one embodiment, a piezoelectric micromechanical ultrasonic transducer (PMUTs) array comprises a plurality of PMUTs, where each PMUT in the flexible array of PMUTs includes: a first polymer layer configured to support the PMUT, a mechanical layer configured to provide planarization to the PMUT, a first electrode, a second electrode, a piezoelectric layer configured to separate the first electrode and the second electrode, patterns on the first electrode, the piezoelectric material, and the second electrode configured to route electrical signals, and a cavity configured to adjust a frequency response of the PMUT.