Smart materials or Active materials or Functional materials are designed materials that have diverse, dynamic features that enable them to adapt to the environment. They have one or more properties that can be significantly changed in a controlled fashion by external stimuli, the stimulus and response may be mechanical, electrical, …

A hydrophone is an underwater listening device, just as a microphone is used to detect sound in the air. Hydrophone detects sounds in the water and converts the acoustic energy into electrical energy by detecting changes in pressure in the surrounding environment. Hydrophones listen to sounds in the sea, but …