A team of researchers is gaining new insight into the smart materials used in ultrasound technology, finding striking similarities with the behavior of water. They investigated a behavior of smart material called piezoelectricity, which is the interchange of mechanical energy with electrical energy. In piezoelectricity, applying an electric field to a material reorients dipoles within it; this is the key to the functionality of the material.

As the positive ions move off center, the cages of ions surrounding them either shrink or elongate in a concerted fashion, causing the material to change shape. In ultrasound devices, providing voltage makes the material change shape, or vibrate, and those vibrations enter the human body and echo around.

Recently, a set of materials was discovered that scientists believe gives higher piezoelectric performance than previous ones. As the material cools down, the dipoles clump into groups called polar nanoregions. As these regions grow larger, it becomes increasingly difficult for them to respond. The researchers showed that, while at higher temperatures the dipoles are in fact floating free as the temperature cools. The dipoles find each other and form the polar nanoregions. Domain walls between dipolar regions lead to enhanced piezoelectric properties in the material.