New `acoustic diode` may provide better ultrasound images in future

Washington – A new technology called an “acoustic diode,” which has been envisioned by researchers in China’s Nanjing University, could dramatically improve future ultrasound images by changing the way sound waves are transmitted.

Scientists described the theoretical framework for an acoustic diode – a device that achieves a one-way transmission of sound waves much the same as an electrical diode controls the one-way transmission of electrical impulses.

Researcher Jian-chun Cheng said that the one-way flow of sound would provide brighter and clearer ultrasound images by eliminating acoustic disturbances caused by sound waves going in two directions at the same time and interfering with each other.

Cheng asserted that the propagation direction of the output wave would be controlled freely and precisely and that these features are crucial for the medical ultrasound applications of the resulting devices.

The team developed its theoretical model based on a material not found in nature called a near-Zero Index Metamaterial (ZIM) and a prism to create high transmission efficacy acoustic waves that strike a reflective boundary from two opposite sides.

In theory, explained Dr. Cheng, this would produce a unique tunneling effect and an unprecedented property that the output waveform is kept consistent with those of the waves traveling toward a boundary.

The study has been published in the journal Applied Physics Letters.