Forget Lasers. The Hot New Tool for Physicists Is Sound

Yushun Zeng works in a petri dish. Not with his fingers. A graduate student at the University of Southern California named Zeng has built a device that uses acoustic waves to trap and compress cells.

The purpose of the experiment is to find out if cancer cells are softer than healthy cells. Cancer cells can migrate and spread throughout the body according to previous experiments. Experiments that stiffen cancer cells could help researchers design therapies that make them harder to spread in the human body.

When you remember what a sound is, it makes sense to use sound to squeeze objects. Zeng uses acoustic frequencies too high to be heard by people. Zeng's device is called an acoustic tweezer. One example of how scientists are using sound as a tool is in the case of the tweezer, which uses sound as a pressure wave to destroy cancer cells.

The field of acoustics, or the science of sound, has been around for a long time. Building better acoustics for theaters and designing tuning forks were among the early technologies. Sound became an image tool in the 20th century. Military researchers developed a tool to find enemy subs, and medical engineers used it to image pregnant women. The use of sound to map spaces began when people were in the ocean.

Engineers are looking at sound in a different way than they used to. The sound is a wave. For example, your voice echoes in a canyon like light bounces off a mirror. Engineers have achieved unprecedented control over light over the last 50 years, with inventions such as lasers, fiber optics, and one-way mirrors. Engineers are trying to modify the tools for sound waves. According to Al, many groups have translated ideas from one field to another.

The acoustic tweezer is an example of a tool that was invented in the 1980's. The object feels a push from the light. Engineers shape the beam to make it feel like the laser is focused. Scientists have trapped and manipulated single atoms and molecules in optical tweezers and even used them to measure the springiness of DNA.

acoustic tweezers produce a train of sound waves by vibrating an object like a bell. There are pockets of pressure. Zeng uses sound waves to control where the pressure pockets are. Zeng can cause the surrounding fluid from a high-pressure zone to rush in by placing a low pressure zone over a group of cancer cells.