A paper on the new printing method titled "Direct sound printing" has been published in the journal Nature Communications.
Researchers from Concordia University have created a new platform technology called direct sound printing (DSP), which uses soundwaves to create three-dimensional objects, compared to the current photo (light)- or thermo (heat)-activated methods. Focused ultrasonic waves allow users to produce complex geometries that are not otherwise capable.
"Ultrasonic frequencies are already being used in destructive procedures like laser ablation of tissues and tumors. We wanted to use them to create something.," said Muthukumaran Packirisamy, the paper's corresponding author.
The soundwaves are used to create sonochemical reactions, which generate small cavities, or bubbles, inside a liquid polymer solution, in this case, polydimethylsiloxane (PDMS). The bubbles only last picoseconds, but the temperature inside them reaches 15,000 Kelvin, and the pressure exceeds 1,000 bar, which is about 1,000 times the pressure of Earth's atmosphere at sea level. The minuscule duration of the reaction means the rest of the material is not affected.
"We found that if we use a certain type of ultrasound with a certain frequency and power, we can create very local, very focused chemically reactive regions. Basically, the bubbles can be used as reactors to drive chemical reactions to transform liquid resin into solids or semi-solids," Mohsen Habibi, the paper's lead author.
"We proved that we can print multiple materials, including polymers and ceramics. We are going to try polymer-metal composites next, and eventually we want to get to printing metal using this method," Packirisamy continued.
You can read more from the study here.