Testing for ovarian cancer or a chemical presence may become much simpler thanks to a new microscopic acoustic device that has been dramatically improved by scientists at the U.S. Department of Energy’s Argonne National Laboratory, Argonne, IL. The device, known as a surface acoustic wave (SAW) sensor, detects frequency changes in waves that propagate through its crystalline structure, which makes it ideal for detecting the presence of chemicals or biomarkers present in a liquid or gas.

The initial wave is created by a piezoelectric effect, in which an initial electric signal is converted into a mechanical displacement. This displacement takes the form of a wave transmitted through the crystal.

In the SAW sensor, the signal travels like a seismic wave from the input transducer through the material to an output transducer, where it is converted back into an electrical signal. The wave's frequency is determined by the velocity of sound through the material, and the researchers are able to detect frequency, or pitch, changes in the waves as they propagate. The pitch changes are caused by changes in the density of the crystalline medium, which result from bonding of chemicals to receptors on the crystal or of proteins to antigens.

Argonne scientists added a new feature to the SAW devices, which significantly reduces their power consumption while simultaneously improving their sensitivity. They incorporated zinc oxide-filled microcavities designed to trap energy near the surface that otherwise would be lost to bulk waves, which reduced energy losses by 50 percent. They say that this may lead to the development hand-held biosensors.