Laser-induced vibrations reveal blood cell damage caused by diseases

Science : The photoacoustic effect is the creation of sound waves in a material caused by the absorption of pulses of light. Because sound waves can be used to determine the shapes of objects, Michael Kolios of Ryerson University in Toronto and his colleagues decided to try using the effect on red blood cells. They created a laser that pulsed once every 760 ns, which induced sound waves with a frequency of more than 100 MHz. When they tested the laser on human blood samples, they were able to observe very small details in the shapes of the red blood cells and thus recognize changes due to diseases such as malaria or sickle cell anemia. The method requires much less blood than standard tests and is significantly faster. However, it is not useful for analyzing diseases that affect platelets or white blood cells, because they don’t absorb light as readily as red blood cells do.