Lasers can stimulate nerves and synchronize the pulsing of heart cells, but now they can control organs. In a breakthrough experiment, scientists used infrared light to control the beats of a quail's heart.
A team at Cleveland's Case Western Reserve University took a quail embryo out of its egg and attempted to artificially speed up its heartbeat using properly focused infrared light. They pumped pulses of the light along a short optical fiber until it was just half a millimeter away from the embryo's heart. They fired the laser every half second, and the heartbeat quickly sped up from 1.5 times per second to twice a second to match the laser pulse.
The team chose the 1.87-micrometer wavelength because water absorbs some of that particular band of infrared light, which avoids the nasty side-effect of all that focused light cooking the cells. In fact, that absorption is key to the laser's success - the relatively mild increase in temperature affects the parts of the cells that collectively control the heart rate and forces it into lockstep with the laser pulse. The team reported no laser-related damage to the heart at all, although the quail embryo ultimately died because they had to remove it from its egg in order to conduct the experiment.
Duco Jansen, who worked on the experiment, explained what's next for the laser pulse technology:
"This is an alternative to electrical stimulation with higher spatial resolution. And since we're stimulating in a domain different than the electrical domain in which we're recording data, it avoids interference."
Beyond enabling better research, this makes optical pacemakers a genuine possibility, which would avoid the interference issues that their current electrical counterparts often encounter. Researchers will need to gain a better understanding of just how the laser alters the heartbeat before such pacemakers can be built.
To get a better idea of how the laser pulse works, check out the video below of the experiment (no audio required):