The monitor, called ELFI-monitor, is based on dynamic light scattering. A low-power laser beams light into the skin, and the red blood cells in the underlying skin return the light which is recorded in a light sensor. The movement of the red blood cells is affected by the rhythmic cardiac contractility. in this manner, heart rate and rhythm can be assessed. The ELFI monitor also contains an embedded temperature probe and a miniature 3-D motion sensor, allowing capture of additional parameters.