Scientists from the research center caesar in Bonn, associated with the Max Planck Society, and the Helmholtz research center Jülich published these findings in a recent article in Nature Communications.
It is a matter of scientific debate how microswimmers navigate. This fundamental question concerns scientists seeking to understand biological microswimmers, such as sperm, or engineers striving to design synthetic micro-robots.
The sperm tail serves multiple purposes: it is used as a propeller that drives sperm forward, as an antenna that captures and processes sensory stimuli, and as a “rudder” that sets the course accordingly. Sperm swim forward by waving their tail. As the wave travels from the head down to the tip of the tail, liquid is pushed backwards and sperm are propelled forward. For steering, the tail beats asymmetrically to one side, acting like the rudder of a boat; consequently, sperm move on a curved path.
The new study shows that sperm use a surprising mechanism to produce an asymmetric beat. Two different waves travel along the tail: one with a fundamental frequency and another with twice this frequency. To put it in musical terms, sperm play notes of different octaves. The superposition of these two waves results in a wave with...