Due to the wide variety of reactor forms in the field of biotechnology, conventional rod probes do not provide sufficiently representative measurement results. In this publication novel mobile spherical sensor units with a total diameter of 7.9 mm are presented. Based on simulations, these were optimized in their density for the best distribution in the aqueous medium. Furthermore, it was determined how different stirring speeds in typical bioreactors affect the distribution of the probes. The applicability of the probes is shown by means of three bioreactor types.