Robotic weighing for spherical cells based on falling speed detection

Cell weighing has great potential applications in probing the cellular composition and quantifying material interaction of the cell. In this paper, a novel and simple robotic weighing approach for spherical cells is proposed to avoid high cost of involved devices in traditional methods. According physical knowledge, the spherical cells released in enormous liquid environment tends to fall at a constant speed. The density of cell can be estimated from this constant speed, and in consequence, the mass of cell can be derived. Based on this point, the constant falling speed detection process is realized robotically on a traditional micro-operation system in this paper. Experimental results demonstrate that the detected density of sheep oocyte is accordance with the known water-percentage of biological cells, which proves the feasibility of the proposed weighing method. Furthermore, the proposed approach is proved to detect the tiny mass-variation of the cell (less than 2%), which proves the high sensitivity of our method.