Feeling paramagnetic micro-particles trapped inside gas bubbles: A tele-manipulation study

Surface tension forces, pressure forces, and drag forces arise once a micro-particle comes into contact with a gas bubble or a biological cell in diverse physical and biomedical applications such as targeted therapy, sorting, and characterization of cancer cells. We experimentally demonstrate that these forces can be estimated, scaled-up to the sensory range of a human operator, and sensed during a transparent bilateral tele-manipulation using an electromagnetic system and a haptic device. We find good agreement between the estimated interaction forces and the measured forces using a calibrated microforce sensing probe. The maximum interaction force between a trapped paramagnetic micro-particle and an oxygen bubble is estimated to be 4 μN. The estimated interaction force is scaled-up and used in the design of a tele-manipulation system (haptic device and an electromagnetic system) that enables motion control of the bubble in a two-dimensional space, while sensing the interaction forces with the bubble. We demonstrate experimentally that the operator senses maximum interaction force (surface tension, pressure, and drag forces) with the same order of magnitude as the calculated theoretical forces. The estimation of interaction forces at this scale provides broad possibilities in targeted therapy and characterization of cancer cells.