Precise Aspiration and Positioning Control Based on Dynamic Model Inside and Outside the Micropipette

Abstract

Cell aspiration is a common technique in cell manipulation for cell transfer or intracellular property measurement. In this paper, we present a robotic micromanipulation system for cell aspiration and positioning by a micropipette. Considering the relative motion of the object and the fluid, we first establish an overall dynamic model of microbead motion inside and outside the micropipette based on computational fluid dynamics (CFD). Then we design an adaptive sliding mode controller (ASMC) for microbead aspiration outside the micropipette and positioning inside the pipette based on the dynamic model. The controller is proven to achieve asymptotic stability by Lyapunov techniques. Simulation and experimental results demonstrate the effectiveness of the fluid model and the performance of the designed control system. Note to Practitioners—Cell aspiration with a micropipette is a key technology in cell manipulation. Generally, there is relative motion between the aspirated object and the fluid, resulting in large overshoot even aspiration failure. In this paper, we set up an overall dynamic model of microbead motion inside and outside the micropipette, combining microbead motion dynamics, fluid dynamics and pneumatic pump modeling. Based on this model, we design an ASMC for microbead aspiration outside the micropipette and positioning inside the pipette. In simulations and experiments, the positioning errors of the microbead of different sizes converge to zero without overshoot, revealing the strong robustness of the controller. Applications for this technology include cell or sperm aspiration and injection.