The development of a multifunctional noncontact manipulation method is desired in cell manipulation. In this paper, we theoretically study and experimentally demonstrate the method of cell manipulation based on swirl. We analyze the swirl flow field features and the cell manipulation mechanism. The swirl is constructed by jetting fluid through three microtubules, and the cells are manipulated using the low pressure of stagnation point and the constant vorticity in the flow field. The experimental results indicate that the cell can be trapped robustly using the stagnation point of swirl. Moreover, the cell rotates with the same angular velocity at any position of the swirl flow field, and the cell is transported along with the movement of the stagnation point. Finally, we extend the application of swirl to manipulate multiple cells. Overall, this method can achieve trapping, rotating, transporting, pairing and enriching for cells, which realizes multifunctional cell manipulation.

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Automatic alignment of micro-component position and posture is an important part of micro-assembly. A self-calibration method of micro-components based on a droplet manipulator is proposed. The shape of the operating surface of the droplet manipulator is changed according to the shape of the micro-component and a droplet of the corresponding shape is formed; the position and posture of the operating surface of the droplet manipulator is used as a guide to drive the rapid alignment through the recovery force of the liquid bridge to achieve self-calibration of the micro-component. The self-calibration principle and process are analyzed using rectangular and triangular micro-components as examples, and the effectiveness of the proposed method is demonstrated experimentally. The research and experimental results show that the self-calibration can be achieved by changing the shape parameters of the operating surface of manipulator and controlling the corresponding droplet form; the self-calibration of position and posture of micro-components with different shapes and sizes can be achieved by matching the operating surface shape of the droplet manipulator and the micro-components; the automatic calibration success rate is 100% under the condition that the contact surface of the micro-component is completely wetted.

This paper proposes a microfluidic system for particle manipulation, which is comprised of a microfluidic chip, a driving device, a manipulation dish, and associated accessories. The microfluidic chip integrates a swirl structure with three microchannels, allowing for trapping, rotating, transporting, pairing, and enriching particles with different parameters by controlling the jet velocity of each microchannel. The driving device is mainly constructed with three push–pull syringe pumps to ensure the stability of the swirl flow field during manipulation. Experimental results demonstrate that the developed microfluidic system can achieve multifunctional and long-term (hours) particle manipulation.