Research on the Parameter Configuration Law of Transfer of Ultramicro Liquid by Pipetting Needle Based on the Quasi-static State.

Microscale device surface encapsulation needs to use ultrafine liquid transfer technology. This technology can transfer a liquid from a donor surface to a receptor surface in a controlled manner. However, the requirement of microscale encapsulation for liquid transfer amounts is generally at the pL level. Controlling liquid transfer volume, ensuring consistency, and ensuring droplet position accuracy became more difficult at this level. In light of the existing pipetting needle transfer ultramicro liquid transfer technology and considering a slow stretching liquid bridge can maintain a constant liquid transfer ratio, we conducted in-depth research on the parameter configuration law of liquid transfer at the pL level. This study reveals the parameter configuration law under the condition of constant transfer ratio through the Young-Laplace equation and the Navier-Stokes equation. Research has shown that the initial distance and capillary number () affect the transfer ratio at a slow stretching speed. Through ultramicro liquid transfer experiments, with stretching speeds between 0.01 and 0.5 mm/s, the transfer ratio remained constant, the accuracy of the rheology-Cross model in predicting liquid transfer ratios was verified, and the absolute deviation rate between the actual and the predictive transfer ratio is 6.26%. This research plays a crucial role in enhancing the precision and success rate of microscale liquid transfer.