Vibration Study of the Piezo-Driven Pipettes Immersed in Viscous Liquids

Intracytoplasmic Sperm Injection (ICSI) is regarded as one of the most useful assisted reproductive technology (ART). During ICSI, a single spermatozoon is mechanically injected into cytoplasm of an oocyte using a glass needle, called a micro-injection pipette. The micro-injection pipette is usually controlled by a micromanipulator for the precise movement. In the case of rodent ICSI the Piezo-driven pipette is needed. However, one undesirable aspect of the Piezo-driven pipette is that the technicians have to use mercury in the micro-injection pipette in order to achieve consistent results. It is commonly held that the large density of mercury strongly affects the pipette vibration. In this work, we analyze the effect of mercury on the vibration characteristics of the Piezo-driven pipette. The pipette is modeled as a cantilever beam immersed in a viscous liquid. The forces on the pipette by the surrounding liquid include both inertial force and viscous force. The steady state response of the pipette is obtained by the finite element method together with the numerical integration method. We investigate the pipette dynamic responses when different fluids are used as the plug inside the pipette and as the fluid surrounding the pipette. Based on the analysis, we conclude that the effect mercury has on the vibration is not the main reason that it facilitates the ICSI.