The Development of Piezo-Driven Tools for Cellular Piercing

Conventionally, intracytoplasmic sperm injection (ICSI) in the mouse is conducted with piezo-drills that use a droplet of mercury for damping. The use of mercury causes concerns of toxicity and contamination. Although Fluorinert can be used as a substitute for mercury to reduce piezo-drill’s lateral vibration, the damping effect is not as satisfactory as mercury. In this work, a modified piezo-drill without using mercury was developed for the cellular piercing of mouse oocytes. Experimentally, appropriate parameters of driving voltage and frequency were obtained for the penetration of the zona pellucida of mouse oocytes. Furthermore, the lateral vibration of the injection pipette is lower than 1 μm in deionized water, which is not observable at 400 magnificence. With the piezo-drill without using mercury, the system performs the cellular piercing of mouse oocytes with a maximum cleavage rate of 94.7% (n = 117).