**3.3 Innovative vitrification devices**

A new solution to increase the cooling rate reducing the use of cryoprotectants consists in the physical reduction of liquid nitrogen temperature, as happens in the **Vit-Master**, a new device developed at IMT, Israel. In order to avoid the vaporization of N2, the temperature of liquid nitrogen is reduced until - 210◦ (boiling point of nitrogen), applying a negative pressure (Arav et al., 2002). The evaporative cooling causes the nitrogen to partially solidify, thus creating a nitrogen slush. Samples immersed in nitrogen slush cool more rapidly because they come into contact with liquid nitrogen sooner than those immersed in normal liquid nitrogen (Cai et al., 2005). The *Vit Master* vitrification machine can provide a very high cooling rate (up to 135,000◦/min). The cooling rate is especially enhanced in the first stage of cooling (from 20 to -10◦), when it is six, four or two times higher with 0.25-ml straws, open pulled straws (OPS) or electron-microscope (EM) grids, respectively. Between -10 and -150◦, the cooling rate is only about doubled by use of the *Vit Master*, but that was found to be enough to reduce the chances of devitrification and recrystallization during warming.

Research about using a **Pulse Tube** for Vitrification is ongoing at "Sapienza" - University of Rome.
