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. 2020 May 7;8:327. doi: 10.3389/fcell.2020.00327

FIGURE 1.

FIGURE 1

The PANDA system. (A) Schematic of the PANDA principle. The internal air of the system is withdrawn from the air chamber, leading to the pressure of the air chamber (P) being less than the atmosphere pressure (Patm). The pressure difference allows the cell solution located on the well plate to enter into the air chamber. The cohesive force causes the cell solution to form a droplet while the adhesive force from the holding layer prevents the droplet from dripping that eventually forms the hanging drop. The PANDA system can be placed in the incubator and each hanging drop can allow the cells to spontaneously form the spheroid (or microtissue). The air can gradually penetrate through a gas permeable tubing to balance the internal pressure and the surrounding pressure. (B) The exploded view of the PANDA system. Scale bar represents 2 cm. (C) The schematic of the PANDA system connected to a syringe pump. (D) The hanging drops formed after using the PANDA system. Scale bar represents 1 mm.