Soft rubber balls are usually used as suction devices. There are two check valves. When the ball is squeezed, air is discharged from one exhaust valve, the ball is released, and gas is sucked into the ball from another valve, so that the air pressure in the cupping can be reduced and can be absorbed after repeated times. The so-called one-way valve is that there is a rubber sheet outside the outlet, which opens when the gas comes out and blocks the inlet when the gas wants to enter. Very simple and practical.

Other vacuum pumping methods are expensive, so it is enough to use a motor to drive the vacuum pump and the computer to control the operation of the motor. However, motors and pumps need a certain volume and weight, and vacuum pumps are more precise and have a higher failure rate. There is also a micro vacuum pump, the principle is close to a rubber ball, a small rubber ball and two one-way valves. The motor rotates to squeeze the ball, and the gas is exhausted.