Abstract: Method of opening and closing a fluid passage comprises the steps of freezing fluid in the fluid passage by first cooling the fluid to a temperature below the freezing point of the fluid to close the fluid passage and after the fluid passage is closed, raising the temperature of the fluid close (or just below) to the freezing point of the fluid, whereby the fluid passage is maintained in a closed state with a small power supply and the responsiveness in opening the fluid passage is enhanced.

Abstract: An apparatus for transferring a small amount of fluid has at least one series of vibration pump units each having a fluid transfer pipe designed to perform a respirating action by the operation of a vibrator which vibrates in response to application of a high-frequency voltage. The fluid transfer pipes are connected in series via fluid diodes which serve to enable the fluid to flow only in one direction, while resisting reversing of the fluid, so that the fluid is transferred in one direction through the successive fluid transfer pipes. In order to minimize the pulsation of the fluid pressure at the downstream end of the apparatus, the vibrators of the pump unit are excited with predetermined phase differentials. Additional fluid diode is connected to the outlet end of the most downstream pump unit.