A twist-type rubber-tube pump

A twist-type rubber-tube pump, consisting of a tube with one side fixed and the other connected to a motor axis, has been developed. Liquid inside the tube is discharged according to the twist angle of the tube. Discharge volume ΔV of the pump is therefore approximated by the formula ΔV=[1-L0{L02+re2(θ-α)2}-1/2]S0L0, where S0 is the cross-sectional area of the tube, L0 is tube length, θ is twist angle, re is typical tube radius, and α is the delay angle of discharge. A prototype “twist pump” (tube inside diameter: 4mm; outside diameter: 8mm; length: 50mm) was evaluated by continuous pump tests. These tests showed that the prototype discharges 50µL of liquid at a maximum twist angle of 270° and has a long life; that is, the discharge pattern changes little after two million repetitions of the pump cycle.