Abstract
Artificial hearts which we now use are of air-driven sac type and driving device is fluid amplifiers with electro-pneumatic converter.
A blood handling part of artificial heart has a siliastic ventricle of 47 ml., which is in an acryl outer case of 95 m l. The outer case is connected to the driving device with a vinyl tube of 8 mm. in diameter and 2 m. in length.
A driving device consists of a cardiac synchronizer, an oscillator, an electro-pneumatic converter and two power fluid amplifiers.
The cardiac synchronizer produces synchronized electric pulses by an electro-pneumatic converter. The electro-pneumatic converter is bistable wall attatchment type and has an electro-magnetic relay at a control part of the fluid amplifier. It converts electric pulses into pneumatic signals of 0.1 kg/cm2.
The pneumatic pulses drive final fluid amplifiers which consist of two types of monostable fluid amplifier (left and right) and produce pneumatic driving pulses. The air pressure of the output pulses is about 0.3 kg/cm2 and its flow rate is about 30 l/min in the left side device and 0.05 kg/cm2, 30 l/min in the right side device.
Characteristics of this control device are (1) perfect synchronization with natural heart, (2) good fitting to Starling's law, (3) adequate shape of driving pulse wave and (4) long durability and high reliability.
A driving device for the artificial heart with a pure fluidic oscillator and a pulse shaping amplifier is also developed. This device gives pure pneumatic instrument.
The newest device is the pneumatically actuated valve. This may produce many new method of fluid control.
