Experimental study of a membrane compliance cavity to improve vitro simulation of the human circulation system under acceleration environment

Objective To improve the vitro simulation of the human circulation system under acceleration environment by studying a membrane compliance cavity. Methods The vitro simulation of the human circulation system equipped with a membrane cavity wherein the air and liquid was separated by a silicone membrane (0.2 mm or 0.4 mm thick) in order to prevent the gas got into the system as soon as the simulated acceleration caused air-liquid interface tilt. The segmentation of air-liquid interface and deformation of silicone membranes were recorded by a high definition camera when 20 to 200 mmHg pressure applied to the cavity to simulate the acceleration effect. The compliance values at different pressures were calculated. Results ①No air was found in the closed liquid loop when cavity was pressured. The deformation of 0.2 mm membrane was larger than that of 0.4 mm membrane. ②The membrane compliance cavity showed viscoelasticity feature both in pressure loading and unloading processes. When the cyclic loading was up to 3 times the loading curve of 0.2 mm membrane compliance cavity was almost overlapped on its unloading curve, but they did not coincide for the 0.4 mm membrane. ③The simulation range of 0.2 mm silicone membrane was in 0-1.4 ml/mmHg under 20-200 mmHg test pressures, while 0-0.4 ml/mmHg for 0.4 mm silicone membrane. Conclusions The membrane compliance cavity has solved the problem of the air-liquid interface segmentation under the simulated acceleration environment. The simulation range of compliance meets the needs of the vitro simulation for human circulatory system. Key words: Acceleration physiology; Blood circulatory; Compliance; In vitro simulation; Silica membrane cavity; Pilots