Abstract
Micro robotic colonoscope is a non-invasive intelligent examination instrument in recent years. Stable supporting is essential to the slide inner wall of gastro intestine. Double balloons method can be fixed on the colon wall efficiently and safely. This research aims at development of a novel miniature injection pump used to transfer air between the two balloons. The pump is composed of a linear actuator, an active valve, and a bellow. The linear actuator uses a DC motor, a gear reducer and a screw pair. The active valve shut off the inlet or outlet by squeezing the air tube. Two Shape Memory Alloy helixes actuate the valve's compression bar independently. The mechanism is designed in 3D software and a prototype is fabricated and assembled. it has 15 mm diameter, and 50 mm length, and 8.5 g weight. Some experiments are performed to measure the parameters. The endurable pressure ranges from 12 atms to 19 atms. The operating process indicates that the pump can work reliably. A model of the shut-off force is built to identify the characteristics of the pump. The results are consistent with the theoretical analysis. This pump uses a squeezing-shut-off mechanism, which is simple and reliable without air-tight.
