Implemented edge shape of an electrical stimulus capsule.

Background: Recently, a capsule endoscope has been developed and many researchers have been trying to develop locomotive capsules. To develop locomotive capsules, the inner volume of the capsule has to be large enough to insert actuators, and the edge shape of the exterior capsule has to be suitable for locomotion. There are many locomotional methods, but an electrical stimulus method provides the appropriate power consumption, plus the shape of the capsule is the same as general telemetry capsules. In this paper, the optimal shape of the electrical stimulus capsule (ESC) was designed and implemented to provide the appropriate inner volume and moving speed of the capsule.

Methods: A simple mathematical model was used to simulate various capsule shapes, and simple mathematical formulae were used to simulate the relationship between the shape of the edge of the capsule and the contraction force of the small intestine. The optimal edge shape of the capsule was decided based on the crossing point of the volume and moving speed. To verify the simulation, two capsules were implemented as the control and experimental groups.

Results: From the in vitro experiments, four fresh intestines were used to measure the moving speed of the capsules. The average speed of the proposed capsule was 0.125 +/- 0.096 cm/s (20 V, 10 ms, 20 Hz), while the control group capsule was only 0.016 +/- 0.33 cm/s (20 V, 10 ms, 20 Hz), and both groups showed a significant difference from the statistical analysis (p < 0.001, Mann-Whitney rank sum test).

Conclusions: This paper presents a proposed design for the external shape of the ESC that could fill the need of researchers who want more inner volume and doctors who want to prevent the capsule from being stuck in the intestine.