Design of triggering mechanism for capsule endoscope

The capsule endoscope (CE) has been highlighted as non-invasive and discomfort-free endoscopic exploration of the small-bowel. Although current function of the CE is limited as inspection and diagnosis, further application such as drug delivery will be applied in the CE in near future. To exploit the CE for multipurpose, a proper mechanism reflecting limited volume of the CE is required. In this paper, we propose a novel triggering mechanism to activate functional tools in short time, which can be applied in drug delivery, tattooing procedure and biopsy. The proposed triggering mechanism consists of a nut fabricated by low-melting metal, a heating wire and a conical spring. To verify feasibility of the mechanism, acting force on the nut is measured and proper conical spring is selected. Then, triggering time is estimated based on numerical simulation and theoretical analysis. Lastly, activation test is implemented and triggering time is investigated. Conclusively, using the nut of 1.5 mm-height, the triggering mechanism is normally activated within 3.42 s (error rate =7.55%) with low input power of 12.5 W.