Design and dynamics analysis of a compact tattooing mechanism for a capsule endoscope

Capsule endoscopes (CEs) have been highlighted as a next generation diagnostic device for the digestive organs (i.e. the stomach, small bowel and colon). Although CE imaging functions and control techniques have been continuously studied, CEs cannot completely replace conventional wire-based endoscopes because current commercial CEs only have diagnosis functions. To extend the range of applications for CEs, functional modules (e.g. biopsy, polyp removing and drug delivery modules) that can be installed in CEs have also attracted continuous attention. Therefore, in this paper, a simple and compact tattooing mechanism is proposed to carry out endoscopic tattooing, an important function of conventional endoscopes. The proposed tattooing mechanism is sufficiently compact to be applicable to conventional CEs. It ejects vertically and then withdraws the tattooing needle after the ink injection is completed. The insertion depth is kept within 3 mm to accommodate the properties of the stomach. Lastly, a dynamics analysis using a commercial code is carried out to determine a workable model considering the tattooing fluid effect.