Fig. 1

Photographs and specification of a disc with microcones (A) and locations of microcone application (B). In panel (A), photographs of microcones taken by scanning electron microscopy (left top) and stereoscopic microscopy (right top) are presented, and a specification of microcones is shown in the enlarged view. Approximately 180 microcones are arrayed on a circular disc of 7 mm in diameter. The microcones were regularly arrayed on a disc with a pitch of 0.4 mm. Each microcone has a flat tip with a diameter of 0.037 mm and a height of 0.3 mm. The disc was fixed on the skin with adhesive tape. In panel (B), filled circles indicate the approximate locations of microcone application (up to eight locations on the left and right). The locations were slightly adjusted depending on participants’ perceived symptoms and palpations performed by a physician