Venus flytrap can sense the very small insects that touch its tactile receptors, known as trigger hairs, and thus capture prey to maintain its nutrient demand. However, there are few studies on the trigger hair and its morphological structure and material properties are not fully understood. In this study, the trigger hair is systematically characterized with the help of different instruments.
Results show that trigger hair is a special cantilever beam structure and it has a large longitudinal diameter ratio. Besides, it is composed of a hair lever and a basal podium, and there is a notch near the hair base. The cross-section of the trigger hair is approximately a honeycomb structure, which is composed of many holes. Methods to measure mechanical properties of trigger hair are introduced in this paper.
Based on the mechanical tests, trigger hair proved to be a variable stiffness structure and shows a high sensitivity to the external force. These features can provide supports for the understanding of the high-sensitivity sensing mechanism of trigger hairs from the perspective of structure and material, and offer inspirations for the development of high-performance tactile sensors.