Abstract: Venus fl ytrap 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 
diff erent 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 crosssection 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 stiff ness 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 
off er inspirations for the development of high-performance tactile sensors.

Key words: Venus fl ytrap, Morphological structure, Mechanical properties, Trigger hair, Bioinspiration