# Bio-Inspired Mechano-Sensor Based on the Deformation of Slit Wake
## 1 Introduction  
Mechano-sensors are a kind of sensor that can convert a variety of mechanical signals (such as air/water flow, vibration, touch, acoustic signal, and so on) into electrical signals [1; 2; 3; 4]. In the engineering field, mechano-sensors are important for engineering equipment to detect mechanical signals in the internal and external environment, because mechanical signals contain a lot of information for rehabilitation monitoring of advanced equipment, guiding the control of mechanical actuators, and precise motion control of intelligent robots in complex working conditions [5; 6; 7; 8]. Recently, there has been an urgent need to further significantly improve the sensing performance of mechano-sensors. However, after decades of research, the mechano-sensors based on traditional design methods are quickly approaching their performance limits. Therefore, exploring novel strategies is very important for developing mechano-sensors with excellent performance such as ultra-high sensitivity, low power consumption, durability, and so on. The signal-conduction sensory structure and signal-transduction materials are two major sensing elements of mechano-sensors [9; 10; 11]. The coupling design of the above two elements is key to achieving the optimal performance of various mechano-sensors. Because the mechanical signals cannot be directly received by signal-transduction materials, it first requires a highly specialized sensory structure to achieve the efficient collection of dispersed signals at the sites of nanoscale functional materials [12; 13; 14]. Obviously, it is one of the necessary ways for developing next-generation mechano-sensors by designing ahighly specialized sensory structure, which can achieve optimal signal transmission, for a corresponding mechanical signal. According to the classification of an exteroceptive and proprioceptive system, various types of mechano-sensors are divided into external mechano-sensors and internal mechano-sensors [15; 16]. Specifically, the external mechano-sensors extending or protruding from the surface of the equipment mainly utilize exteroceptive capabilities through the direct detection of external stimuli containing air/fluid-flow signals and tactile signals [17; 18]. For external mechano-sensors, various types of cantilever beams are widely utilized as the sensory structure because of its unique advantages in external mechanical-signal collection [19]. The internal mechano-sensors, as the important part of the proprioceptive system, are widely used to enhance the capability of the intelligent equipment to perceptive the changes in their own state via detecting the internal mechanical stimulus that is generated in the object body [20]. Internal mechano-sensors with excellent comprehensive performance have attracted extensive attention because of their significant role in improving the proprioceptive capabilities of intelligent equipment [8; 21]. However, contrary to the wide application of the cantilever beam as the sensory structure of external mechano-sensors, there is still a lack of an effective and widely used sensory structure for significantly improving the sensing performance of internal mechano-sensors. Obviously, it is an urgent problem to find a specific sensory structure that can be widely used and can significantly improve the performance of the internal mechano-sensor. In nature, arachnids (such as the spider and scorpion), in which visual systems have been highly degraded, have evolved a variety of mechano-sensilla to meet their survival needs in a harsh natural environment [12; 22]. Among various mechano-sensilla, the slit-based mechano-sensilla, as an important part of the proprioceptive system, are ingeniously used to sense the internal mechanical stimulation caused by walking and the external vibration signal [23; 24]. The slit-based mechano-sensilla are distributed at the front of the basitarsus joint.