Mechanosensors, as the core component of a proprioceptive system, can detect many types of mechanical signals in their surroundings, such as force signals, displacement signals, and vibration signals. It is understandable that the development of an all-new mechanosensory structure that can be widely used is highly desirable. This is because it can markedly improve the detection performance of mechanosensors. Coincidentally, in nature, optimized microscale trigger hairs of Venus flytrap are ingeniously used as a mechanosensory structure. These trigger hairs are utilized for tactile mechanosensilla to efficiently detect external mechanical stimuli. Biological trigger hair-based mechanosensilla offer an all-new bio-inspired strategy. This strategy utilizes the notch structure and variable stiffness to enhance the perceptual performance of mechanosensors. In this study, the structure–performance–application coupling relationship of trigger hair-based mechanosensors is explored through experiment and analysis. An artificial trigger hair-based mechanosensor is developed by mimicking the deformation properties of the Venus flytrap trigger hair. This bio-inspired mechanosensor shows excellent performance in terms of mechanical stability, response time, and sensitivity to mechanical signals.

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.

The hybrid manufacturing method of laser cladding deposition (LCD) additive manufacturing and electrochemical machining (ECM) is a promising approach to advanced manufacturing technology for difficult machined materials. The anisotropic electrochemical performance of LCD-produced Ti6Al4V alloy was studied in 15 wt.% NaCl solution by polarization curve measurements and ECM tests. The horizontal-plane (X0Y plane) exhibits a more stable passive film in both static electrolyte and low current density ECM processes than the vertical-plane (X0Z plane). Additionally, the horizontal-plane exhibits a higher material removal rate and more consistent dissolved surface roughness in comparison with the vertical-plane during the high current density ECM process. The microstructure of the LCD-produced Ti6Al4V alloy on the horizontal-plane consisted of equiaxed-like prior-β grains and slightly finer α-laths but was composed by columnar prior-β grains and coarser α-laths on the vertical-plane. These differences in the microstructural characteristics produce the distinctions observed in the electrochemical dissolution behavior and electrochemical machinability on the horizontal- and vertical-planes.

In engineering, cracks are typically regarded as defects due to enormous stress amplification at tip of the crack. Conversely, scorpion ingeniously utilizes the “risky” near-tip stress field of a crack-shaped slit to accurately detect weak vibration signal without causing catastrophic crack propagation from the slit tip. The present paper focuses on the balance strategy between structural safety and sensing accuracy of slit-based mechanical sensilla. We performed a detailed structural and mechanical property study of tissue around the slit wake utilizing a complementary combination of various experimental methods. The results indicate that there is a special thin surface membrane covering the slit wake and the elastic moduli of the membrane and exoskeleton are 0.562 GPa and 5.829 GPa, respectively. In addition, the ratio of bending stiffness between exoskeleton and membrane tissue is about 8 × 10⁴. The theoretical and simulation analysis show that the surface membrane—with appropriate elastic modulus and bending stiffness—can achieve different forms of deformation with the change of slit width for protecting the mechanosensory structure without sacrificing the sensing accuracy. This finding offers a crucial theoretical basis for the further design of bionic mechanical sensors based on the near-tip stress field of artificial cracks.

Internal mechano-sensors, as an indispensable part of the proprioceptive system of intelligent equipment, have attracted enormous research interest because of their extremely crucial role in monitoring machining processes, real-time diagnosis of equipment faults, adaptive motor control and so on. The mechano-sensory structure with signal-transduction function is an important factor in determining the sensing performance of a mechano-sensor. However, contrary to the wide application of the cantilever beam as the sensory structure of external mechano-sensors in order to guarantee their exteroceptive ability, there is still a lack of an effective and widely used sensory structure to significantly improve the sensing performance of internal mechano-sensors. Here, inspired by the scorpion using the specialized slit as the sensory structure of internal mechano-sensilla, the slit is ingeniously used in the design of the engineered internal mechano-sensor. In order to improve the deformability of the slit wake, the hollowed-out design around the slit tail of biological mechano-sensilla is researched. Meanwhile, to mimic the easily deformed flexible cuticular membrane covering the slit, the ultrathin, flexible, crack-based strain sensor is used as the sensing element to cover the controllable slit wake. Based on the coupling deformation of the slit wake, as well as the flexible strain sensor, the slit-based mechano-sensor shows excellent sensing performance to various mechanical signals such as displacement and vibration signals.