Octopus-inspired sucker to absorb soft tissues: stiffness gradient and acetabular protuberance improve the adsorption effect

Rigid suckers commonly used in surgical procedures often cause absorption damage, while their soft counterparts are difficult to handle due to their weak anchoring. Alternatively, the octopus sucker is both soft and has strong suction power. Further observation revealed that its structure is self-sealing and that the tissues are layered in hardness. Inspired by said structure and the characteristics of associated materials, a bionic soft sucker with stiffness gradient and acetabular roof structure was proposed, made of silicone with varying hardness including structures such as acetabular roof and circle muscles. The automatic tensile force measurement system was used to experimentally analyze the adsorption performance of the suckers to the soft curved contact surface. Both dry and wet conditions were tested, along with practical tests on organisms. The bionic sucker adsorption force was increased by 25.1% and 34.6% on the cylindrical surface, and 45.2% and 7.3% on the spherical surface for dry and wet conditions, respectively. During the experiment, the bionic suckers did not cause notable suction damage to the contact surfaces. Thus, this type of bionic sucker shows good application prospects in the field of surgery.

Erection mechanism of glossal hairs during honeybee feeding

Many animals use their mouthparts or tongue to feed themselves rapidly and efficiently. Honeybees have evolved specialized tongues to collect nectar from flowers. Nectar-intake movements consist of rapid protraction and retraction of glossa from a tube formed by the maxillae and labial palps. We establish a physical model to reveal the driving mechanism of hair erection. Results indicate that the glossa of honeybees is similar to a compression spring. Experimental results show that hair erection is generated by the tension of hyaline rod and the elasticity of segmental sheath. The retractor muscle of hyaline rod is contracted at first, which compresses the sheath of pigmented rings and flattens the hairs. While the retractor muscle of hyaline rod relaxes, the elastic energy storage in the compressed glossal sheath will release to change the equivalent stiffness of glossal sheath and erect glossal hairs. These results explain the erection mechanism of glossal hairs during honeybee feeding.