A groundbreaking robotic gripper, inspired by the unique mouth structure of the lamprey, has been developed to effectively adhere to surfaces both in air and underwater. This innovative design addresses a common challenge in robotics: traditional suction cups often fail when applied to rough, porous, or wet surfaces.
According to Junzhi Yu, the lead researcher, "Current attachment methods encounter significant limitations in complex environments." He elaborated that conventional suction mechanisms struggle underwater due to fluid interference and can lose their grip on uneven surfaces. The goal was to create a versatile mechanism that could navigate both environmental conditions and varying surface textures.
The lamprey's oral structure serves as a model, combining a soft lip that forms a seal with stiff, tooth-like structures that latch onto tiny surface features. The research team has engineered a robotic version that mirrors this design. The device features a soft silicone lip encircling a core made from a shape-memory polymer (SMP), a material that transitions from soft to rigid based on temperature.
When heated slightly above 33° Celsius, the polymer softens, allowing it to penetrate microscopic pores on a surface. Once the temperature drops, the material hardens, maintaining its shape and securing its grip. Yu noted, "This hybrid approach decouples adhesion strength from the need for continuous vacuum, enabling the device to maintain a strong hold even if the vacuum system fails or air leaks occur."
Hybrid Grip
Many robotic grippers perform optimally under limited conditions, as standard suction requires a smooth seal. In contrast, the new design integrates suction with mechanical interlocking, ensuring a secure grip even when the vacuum seal weakens.
In laboratory evaluations, this compact 70-gram device demonstrated the ability to lift over 850 times its weight in both air and underwater. Its performance exceeded that of traditional suction cups, offering nearly three times the holding duration in air and up to 540% longer retention underwater.
Amphibious Applications
The device showcased remarkable versatility by handling various objects, from microelectronic chips to heavy tools like wrenches and hammers. Underwater, it successfully adhered to diverse items, including coins and shells, demonstrating reliability across different sizes and textures.
One notable demonstration involved a robotic arm using the gripper to manage a bionic manta ray robot, effectively transitioning between air and water. The researchers emphasized that this adaptability could enhance tasks such as marine maintenance, deep-sea exploration, and amphibious rescue operations.
While the system may be slower due to the heating and cooling cycles required for the SMP, its primary advantage lies in its dependable grip across challenging surfaces. This innovation, published in the journal Cyborg and Bionic Systems, holds promise for the future of robotics in dynamic environments.