# Lamprey-Inspired Amphibious Suction Disc with Hybrid Adhesion Mechanism

## TL;DR

This paper introduces a hybrid suction disc inspired by lampreys that can grip surfaces strongly in both air and water, enabling versatile robotic applications.

## Contribution

A novel hybrid adhesion mechanism combining shape-memory polymers and vacuum suction for amphibious, reversible attachment.

## Key findings

- The hybrid disc achieved peak pull-off forces of 562 N in air and 590 N underwater on smooth surfaces.
- The design improved adhesion by 377% in air and 270% underwater compared to vacuum alone.
- The disc enabled successful robotic demonstrations of cross-medium manipulation on a mechanical arm.

## Abstract

Bioinspired adhesives mimicking octopuses, tree frogs, and geckos enable robots to grip and manipulate diverse surfaces. However, most existing systems use a single adhesion mechanism, limiting adaptability and hindering strong, reversible attachment across diverse surface conditions and environmental media. Here, inspired by the oral sucker of the lamprey (Lethenteron reissneri), we present a hybrid suction disc that integrates a thermally switchable shape-memory polymer (SMP) panel for surface conformity and a soft silicone lip for vacuum suction. When heated, the SMP softens to conform to surface irregularities; subsequent cooling restiffens it, enabling mechanical interlocking with surface asperities under vacuum. This synergistic design achieves robust, reversible, and cross-medium adhesion on challenging surfaces, both in air and underwater. The disc generated peak pull-off forces of 562 N in air and 590 N underwater on smooth substrates, over 850 times its own weight, and maintained strong adhesion even on rough surfaces (>707 μm) where conventional suction fails. Incorporating the SMP improved adhesion by 377% in air and 270% underwater compared to vacuum alone. Shear friction tests showed similar enhancements, and attachments remained secure for 26.8 h under load. The hybrid disc also enabled robotic demonstrations of gripping and cross-medium manipulation when mounted on a mechanical arm, highlighting its potential for real-world robotic applications. This work paves the way for developing multimodal adhesion systems and amphibious robots capable of adaptive gripping and reliable operation across diverse environments.