We aim to develop a self-healing material for soft robots to address challenges such as frequent damage and high repair costs in underwater environments. Current self-healing materials are often slow and require specific environmental conditions to activate, limiting their use in harsh marine conditions. To overcome these limitations, we designed a self-healing system, incorporating both an adhesion module and a self-healing module. In addition, we have designed an adhesion module and a tyrosinase oxidation system to enable the self-healing module to adhere efficiently to the surface of the material.

Fig. 1 | Expected usage of the fusion protein TRn4-mfp5.

a. Schematic diagram of the TRn4-Mfp5 fusion protein structure; b. Expression and usage of TRn and TRn4-Mfp5 fusion proteins.

Our final product consists of two key components: the adhesion module and the self-healing module. Both components are first dissolved in Protein solvent. The adhesion layer is applied to the soft robot's surface, followed by the self-healing material. Once a film is formed, the robot can be deployed underwater. Laboratory tests have confirmed that our self-healing material meets the expected performance under controlled conditions.

Adhesion module:Includes TRn4-Mfp5 protein powder (a fusion of squid ring teeth protein and mussel foot protein), Protein solvent, a mixing container, and an application brush.

Self-healing module:Includes TRn protein powder (a highly repetitive sequence derived from squid ring teeth protein), Protein solvent, a mixing container, and an application brush.

Fig. 2 | TRn protein powder.

Adhesion module:Dissolve the appropriate ratio of TRn4-Mfp5 protein powder in Protein solvent. Mix thoroughly and apply evenly to the substrate material, allowing a film to form.

Self-healing module:Dissolve the TRn protein powder in Protein solvent. Apply it over the adhesion layer, let it form a film, and the material will be ready for underwater use.

Protein powders should be stored at -20°C to ensure their long-term stability and activity.

The self-healing material is not limited to soft robots, it can also be applied to other advanced devices, including robotic skin, flexible electronics and implantable medical devices, improving durability and reducing maintenance costs. We envision expanding our product into multiple lines to meet the diverse needs of various industries. The key requirements for our self-healing material include:

Fig. 3 | The application of self-healing material in the future.

1.High-performance healing: Our material forms extensive hydrogen bonds and π-π bonds, enabling rapid recovery of structure and function after damage, with excellent mechanical properties and durability.

2.Short healing time: Unlike traditional methods, our material significantly reduces the time required for recovery, ensuring the integrity of the material in a short timeframe.

3.Low healing conditions: Our material can heal at room temperature environments without the need for external energy input.

4. Eco-friendliness: While some self-healing materials can pollute the marine environment, ours can degrade in the natural environment, minimizing environmental impact.

Fig. 4 | Five key requirements.

We have already tested our material on various devices and aim to develop it into a versatile product line to cater to different applications. With continued research, our project has the potential to create a widely applicable, new-generation self-healing material.

Although our material has proven effective under laboratory conditions, its stability and performance in complex marine environments require further testing and optimization.

Due to the limiting conditions, we have not yet been able to test the material on a full-scale soft robot. We hope to collaborate with relevant institutions for further validation.

The performance of the self-healing material may vary depending on the base material of the soft robot. We are currently exploring these factors to fine-tune its application across different substrates.