## Summary of News: Self-Healing, Color-Changing Gel for Wearables and Soft Robotics **News Title/Type:** New Gel That Stretches 4600%, Heals Itself Can Be Used in Robotics **Report Provider/Author:** Interesting Engineering, authored by Christopher McFadden **Date/Time Period Covered:** Updated: September 14, 2025, 06:51 AM EST (Published: September 14, 2025) --- ### Main Findings and Conclusions Researchers in Taiwan have developed a novel **stretchable, self-healing gel** that exhibits a **color change under stress (pulling or heating)**. This breakthrough material combines **strength, self-healing capabilities, and built-in sensing** into a single, smart, rubbery substance. This is a significant advancement as most existing soft or stretchable materials either compromise on strength, healing, or sensing. The core innovation lies in the gel's molecular design, which utilizes **mechanically interlocked molecules called rotaxanes**. These ring-shaped molecules slide along a "rod" and are linked in daisy chains, allowing for expansion and contraction akin to a spring. A special fluorescent unit, **DPAC**, is attached to these molecules. DPAC glows orange when free to move but shifts to blue when its movement is restricted due to stretching or bending. This molecular mechanism directly couples with the gel's stretching, enabling a visible color shift from orange to blue under UV light when the gel is pulled. The gel is further reinforced with **cellulose nanocrystals**, which contribute to its self-healing properties by forming reversible hydrogen bonds. This allows the gel to **heal damage at room temperature within hours**, or even faster with mild heating. ### Key Statistics and Metrics * **Strain Capacity:** The material can safely handle approximately **4600% strain**. This means a 1 cm piece of gel can be stretched to 46 cm without breaking. * **Toughness:** The gel exhibits a toughness of **142 MJ/m³**, which is approximately **2.6 times tougher** than the same gel without the rotaxane molecules. * **Self-Healing Time:** Damage can heal at **room temperature in hours**, or faster with mild heating. ### Important Recommendations and Potential Applications The researchers highlight several promising applications for this new material: * **Wearable Devices:** Real-time monitoring of stress and strain in wearable technology. * **Soft Robotics:** Enabling parts in soft robots to be both strong and responsive. * **Artificial Skin and Biomedical Implants:** Creating artificial skin or implants that can sense and self-repair. * **Damage-Tolerant Electronics:** Developing electronics that provide visible signs of strain rather than failing suddenly. ### Significant Trends or Changes This development signifies a trend towards creating **"smart" materials** that integrate multiple functionalities (strength, healing, sensing) into a single composite. The ability of a material to visually indicate its own stress levels is a notable advancement in material science. ### Notable Risks or Concerns The news article does not explicitly mention any risks or concerns associated with the material itself. However, as with any new technology, further research and testing would be necessary to assess long-term stability, biocompatibility (for biomedical applications), and scalability for mass production. ### Material Financial Data No financial data or cost-related information is provided in this news report. --- **Source:** Interesting Engineering **Author:** Christopher McFadden **Published:** September 14, 2025
New gel that stretches 4600%, heals itself can be used in robotics
Read original at Interesting Engineering →The self-healing gel changes color under stress could reshape wearables and soft robotics. Updated: Sep 14, 2025 06:51 AM EST Researchers in Taiwan have developed a stretchable, self-healing gel that changes color when pulled or heated. It combines strength and built-in sensors in a single material that could have interesting applications in wearable devices and soft robotics.
In short, the new material can be thought of as a smart, rubbery material that tells you when it’s stressed out by literally changing color. This breakthrough is important because most soft or stretchable materials either stretch well but break easily, or stay tough but don’t heal themselves or sense stress.
This new gel, however, manages to combine strength, healing, and sensing capabilities in one material, which is a rare feat. The secret sauce behind the breakthrough is a clever manipulation of its molecular design. The researchers used mechanically interlocked molecules called rotaxanes, which are ring-shaped molecules that slide along a “rod.
” These are linked together in daisy chains with two rotaxanes linked together, which can expand/contract more like a spring. Self-healing, strong, and dual-sensing Using these, the team also attached a special fluorescent unit called DPAC to these molecules. When free to move, DPAC glows orange, but when restricted (like when stretched or bent), DPAC glows blue.
So, when you pull the gel, the rings slide and restrict DPAC’s movement, making the gel visibly shift from orange to blue under UV light. The interlocked molecules were chemically bonded into a polyurethane gel reinforced with cellulose nanocrystals (tiny, strong fibers). The cellulose helps the gel self-heal by forming reversible hydrogen bonds across the network.
Because the sliding molecules are built into the gel (not just mixed in), their motion directly couples with the gel’s stretching. When tested, the team found that the new material is extremely stretchy, able to safely handle ~4600% strain (like stretching 1 cm of gel to 46 cm without breaking). It is also extremely tough, exhibiting a toughness of 142 MJ/m³, which is approximately 2.
6 times tougher than the same gel without these molecules. Since the material also changes color under strain (shifts from orange to blue), you can map the stress distribution of the gel simply by observing the coloration. It also benefits from dual sensing as it also changes color with heat (orange at higher temps, blue when cool/strained).
But one of the main benefits of the material is its self-healing properties. This means it can damage heals at room temperature in hours, or faster with mild heating.RECOMMENDED ARTICLES Interesting potential applications This kind of material could prove very useful for wearable devices that monitor stress and strain in real-time.
The gel could also have some interesting applications in soft robotics, where parts need to be both strong and responsive. It could also, theoretically, be used to make artificial skin or biomedical implants that can sense and self-repair. The gel could also open the door for damage-tolerant electronics that don’t fail suddenly but show visible signs of strain.
In short, this is a smart gel where tiny sliding molecules act like both shock absorbers and stress indicators. Stretch it, and it heals itself while lighting up with a color change that tells you how much it’s being strained or heated. The study is available in the journal Advanced Functional Materials.
ABOUT THE AUTHORChristopher McFadden Christopher graduated from Cardiff University in 2004 with a Masters Degree in Geology. Since then, he has worked exclusively within the Built Environment, Occupational Health and Safety and Environmental Consultancy industries. He is a qualified and accredited Energy Consultant, Green Deal Assessor and Practitioner member of IEMA.
Chris’s main interests range from Science and Engineering, Military and Ancient History to Politics and Philosophy.RELATED ARTICLESJOBS
