A dynamic silicone-based material enables pressure sensors that reshape, heal damage, and disassemble, offering new capabilities for soft robotics and wearables.
(Nanowerk Spotlight) Machines that interact with people and their environment—whether in the form of wearable medical sensors, soft robotic grippers, or surgical instruments—require a surface that can stretch, bend, sense pressure, and respond to damage. These surfaces, often referred to as robotic skins, act as the outer layer of soft machines, enabling them to conform to complex shapes, detect touch or strain, and adapt to unpredictable use conditions. Unlike rigid electronics, robotic skins must be flexible, responsive, and in some cases disposable.
To meet these demands, engineers have developed a variety of synthetic materials with properties such as self-healing, tunable stiffness, or sensitivity to pressure. But integrating all these features into a single material system remains an unsolved challenge.
Most materials that can heal themselves rely on reversible chemical bonds, which allow broken structures to reconnect. However, these bonds typically leave the overall network structure of the material unchanged, limiting its ability to modify stiffness or shape. Other systems can be reconfigured mechanically or programmed to degrade, but often at the cost of complexity or limited compatibility with existing components. These trade-offs have hindered the development of robotic skins that are not only multifunctional but also practical for real-world applications such as wearable diagnostics, minimally invasive surgery, or field-deployable robotics.
One key limitation is that most soft materials cannot be reprogrammed after fabrication. Their internal structure is fixed, which means that once the material’s properties are set, they cannot be altered without replacing or rebuilding the component. Materials that can permanently adjust their structure, heal damage, and degrade safely would represent a substantial shift—enabling systems that are not just soft, but adaptable in a controlled and durable way.
Researchers at ETH Zurich have now developed a silicone-based material system that achieves this integration. By using a phosphazene catalyst to activate two types of bond exchanges in siloxane networks—a chemical backbone common in commercial silicones—they demonstrate a surface layer that can reshape itself, recover after damage, become mechanically stronger over time, and disassemble entirely under specific conditions. This advance offers a scalable, tunable material for applications requiring surfaces that are at once sensitive, robust, and responsive to their environment (Advanced Science, “A Shape‐Adaptive, Performance‐Programmable, Self‐Healable and On‐Demand Destructible Robotic Skin via Self‐Strengthening Dynamic Silicone”).
The material, called “OmniAdapt” by the research team, is built from commercially available silicone elastomers embedded with silica fillers. These fillers are commonly used to enhance mechanical strength and are already found in many soft robotic and medical devices. The innovation lies in activating dynamic behavior within this material using a strong base known as a phosphazene catalyst. When introduced into the silicone, the catalyst generates reactive species—silanolates—that initiate bond exchanges.
These exchanges occur in two ways. Inter-chain exchanges form new bonds between different polymer chains, allowing the material to heal and reshape. Intra-chain exchanges break bonds within a single polymer chain, producing small ring-shaped molecules that evaporate, permanently removing material and altering the internal structure.
This dual mechanism allows the material to do something unusual: not only heal and reshape, but also reconfigure its performance. As cyclic siloxanes evaporate, the silicone network becomes denser and stiffer. At the same time, the loss of polymer material exposes and concentrates the silica fillers, further increasing mechanical strength. The researchers found that by adjusting the catalyst concentration and applying heat, they could control this process with precision. At low catalyst levels and moderate temperatures, the material heals and becomes stronger. At higher catalyst concentrations and elevated temperatures, it breaks down entirely, effectively destroying itself.
Overview of on-demand programmable silicones toward Omni-Adaptive robotic skin. a) Omni-Adaptive robotic skin integrated with shape adaptability, sensitivity tuning, self-healing, and on-demand destruction, enabled by P4-tBu triggered silanoate exchange via inter-chain and intra-chain pathways. (click on image to enlarge)
To demonstrate practical use, the team fabricated pressure sensors using the dynamic silicone as a dielectric layer—the insulating material between electrodes. These sensors could be reshaped by heating and retained their new form once cooled. After thermal treatment, the sensors not only maintained function but showed a significant increase in pressure sensitivity. The initial sensor registered a sensitivity of 1.68 kilopascals per unit pressure. After treatment at 150°C, the sensitivity rose to 4.67 kilopascals. This increase was due to structural changes in the material: the dielectric layer shrank in thickness, and the internal microstructure became more compressible under pressure, amplifying the sensor’s response.
The sensors also showed faster response and recovery times after reconfiguration. Structural tightening from thermal treatment reduced internal damping, allowing signals to propagate more quickly. During testing, response time decreased from 0.78 seconds to 0.468 seconds, and recovery time improved from 0.936 seconds to 0.624 seconds. These changes enhance the material’s potential for real-time sensing in soft robotic and wearable systems.
An important challenge in soft materials is signal drift, often caused by viscoelastic behavior—the tendency of a material to deform slowly under stress. But in this system, the dynamic bond exchange reactions do not activate at room temperature, so the material remains elastically stable during normal operation. This reduces drift and ensures repeatable sensor behavior over time. The reconfigured sensors maintained performance through 10,000 loading cycles, confirming mechanical durability and signal stability.
The self-healing capability of the material extends beyond simple repair. After a mechanical cut, the silicone reformed its internal network during heating, closing the gap and restoring electrical performance. More notably, the healed material became stiffer and more sensitive than the original. This outcome differs from conventional self-healing materials, which typically aim to restore baseline properties. Here, the act of healing modifies the internal structure in a way that enhances function.
To test the system in a more complex configuration, the researchers molded a flat sensor into a 3D heart-shaped structure after healing. They embedded a grid of electrodes onto the reshaped skin and measured localized pressure responses. The sensor array accurately captured spatial pressure patterns on the curved surface, showing that the material can conform to anatomical shapes while maintaining high sensitivity. This suggests applications in surgical robotics where instruments need to wrap around tissue and provide tactile feedback.
The researchers also explored on-demand disassembly. By increasing the catalyst concentration to 5 percent and heating the material, they accelerated intra-chain bond breakage and loss of cyclic siloxanes. This process led to material fragmentation and a total mass loss of about 70 percent. The silicone essentially broke apart, enabling a form of controlled destruction. This could be useful for temporary sensors, disposable medical devices, or systems that must be deactivated after completing their task.
What distinguishes this material system is that all of these behaviors—healing, reshaping, strengthening, sensing enhancement, and degradation—emerge from a single underlying chemical mechanism. Unlike previous approaches that required different materials or design elements for each function, this strategy works within a unified framework based on commercially available silicone. That makes it more feasible for real-world adoption.
The ETH Zurich team has demonstrated that dynamic siloxane chemistry, when paired with controlled catalyst loading and thermal activation, can support a wide range of physical behaviors relevant to robotics and wearable electronics. By modifying how the material responds to damage, heat, and chemical inputs, they have created a robotic skin that does not just passively deform but actively reorganizes itself. This capacity for self-directed adaptation offers a path forward for more autonomous, resilient, and sustainable soft systems.
Get our Nanotechnology Spotlight updates to your inbox!
Thank you!
You have successfully joined our subscriber list.
Become a Spotlight guest author! Join our large and growing group of guest contributors. Have you just published a scientific paper or have other exciting developments to share with the nanotechnology community? Here is how to publish on nanowerk.com.
