Where the Robot Meets the Human – The Materials Science of Skin, Touch, and Protection
What does it take to trust a robot's touch?
Not the abstract trust that comes from reading a safety specification or understanding a risk assessment. The immediate, instinctive trust – or the lack of it – that a person registers in the moment before a robotic hand makes contact with their own. The texture of the surface. The firmness of the grip: secure enough to hold, yet gentle enough not to harm. The sense that what is touching you is designed with some understanding of what human skin expects.
This is the frontier that humanoid robotics is approaching. Once these machines graduate from tightly controlled manufacturing environments into hospitals, care facilities, homes, and public spaces, the physical interface between robot and human becomes a design problem that no amount of software can fully solve. It requires the right material – one that can be soft when softness is needed, durable when durability is demanded, and safe in a sense that goes beyond compliance documentation.
At the same time, every robot that operates in a real environment faces a second, quieter challenge: staying operational. Dust, moisture, mechanical vibration, and chemical exposure are constant in the settings where humanoid robots will work. The components that seal joints, protect actuators, and absorb shock – consistently, over many years of operation – rarely appear in product demonstrations. Yet they represent some of the most critical design decisions a robotics engineer can make.
Covestro has been developing material solutions for both of these challenges across industrial applications – from automotive soft-touch surfaces to precision sealing in demanding machinery. Desmopan® Thermoplastic Polyurethanes (TPU), part of established portfolio of high-performance polymers from Covestro, is increasingly emerging as the material of choice for humanoid robot designers addressing the skin, grip, and protective layer challenges that define how these machines interact with people and endure in real environments.
A robot that works alongside people must earn their trust – physically, not just digitally. Desmopan® TPU is how we contribute to that trust: through surfaces that are safe, durable, and designed for human contact.
What makes a robot's surface earn human trust?
For humanoid robots that interact directly with people – passing objects, offering support, operating in care environments – the biocompatibility of surface materials is often a specification requirement, not an optional quality. Covestro offers Desmopan® grades assessed in accordance with ISO 10993, the international standard framework for the biological evaluation of materials intended for contact with the human body.
Relevant Desmopan® grades from Covestro are formulated without plasticizers. Plasticizer migration – the gradual leaching of added chemicals from a polymer to a contact surface – is a long-term concern of many flexibilized materials, particularly in sustained skin contact applications. A plasticizer-free formulation means the material's performance characteristics and its safety profile remain stable over the operational life of the robot. This matters particularly in environments where the same robot hand that grips industrial components also handle food, pharmaceutical products, or personal care items – applications that are well within the operational scope of service and care humanoid robots currently in development.
What if the entire robot surface could feel as human?
Gripping and tactile sensing address what the robot's hand does. The skin challenge in humanoid robotics extends the gripping and sensing of robot’s hand across the entire outer surface of the machine – the body panels, the joints, the areas of the robot that people brush against, lean into, or make casual contact with in shared spaces. For robots operating in care environments, public settings, or alongside children, these surfaces carry a different kind of requirement: they need to feel not just safe, but genuinely comfortable. Warm to the touch. Forgiving under accidental contact. Aesthetically credible. This is where two further material solutions from the TPU portfolio enter the humanoid robotics design conversation: Desmopan® TPU grades for the production of leather like materials and Desmopan® AIR for thermoplastic cushioning.
Desmopan® TPU enables the production of synthetic leather materials with a surface quality and tactile profile that approaches the warmth and texture of natural leather – without the material inconsistency, the maintenance requirements, or the supply chain complexity that natural leather introduces at production scale. For humanoid robots, these TPU-based leather materials are suitable solutions for the outer shell: a surface layer that is soft and aesthetically refined, yet durable enough to resist the wear and surface degradation that comes from daily contact in active environments. The material offers excellent resistance to scratching and abrasion – a critical property for surfaces that will be touched, and handled continuously. Texture and color can be customized across a wide range of aesthetics, giving robot designers meaningful creative latitude in how the machine is perceived and accepted.
Desmopan® AIR thermoplastic cushioning addresses the structural layer beneath the outer skin – the interface between the robot's rigid chassis and its surface layers that determines how contact forces are absorbed and distributed. Where traditional approaches rely on foam inserts or rigid shells with limited resilience, Desmopan® AIR uses a three-dimensionally printed or structured thermoplastic cushioning architecture that can be tuned for specific compression and energy absorption characteristics. Weight is a central advantage: the open structure of the Desmopan® AIR cushioning system achieves effective force distribution at substantially lower density than solid alternatives, contributing to the weight reduction that directly benefits humanoid robot’s power budget, range of movement, and dynamic performance. With Desmopan® AIR technology the production of the robot shell-system is simplified and safer as no foaming step is needed.
The combination of TPU-based synthetic leather surface materials and Desmopan® AIR cushioning substrate represents a complete soft-shell system for humanoid robot body – one that manages aesthetics, tactile quality, impact absorption, and weight in an integrated architecture. Both materials can be customized for the flexibility and surface behavior required by the specific geometry and movement profile of the robot panel or joint cover they are applied to.
The practical implication for humanoid robot designers is a material pathway from fingertip to body shell that draws on a coherent, compatible portfolio rather than a patchwork of multiple suppliers and material chemistries.
At Covestro, we develop for human contact. With Desmopan® TPU, we give designers a material that is versatile enough to enable the right solution — and durable enough to deliver it, interaction after interaction.
How do you keep precision components alive in real-world environments?
The robot that looks confident in a demonstration but fails in deployment typically does not fail because of the AI or the actuator. It fails because something let the outside world in – or because vibration that should have been absorbed reached a component that could not tolerate it.
Humanoid robots operating in real environments face conditions that precision machinery is designed to be protected from. Fine dust in manufacturing facilities finds its way into every gap. Cleaning agents used in food processing or healthcare environments are corrosive to materials not specifically formulated to resist them. Temperature variations between seasons expand and contract every material in the robot's structure, repeatedly stressing every interface and seal. And the robot's own movement – the actuation of joints and motors – generates vibration that, if not managed, propagates through the structure as a source of accelerated wear.
Desmopan® TPU grades from Covestro combine thermoplastic processability with sealing performance, offering a solution where both manufacturing efficiency and end-of-life considerations – such as recyclability and sustainability – are critical design parameters. Compression set – the tendency of a material to permanently deform under sustained compressive load, which determines how well a seal maintains contact pressure at its sealing interface – is a primary specification for sealing applications, and selected Desmopan® grades achieve very low compression set values at ambient conditions. Chemical resistance to oils and greases, gear lubricants, and hydraulic fluids, most commonly used in humanoid robot joint systems is a characteristic of the polyurethane chemistry that underpins the Desmopan® platform.
The processing advantage is consequential. Injection-molded TPU seals can be produced in the same manufacturing infrastructure as the other thermoplastic components in the robot’s assembly. They can be over molded directly onto polyamide and polycarbonate joint housings without adhesives, creating a strong bond, integral to the part rather than an assembly step added afterward. The result is a sealing solution with fewer production steps and a manufacturing process that integrates naturally into the broader polymer supply chain for humanoid robotics.
For vibration management of power units and robot’s own movement, Desmopan® is well suited due to its inherent damping properties. In addition, Covestro’s foamed Desmopan® grades extend the range of possibilities for both sealing and vibration-damping applications. Foamed TPU achieves lower densities reducing the weight contribution of damping elements in a structure where weight directly affects power consumption and dynamic performance – while maintaining the elastic recovery and compression behavior that effective vibration absorption requires. The dynamic modulus of Desmopan® can be tuned through material grade selection, giving designers a controllable paramter for matching damping behavior to the specific frequency profile of the joint or component being protected, thereby broadening design freedom.
What happens to these materials when the robot reaches end of life?
Materials choices made in product design today determine recyclability profiles for the end-of-life products of tomorrow. For humanoid robot OEMs operating under extended producer responsibility frameworks, or committed to circular economy targets, the thermoplastic nature of Desmopan® TPU is a relevant property from the earliest stages of design.
Thermoplastic materials can be reprocessed at end of life and returned to the material stream while thermosets cannot be reprocessed in the same way. The sealing, dampening, and soft-touch surface components that are specified in Desmopan® TPU today will be components that are recyclable when the robot reaches end of life – a property that is increasingly important part of the value calculation for material selection decisions, not a secondary consideration.
The humanoid robots entering service in the coming years will be evaluated not only on what they can do, but on how they do it – how safely they interact with people, how reliably they perform in real environments, and how responsibly they are designed for the full arc of their operational life. The materials at their surface and inside their joints are not peripheral decisions. They are the point where engineering specification and human experience meet.
