Ultrathin and ultrastrong hydrogel membranes enable conformal bioelectronics

Researchers have developed an ultrathin yet ultrastrong hydrogel membrane that can serve as a robust and conformal interface between electronic devices and biological tissues, opening new opportunities for wearable and implantable bioelectronics.

Hydrogels are widely regarded as promising materials for bioelectronic applications because of their high water content, tissue-like softness, and biocompatibility. However, a longstanding challenge has been to reconcile mechanical robustness with the flexibility required to conform to complex three-dimensional (3D) biological surfaces. Conventional ultrathin hydrogel films can achieve good conformability, but they are often mechanically fragile and difficult to handle in practical applications.

In the new study, the research team reports a biomimetic design strategy that enables hydrogel membranes with a thickness of approximately 10 μm to exhibit an exceptional combination of properties, including high tensile strength (~13.65 MPa), high fracture toughness (up to ~21,573 J/m²), and low initial stiffness comparable to biological tissues. These characteristics allow the membranes to maintain structural integrity while conforming intimately to soft and irregular organ surfaces.

The key to this performance lies in a self-organized microfibrillar network inspired by natural load-bearing tissues. By introducing polyphenol-based crosslinkers, the researchers reconfigured the topology of the nanofiber network, strengthening the connections between fibrils while reducing overall connectivity. This unique structural arrangement enables strain-stiffening behavior, in which the material becomes stronger under deformation, similar to biological tissues such as skin.

“This work shows that we can overcome the traditional trade-off between softness and strength in hydrogels,” said Dr. Mingze Sun, co-first author of the study. “By engineering the microstructure of the fibrillar network, we are able to achieve materials that are both mechanically robust and highly conformable.”

Dr. He Zhang, also a co-first author, added, “The ultrathin format is particularly important for bioelectronic interfaces, as it allows seamless integration with complex 3D tissues while maintaining stable performance over time.”

Importantly, the hydrogel membranes are compatible with standard microfabrication processes and can integrate a wide range of electronic components. The team demonstrated the incorporation of conducting polymers and wafer-fabricated sensors into the hydrogel platform, enabling multimodal physiological sensing and stimulation. Applications demonstrated in the study include epidermal electronics for recording electrocardiogram (ECG) and electromyography (EMG) signals, as well as implantable interfaces for neural stimulation and recording.

 In animal experiments, the ultrathin hydrogel membranes achieved seamless contact with nerve tissues without the need for sutures or adhesives, improving signal quality and reducing stimulation thresholds compared with thicker hydrogel devices. The materials also exhibited favorable biocompatibility, with reduced inflammatory responses and improved neuronal health in long-term implantation studies.

Professor Xu note that this work establishes a general strategy for designing soft materials that combine high strength, toughness, and compliance through topological engineering of fibrillar networks. Beyond bioelectronics, the approach may be applicable to a broad range of fields, including tissue engineering, energy devices, and soft robotics.