Key Takeaways & Executive Findings
- •• • Record-high electromechanical sensitivity of 360 MPa⁻¹ achieved in SBE-1, exceeding the previous benchmark of 110 MPa⁻¹ by over 3-fold, enabling low-voltage actuation for practical soft robotics. • • SBE-1 exhibits an ultralow Young's modulus of ~10 kPa and a relative dielectric constant of 3.6, simultaneously addressing the trade-off between mechanical softness and dielectric performance. • • Under 35 V μm⁻¹ without prestretching, SBE-1 achieves 90% area strain, outperforming pure phases and other DEAs, demonstrating superior actuation performance at low fields. • • SBE-based artificial muscles deliver a power density of 2250 W kg⁻¹ at resonance (>200 Hz), surpassing natural muscle and prior DEA artificial muscles, enabling high-frequency, high-power applications.
Abstract
Dielectric elastomer actuators (DEAs) are promising artificial muscle technologies due to their large actuation strains, high energy density, and fast response. However, their practical application is hindered by a trade-off between increasing the relative dielectric constant (εr) and decreasing the Young's modulus (Y), which limits electromechanical sensitivity (εr/Y) to below 110 MPa⁻¹. Here, we report a hetero-cross-linking strategy to fabricate a semiseparated biphasic bicontinuous dielectric elastomer (SBE) using two commercial silicone elastomers: Elastosil P7676 (mechanical phase, M-phase) and Sylgard 170 (dielectric phase, D-phase). The M-phase provides an ultralow Young's modulus (~10 kPa), while the D-phase offers a high dielectric constant (3.6). With only 10% D-phase content (SBE-1), the material achieves a record-high electromechanical sensitivity of 360 MPa⁻¹. Under an electric field of 35 V μm⁻¹ without prestretching, SBE-1 exhibits a 90% area strain, significantly outperforming pure phases and previously reported DEAs. The interpenetrating phase structure also enhances breakdown strength. SBE-based artificial muscles demonstrate large displacement at high frequencies, achieving a power density of 2250 W kg⁻¹ at resonance (>200 Hz), surpassing natural muscle and prior DEA artificial muscles. A human-like robotic arm with one rotational joint and four pure-shear SBE-based artificial muscles was developed, capable of extending and bending actions. This work provides a versatile strategy for high-performance DEAs, advancing soft robotics applications.
1. Introduction
Dielectric elastomer actuators (DEAs) are a leading artificial muscle technology, offering large actuation strains, high energy density, and rapid response. However, their widespread adoption is constrained by a fundamental trade-off: increasing the relative dielectric constant (εr) via chemical modification or filler incorporation typically raises the Young's modulus (Y), while reducing Y through plasticizers or network optimization often compromises breakdown strength. This trade-off caps electromechanical sensitivity (εr/Y) below 110 MPa⁻¹, insufficient for many practical applications.
The hetero-cross-linking strategy presented here directly addresses this bottleneck by creating a semiseparated biphasic bicontinuous structure. By combining two commercial silicone elastomers with distinct crosslinking mechanisms—Elastosil P7676 (side-chain) and Sylgard 170 (main-chain)—the material achieves an ultralow modulus in the mechanical phase and a high dielectric constant in the dielectric phase, without sacrificing breakdown strength. This approach decouples the conflicting requirements, yielding a record-high sensitivity of 360 MPa⁻¹ and enabling large actuation strains at low electric fields, thereby advancing the practicality of DEA-based artificial muscles.
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Hao Xu, Zhekai Jin, Chao Wang (2026). A Hetero-Cross-Linking Strategy for Versatile Artificial Muscles with Superior Electromechanical Sensitivity. SCIENCE CHINA Materials. https://doi.org/10.1007/s40843-025-3970-1
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Frequently Asked Questions
What is the maximum electromechanical sensitivity achieved and how does it compare to previous DEAs?
The SBE-1 formulation achieves a record-high electromechanical sensitivity of 360 MPa⁻¹, which is more than three times the previous benchmark of 110 MPa⁻¹. This is accomplished by combining an ultralow Young's modulus (~10 kPa) with a high dielectric constant (3.6), overcoming the traditional trade-off.
How does the hetero-cross-linking strategy improve breakdown strength despite the low modulus?
The semiseparated biphasic bicontinuous structure creates dielectric barriers at the interphase, which enhance the breakdown strength. This allows the material to operate at higher electric fields without failure, as demonstrated by the 90% area strain achieved at 35 V μm⁻¹ without prestretching.
What are the scalability and cost implications of using commercial silicone elastomers?
The strategy utilizes two commercially available silicone elastomers (Elastosil P7676 and Sylgard 170), which are cost-effective and readily scalable. The fabrication process does not require complex chemical synthesis, making it amenable to industrial production.
Can the SBE-based artificial muscles operate at high frequencies for practical applications?
Yes, the SBE-based artificial muscles achieve a power density of 2250 W kg⁻¹ at resonance (>200 Hz), surpassing natural muscle and prior DEA artificial muscles. This high-frequency capability is essential for applications requiring rapid and repetitive motion, such as robotic arms.
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