High-performance stretchable conductive composites for washable textile electronics via intermolecular interaction control

Abstract

Stretchable interconnects are essential for wearable, healthcare, and robotics technologies. While various electrode materials and architectures have been explored, developing stretchable composites that simultaneously achieve high electrical conductivity, strain stability, and strong adhesion remains challenging. High conductivity necessitates a high filler volume fraction, which increases viscosity, reduces electrical stability, and compromises adhesion during mechanical deformation. To address these limitations, we demonstrate stretchable conductive composites by incorporating short alkyl-chain dicarboxylic acids into Ag flake/silicone composites via a one-step blending process. This approach replaces the original lubricants on Ag flakes, improving dispersion and optimizing inter-flake attractive interactions. Both experimental and simulation results confirm that tuning the dicarboxylic acid chain length is critical for enhancing conductivity and network stability. Compared to composites with pristine Ag flakes, the addition of 0.5 wt% succinic acid significantly decreases the electrical resistivity by up to 5 orders of magnitude at 60 wt% Ag content and achieves a minimal resistivity of 5.4 x 10-5 Omega center dot cm at 75 wt% Ag, comparable to those of printable solder pastes or rigid epoxy-based adhesives with over 80 wt% Ag content. Despite the lower Ag content, these composites exhibit excellent strain stability, washability, strong adhesion to stretchable substrates, and high performance in wearable devices such as ECG, EMG, and EOG sensors, highlighting their potential for stretchable and textile-based electronics.