Tailoring fractal structure via 3D printing to achieve flexible stretchable electrodes based on Ecoflex/CNT/CF

Flexible electrodes are crucial for the widespread application of flexible electronics. Flexible stretchable electrodes are a research hotspot for finding a solution for the inability of flexible electrodes to withstand large deformations. In this study, the suitability of silicone rubber (Ecoflex), carbon nanotube (CNT), and carbon fiber (CF) composite materials for flexible devices and their ratios were evaluated for the first time. 3D-printed electrodes based on fractal structures with tensile insensitivity and high linearity were prepared to achieve integrated stretching of flexible devices. To demonstrate the benefits and impact of fractal structures on electrode performance, we fabricated flexible stretchable electrodes with four distinct designs: horseshoe, U-shaped, rectangular, and triangular. The tensile properties of these structures were theoretically calculated and validated through simulations and experiments; the horseshoe design proved to be the softest. Furthermore, we evaluated the performance of the prepared third-order flexible stretchable electrodes for gas-detection applications and achieved promising results, demonstrating the significant potential of these electrodes for wearable gas detection.