Highly Transparent, Self-Healable Stretchable Conductors for Skin-Attachable Transparent Bioelectronic Sensors and Synesthesia Displays

Transparent and stretchable conductors are essential components for next-generation soft electronics. However, simultaneously achieving high electrical conductivity, optical transparency, stretchability, and self-healing capability within a single conductor is challenging, because optical clarity and electrical performance are often traded off. Here, we introduce a multifunctional transparent stretchable conductor consisting of a micropatterned liquid metal (LM) mesh embedded within a self-healing elastomeric matrix. This innovative architecture delivers high optical transparency (81.6%), exceptional stretchability (>1,000%), low sheet resistance (2.5 Ω sq^-1), and robust self-healing functionality (86.4% toughness restoration at 60 °C for 2 h). The patterned LM network maintains continuous electrical conductivity under extreme and repeated mechanical deformation, while the elastomer matrix rapidly restores its structural integrity with only thermal stimuli. To demonstrate practical applicability, this transparent stretchable conductor is implemented in wearable sensors, enabling stable electrocardiogram (ECG) and electromyogram (EMG) signal acquisition under repeated deformation. Additionally, integration as a transparent electrode in a stretchable, alternating current-driven display yielded a peak luminance of 2,500 cd m^-2 with synchronized acoustic emission (∼73 dB). These findings highlight the significant potential of the conductor for robust and multifunctional wearable and optoelectronic devices capable of operating reliably in dynamic, deformable environments.