Multifunctional porous soft composites for bimodal wearable cardiac monitors

Wearable heart monitors are crucial for early diagnosis and treatment of heart diseases in non-clinical settings. However, their long-term applications require skin-interfaced materials that are ultrasoft, breathable, antibacterial, and possess robust, enduring on-skin adherence-features that remain elusive. Here, we have developed multifunctional porous soft composites that meet all these criteria for skin-interfaced bimodal cardiac monitoring. The composite consists of a bilayer structure featuring phase-separated porous elastomer and slot-die-coated biogel. The porous elastomer ensures ultrasoftness, breathability, ease of handling, and mechanical integrity, while the biogel enables long-term on-skin adherence. Additionally, we incorporated ε-polylysine in the biogel to offer antibacterial properties. Also, the conductive biogel embedded with silver nanowires was developed for use in electrocardiogram sensors to reduce contact impedance and ensure high-fidelity recordings. Furthermore, we assembled a bimodal wearable cardiac monitoring system that demonstrates high-fidelity recordings of both cardiac electrical (electrocardiogram) and mechanical (seismocardiogram) signals over a 14-day testing period.