Multimodal Hydrogel Bioelectronics for Closed-Loop Diagnosis and Treatment of Cardiac Diseases

This study developed a multimodal hydrogel multielectrode array (MHMHEA) for conformal epicardial monitoring, mechanical strain sensing, electrophysiological mapping, and targeted electrical stimulation. The device was fabricated through integrated multi-material 3D printing using adhesive, conductive, strain-sensing, and encapsulation hydrogel layers. The hydrogel system was engineered to combine tissue-like mechanical compliance, with a reported Young’s modulus of approximately 430 kPa, with strong tissue adhesion and electrically conductive PEDOT:PSS-based components. The MHMHEA tolerated bending, crumpling, and stretching while maintaining robust adhesion to cardiac tissue and stable electrical performance. Its conductive polymer hydrogel electrodes maintained high conductivity and charge-storage capability, while integrated strain sensors produced reproducible resistance changes over strains from 10% to 40%, detected strains as small as approximately 1%, and remained stable during 1000 repeated deformation cycles. In rat studies, the eight-channel array simultaneously recorded epicardial ECG signals and spatially resolved myocardial strain, allowing healthy hearts, myocardial infarction, and left ventricular hypertrophy to be distinguished through characteristic electrical and mechanical patterns. The system also delivered localized electrical stimulation to infarcted rat hearts. After four weeks, stimulated animals showed improved ventricular dimensions, ejection fraction, and fractional shortening compared with untreated myocardial infarction controls. Overall, the study demonstrates a conformal implantable hydrogel bioelectronic platform capable of integrating cardiac electrical and mechanical diagnosis with localized therapeutic stimulation in a closed-loop framework.