Fabrication and characterization of CNT-reinforced re-entrant lattice cardiac patches using flexible photocurable resin for enhanced flexibility and conductivity

Abstract Cardiovascular diseases responsible for approximately 19.8 million deaths annually, necessitate advanced cardiac repair materials that exhibit mechanical compliance, electrical functionality, and stability under dynamic deformation to match the native myocardium. This study reports the fabrication and characterization of CNT-reinforced re-entrant lattice cardiac patches using a flexible photocurable resin and DLP-based additive manufacturing by carbon nanotubes (CNTs) to realize the mechanical flexibility and inherent strain-sensing behavior. Re-entrant lattice geometries were designed based on auxetic principles to promote lateral expansion and strain redistribution under tensile deformation. The mechanical test demonstrated that pure resin patches have a higher tensile strength (0.33–0.35 MPa), but limited extensibility, whereas CNT-reinforced patches have a low stiffness (0.015–0.05 MPa), but a high elastic deformation and energy dissipation. SEM, XRD, and FTIR analyses established the CNT dispersion was homogeneous, crystalline of the graphitic was preserved, and the interfacial between the polymer and CNT were strong. The CNT-reinforced patches exhibited stable piezoresistive behavior under both static and cyclic tensile deformation. Geometry-dependent electromechanical sensitivity was observed, with gauge factors ranging from 2.9 to 5.3. Cyclic loading tests showed repeatable resistance responses with over 95% signal recovery and minimal hysteresis. The integration of re-entrant lattice geometry, CNT reinforcement, and commercial flexible photocurable resin provides a mechanically compliant and electrically responsive platform has potential for self-sensing cardiac patch applications.