Bioinspired Durable Mechanical-Bioelectrical Dual-Modal Sensors Enabled by Mixed Ion-Electron Conduction and Mechanical Interlocking for Multifunctional Sensing

Abstract

Skin-like robust materials with prominent sensing performance have potential applications in flexible bioelectronics. However, it remains challenging to achieve mutually exclusive properties simultaneously including low interfacial impedance, high stretchability, sensitivity, and electrical resilience. Herein, a material and structure design concept of mixed ion-electron conduction and mechanical interlocking structure is adopted to fabricate high-performance mechanical-bioelectrical dual-modal composites with large stretchability, excellent mechanoelectrical stability, low interfacial impedance, and good biocompatibility. Flower-like conductive metal-organic frameworks (cMOFs) with enhanced conductivity through the overlapped level of metal-ligand orbital are assembled, which bridge carbon nanotubes (denoted as cMOFs-b-CNTs). Then, precursor of poly(styrene-block-butadiene-block-styrene)/ionic liquid penetrates the pores and cavities in cMOFs-b-CNTs-based network fabricated via filtration process, creating a semi-embedded structure via mechanical interlocking. Thus, the mixed ion-electron conduction and semi-embedded structure endow the as-prepared composites with a low interfacial impedance (51.60/28.90 kΩ at 10/100 Hz), wide sensing range (473%), high sensitivity (2195.29), rapid response/recovery time (60/85 ms), low limit of detection (0.05%), and excellent durability (>5000 cycles to 50% strain). Demonstrations of multifunctional mechanical-bioelectrical dual-modal sensors for in vivo/vitro monitoring physiological motions, electrophysiological activities, and urinary bladder activities validate the possibility for practical uses in biomedical research areas. This concept creates opportunities for the construction of durable skin-like sensing materials.