Bioinspired Interlocked Nanostructured Piezoresistive Composite for Monitoring of Renal Pelvic Pressure

Inspired by the structure of <i>Setaria viridis</i> and based on guidance of molecular dynamics simulations, a hierarchical nanospike structure on micrometer-sized coaxial fibers has been designed at the molecular scale. A piezoresistive composite membrane of in situ-grown PDA-PPy on a TPU@PES coaxial fiber has been prepared, exhibiting good anticreep performance, high sensitivity, and fast response. The matrix material is designed as coaxial fibers, which consist of an inner PES core that provides anticreep mechanical support and an outer thermoplastic polyurethane shell that offers a large specific surface area and rich graft reaction sites. The nanospike semiconductor phase constructs an interlocking structured composite by forming a multihierarchical conducting network. The piezoresistive sensor constructed with this composite exhibits ultrahigh sensitivity (27.1 kPa^-1) and quick response (23.1 ms response time and 26.3 ms recovery time). Furthermore, the chemical grafting process ensures a stable interface between the semiconductor phase and matrix material by creating covalent and hydrogen bonds. This interface not only prevents instability but also demonstrates excellent signal recovery performance and dynamic stability (10,000 cycles). Monitoring changes in renal pelvic pressure with a 3D-printed artificial renal pelvis was performed, confirming its practicality for medical monitoring.