Passive wireless sensing using SWNT-based multifunctional thin film patches

This study presents a high-performance inductively coupled multifunctional carbon nanotube thin film sensor for structural monitoring applications. A versatile layer-by-layer self-assembly sensor fabrication technique is employed to encode different sensing mechanisms (e.g., strain and corrosion/pH) within one homogeneous thin film structure. Judicious selection of various polyelectrolyte species, along with the incorporation of carbon nanotubes, permits multifunctional sensing. Upon deposition of these thin films on miniature planar coil antennas to form a resonant circuit, a passive wireless sensor is realized. Unlike traditional cabled or wireless sensing systems, the proposed passive sensor does not require a constant power source, thereby rendering it ideally suited for embedment within structures.