Inkjet-Printed Titanium Carbide Nanoparticle-Based Flexible Bidirectional Flow Sensors for Flow-Aware Autonomous Systems

Bioinspired flexible flow sensors mimicking natural cilia enable ultrasensitive detection of fluid flows but are constrained by complex, multistep process flows, which result in high fabrication costs and long development times. Although high-resolution 3D printing enables complex structural fabrication, limitations in integrating functional materials into printed structures limit their use in smart structures, often necessitating multistep functionalization steps. In contrast, inkjet printing allows for maskless deposition of patterned functional materials for rapid prototyping of printed flexible sensing structures. Here, we report a cleanroom-free fabrication approach entailing inkjet printing of titanium carbide (TiC) nanoparticle ink to realize flexible, cilia-inspired piezoresistive cantilever flow sensors. A stable ink formulation ensures repeatable deposition of TiC-based strain gauges on flexible polymer substrates, thus enabling mechanically compliant sensors with robust sensing performance. The sensors exhibit a quadratic dependence on flow velocity, followed by saturation at higher velocities, consistent with finite element-based fluid–structure interaction simulations that elucidate the underlying strain-induced deformation mechanism. Additionally, the performance of the sensor is evaluated under both air and water flow conditions, thus underscoring its robustness across varied operating conditions and use cases. Finally, a pair of identical sensors was integrated onto a mobile robot platform to demonstrate flow-direction-aware navigation as a system-level validation of the proposed concept. The proposed fabrication approach, together with flow-aware autonomous mobile robot navigation demonstration, highlights the potential of inkjet printing as a scalable and alternative route for developing flexible piezoresistive sensors for next-generation engineered systems.