Flexible and Anisotropic Large-Area Piezoresistive Films for High Spatial Resolution Pressure Mapping

The development of advanced technologies like occupant detection systems (ODSs) in automotive applications, biometric and monitoring systems (BMS) in wearable electronics, and tactile sensing in human-machine interfaces (HMIs) all require reliable, high-resolution pressure sensors due to their ability to conform to surfaces and provide spatially resolved force measurements. This study presents the development of a flexible large-area piezoresistive sensor fabricated using a roll-to-roll process, featuring an anisotropic conductive film composed of nickel microcolumns embedded in a silicone matrix. The tunability of the piezoresistive film for operation under a broad stress range (up to 1.2 MPa) was evaluated through systematic electromechanical testing under uniaxial compression. A CO₂ laser ablation technique was employed to optimize interfacial contact resistance, enhancing sensor performance. Competitive benchmarking against commercial sensors highlighted the advantages of the proposed sensor in terms of sensitivity and operational range. Additionally, strain rate studies confirmed its stability and responsiveness under dynamic conditions, while cyclic loading tests revealed its robust performance over 100 test cycles. The unique microcolumnar morphology─which enables conductivity exclusively in the thickness direction while remaining insulating in-plane─was leveraged to effectively minimize electrical crosstalk. A 15 cm × 15 cm large-area pressure sensor with an array of 100 sensing points was designed to demonstrate high-resolution spatial mapping capabilities. Integrating a multiplexed readout system allowed efficient data acquisition and real-time spatial resolution useful for deployment of necessary actions in automotive safety systems. This work paves the way for scalable fabrication and establishes a foundation for the development of high-performance, flexible pressure sensors with high spatial resolution and mechanical reliability.