The Design, Optimization and Experimental Framework for Pressure Sensors

Abstract

This thesis explores the fabrication and optimization of thin-film pressure sensors (TFPS) using graphite (Gr) as the active material and polyvinyl alcohol (PVA) as the binder. Three TFPS samples were fabricated and tested under both lowpressure (below 800 Pa) and high-pressure (1 MPa to 5.5 MPa) conditions, with key performance parameters—sensitivity, limit of detection (LOD), response time, and stability—evaluated. Results indicated that the sensors demonstrated high sensitivity in the high-pressure range but exhibited limited sensitivity for low-pressure range. Sensitivity values in the low-pressure range were 6.8×10−5kPa−1±1.8×10−4kPa−1 2.1 × 10−5kPa−1±1.9 × 10−4kPa−1 and 3.4 × 10−5kPa−1±1.8 × 10−4kPa−1, while in the high-pressure range, they were 1.9 × 10−4kPa−1±2.9 × 10−5kPa−1, 1.6 × 10−4kPa−1±2.6 × 10−5kPa−1 and 1.5 × 10−4kPa−1±3.0 × 10−5kPa−1 for samples 1, 2, and 3, respectively. The LOD ranged from 6.6 × 10−2 kPa±2.8 × 10−2 kPa to 5.6 × 10−2 kPa±2.9 × 10−2 kPa in the low-pressure range and 1.7 × 10−3 kPa ±8.2×10−9 kPa to 2.0×10−3 kPa ±9.5×10−9 kPa in the high-pressure range. Stability tests suggested potential applications in health monitoring and insole pressure sensing. However, the response time (82 ms) of the fabricated sensors is relatively slow. Proposed improvements include the use of automated systems to reduce human error and alternative coating methods to improve film homogeneity. As well as, incorporating an additional component between the CCAF and the film to allow better stress distribution within the material; since the rigidity of the film promotes slippage between the CCAF and the film. Additional testing methods to observe the unloading behavior of the film in respect to pressure and relative resistance could contribute to further observations not covered. The study, however, highlights the feasibility of using accessible, low-cost materials for TFPS fabrication, offering insights for future sensor optimization