Highly Sensitive Parylene C-Based Flexible Pressure Sensors for Wearable Systems

Flexible pressure sensors based on piezoelectric materials are being extensively investigated, but the potential of Parylene C in this application has rarely been explored, even though it has superior electrical insulation, excellent chemical inertness, flexibility, biocompatibility, and biostability. This study utilizes Parylene C as the piezoelectric layer, sandwiched between two copper electrodes and encapsulated with polyimide to fabricate a piezoelectric pressure sensor. Different Parylene C films of thicknesses comprising 10, 25, and 45 μm are prepared for the fabrication of the pressure sensors. The pressure sensors exhibit high sensitivities, with maximum pressure and frequency sensitivities of 87.62 and 580.95 mV Hz^-1. Interestingly, increasing the Parylene C thickness results in an ≈300% increase in output voltage at a frequency of 9 Hz due to improved piezoelectric coefficients (d ₃₃). This study further presents a fully flexible and biocompatible Parylene C-based dynamic pressure sensor array for integration in intelligent and smart gloves, enabling real-time pressure monitoring and wireless data transmission using low-range Bluetooth technology. This research should significantly advance the use of Parylene C in flexible wearable sensing technologies, with promise for applications in human-machine interfaces, healthcare, and other smart wearables.