Tyre Pressure Monitoring System Using FSR and Flexible NFC

This paper presents a low-cost pressure monitoring system that uses a Force-sensing resistor integrated into an NFC tag. The system achieves accurate pressure monitoring through a Force-Sensing Resistor connected to an astable multivibrator circuit, which utilises a low-power ICM7555 timer. The relationship between frequency and pressure is determined through a cost-effective calibration method. This relationship is used by a low-power 8-bit microcontroller to read the frequency and convert it into pressure readings, and transmits data to the NFC IC via the I2C protocol, making them accessible to any device equipped with an NFC reader. The prototype, built on a FR4 substrate, that incorporates a Class 4 ISO/IE $C$ 14443 antenna built on Polyimide substrate which is linked to the NFC IC (N $T$3H2111). Using a flexible substrate for the proposed system ensures that the tyres remain undamaged when the system is deployed, and because it is flexible, it can be deployed at different places at ease. The system underwent testing using pressure ranges like those found in a mountain bike, varying from 0.5 to 2.2 bar.