A Fully-Printed Organic Smart Temperature Sensor for Cold Chain Monitoring Applications

This paper presents a printed smart temperature sensor on RFID manufactured with organic materials. The system-on-foil exploits printed resistors and a time-based printed OTFT interface to convert temperature to a PWM representation and enable wireless RF communication at 13.56 MHz. The system is also equipped with a dedicated harvesting circuit for wireless power transfer, allowing stand-alone operation. The smart sensor achieves 0.27 KRMS resolution for a 2 $s$ conversion time, a resolution FOM of 294 10-6·J· K2 and a 3 sigma inaccuracy of ±1.2° C over the food monitoring temperature range 3° C to 27° C, after systematic non linearity removal and 3-point calibration. These results demonstrate that inexpensive electronic devices suitable for fresh food monitoring applications can be developed with unipolar printed organic transistor technologies, allowing e.g. integration of smart sensors in food packaging material.