Wireless Real-time Temperature Monitoring of Blood Packages: Silver Nanowires-embedded Flexible Temperature Sensor.

Real-time temperature monitoring of individual blood packages capable of wireless data transmission to ensure the safety of blood samples and minimize wastes has become a critical issue in recent years. In this work, we propose flexible temperature sensors using Ag nanowires (NWs) and a flexible colorless polyimide (CPI) film integrated with a wireless data transmission circuit. The unique design of the temperature sensors was achieved by patterning Ag NWs using a three-dimensional (3D) printed mold and embedding the patterned Ag NWs in the CPI film (p-Ag NWs/CPI film), which resulted in a flexible temperature sensor with electrical, mechanical, and temperature stability for applications in blood temperature monitoring. Indeed, a reliable resistance change of the p-Ag NWs/CPI film was observed in the temperature range of -20 °C to 20 °C with robust bending stability up to 5000 cycles at 5 mm bending radius. Real-time and wireless temperature monitoring using the p-Ag NWs/CPI film was demonstrated with the packages of rat blood. The result revealed that stable and consistent temperature monitoring of individual blood packages could be achieved in a blood box, which was mainly attributed to the conformal attachment of p-Ag NWs/CPI film to different packages in a blood container.