Temperature sensor realized by inkjet printing process on flexible substrate

• Flexible temperature sensor was realized by inkjet printing process on Kapton substrate.
• The jetting parameters were optimized to obtain evenly distributed silver coating layers and a large meander forming the sensor.
• The Temperature sensor studied offers a good sensitivity, a good linearity and less than 5% hysteresis in extended measurement in the range of 20–60 °C.

The objective of this study is to realize a printed and flexible temperature sensor to achieve surface temperature measurement of the human body. The sensor is a thermistor composed silver (Ag) deposited on a Polyimide substrate (Kapton HN). The meander was patterned by inkjet printing with a drop-on-demand Jetlab4 (Microfab Technologies Inc.). The resistance temperature coefficients have been studied in the temperature range of 20–60 °C with a range of voltage between 0 and 1 V. The stability versus time has also been measured without a sensor layer protection. The sensitive area of the sensor, silver lines width and the gap between the electrical conductors were, respectively 6.2 cm2, 300 μm, 60 μm. The mean temperature sensor sensitivity found was 2.23 × 10−3 °C−1. The results show a good linearity and less than 5% hysteresis in the extended measurement.