Thermal Stability of a Fully Printed Ultra-Thin Organic Pre-Amplifier Circuit Meant for on-Skin applications

We report thermal stability measurement results for a fully printed ultra-thin (t=1μm) organic dual-use pre-amplifier circuit meant for on-skin applications. The pre-amplifier consists of 3 TFTs based on organic small molecule semiconductor polystyrene,2,7-dihexyl-dithieno [2,3-d;2‘,3’- d‘]benzo[1,2-b;4,5-b’]dithiophene (PS:DTBDT -C6), bias and feedback resistor based on poly(3-hexylthiophene) (P3HT) and printed feedback capacitor. The temperature dependency of the amplifier gain and threshold voltage (Vth) are measured in wide range of temperatures (21 to 60 ° C). In this temperature range the gain and Vth are observed to decrease 1,5 and 1 V, respectively. However, in the real use environment (attached on-skin) the expected temperature changes are significantly smaller because the ultra-thin pre-amplifier can use the body as a natural cooling system: although the ambient temperature may increase even 50°C, the expected temperature change on the device is only 6 °C and the changes in gain and Vth fall to neglectable level (0.24 and 0.18 V, respectively).