Transparent Oxide/Metal/Oxide Thin Film Heater With Integrated Resistive Temperature Sensors

In this paper we present a device integrating on a single glass substrate a transparent heater and two resistive temperature sensors. Both heater and sensors are constituted by ITO/Au/ITO stacked film, whose thicknesses have been optimized in order to achieve at the same time good electrical conductivity (about 106 S/m) and high transparency degree (higher than 80%) in the visible region of the spectrum. A double-spiral design has been chosen for the heater in order to achieve a uniform temperature distribution on a large area. Indeed, this geometry ensures a temperature variation of ±1.4 °C in a 2.8 cm diameter circle. For the resistive temperature sensors, a distributed meander-shaped geometry ensures temperature sensitivity as high as 0.12 $\text{k}\pmb \Omega / ^{\circ }\text{C}$ . The proposed device shows therefore the capability to work as a large-area transparent heater introducing the possibility to perform a precise control of the substrate temperature.