Indium Tin Oxide (ITO) nanoparticle ink formulations were tested to get better conductivity to make prototypes. ITO ink formulation was printed as same as AZO films. After the forming gas annealing, ITO thin films showed a dramatic decrease of sheet resistance compared to the AZO thin films with the same amount of solid content. The sheet resistance was around 75 ohms/square which is good enough to make transparent heater prototypes. This is early stage prototype of transparent heater prototype which was made with 4 cm * 8 cm ITO thin film. The heater shows more than 90 % of transparency for visible light.
These prototypes were tested at different voltages. Also, full heating and cooling cycles were investigated. The heating and cooling cycle was highly reproducible. Following graph shows the heating and cooling cycles when it was operate at 24 V. It reached ~ 62 0C as maximum temperature in less than 2 minutes.