Inkjet Printed Heating Elements Based on Nanoparticle Silver Ink with Adjustable Temperature Distribution for Flexible Applications

This article reports on developments in the manufacturing of heating elements by means of digital inkjet printing technology. The area coverage of the meander lines ranges from 34 lpi (lines per inch) to 51 and 102 lpi, which mainly influences the temperature distribution and homogeneity. Furthermore, the line width of the meander lines is varied between 250, 500, and 1000 mm. All heating elements are deposited by single-pass printing of a nanoparticle silver ink with subsequent thermal sintering on a standard flexible polymer film, to demonstrate that inkjet printing allows the manufacturing of printed thin devices also on low-cost material. The implementation of various designs allows the control of the temperature distribution and heat development. The printed structures are evaluated regarding their optical and electrical characteristics and their thermal performance is assessed using an infrared camera. This research has succeeded in developing bendable printed heaters, which reach homogeneous average temperature of 100 °C over an area of approximately 15 cm2 at a power supply of 12 V. The feasibility of the inkjet printed heaters is demonstrated by a long-term test over several days with negligible fluctuations in the area temperature and highest stability in the resistance.