Mechanical stretchability of screen-printed Ag nanoparticles electrodes on polyurethane substrate for stretchable interconnectors and thin film heaters

We report on mechanical flexibility of screen printed Ag nanoparticles (NPs) electrode on a transparent and stretchable polyurethane (PU) substrate to use as stretchable electrodes in wearable electronics. Using lab-made inner/outer bending, rolling, folding and stretching testers, the feasibility of directly patterned Ag NPs electrodes were comprehensively investigated. Patterned Ag NPs electrode on stretchable PU substrate showed a sheet resistance of 3.49 Ohm/square, critical inner/outer bending radius of 3mm, rolling radius of 3 mm and strain of 20%, which are acceptable as stretchable interconnectors for wearable electronic devices. We demonstrated promising applications of the screen-printed Ag NP electrode as stretchable interconnectors for light emitting diodes (LEDs) and stretchable electrode for stretchable thin film heaters (TFHs). Successful operation of commercial LEDs on the 70% stretched Ag NPs electrode and saturation temperature of 70 ^◦ C on the Ag NP electrode-based TFHs attached on human skin exhibited the potential of screen printed Ag NPs electrodes as high performance stretchable electrodes for cost-effective printable and wearable electronics.