Screen‐Printed, Low‐Cost, and Patterned Flexible Heater Based on Ag Fractal Dendrites for Human Wearable Application

Abstract Achieving all‐printed, low‐cost, and large area electronic devices poses challenging requirements in employing printing technologies and conductive materials for flexible and wearable heaters. In this work, fully printed, scalable, and patterned flexible heaters based on Ag fractal dendrites (FDs) are fabricated through straightforward screen printing technology. The Ag FDs possess low sheet resistance with ≈0.83 Ω sq⁻¹ when sintered at low temperature of 60 °C. The Ag FDs are directly printed on thin polyethylene terephthalate substrate to manufacture flexible heaters, exhibiting excellent heating performance with the saturation temperature up to ≈135 °C and rapid response time within 35 s under 4 V DC voltage. In addition, the Ag FDs heaters present lower power consumption (≈209.67 °C cm² W⁻¹), which is significantly better than traditional indium tin oxides (ITO) heaters (≈88 °C cm² W⁻¹). The sheet resistance of the devices remains stable after 2000 bending cycles with a radius of 10 mm, indicating that the outstanding mechanize stability of the heaters. Moreover, a large area (12 cm × 5 cm) heater with designable pattern is developed and attached to human body, indicating a bright future in next‐generation fully printed and wearable heating electronics application.