Laser‐Scribed Stretchable Liquid Metal Artificial Magnetic Conductor for SAR Reduction of Wearable UWB Antenna

Abstract This paper introduces the direct laser patterning of liquid metal, to develop stretchable artificial magnetic conductors (AMCs) aimed at minimizing specific absorption rate (SAR) in ultra‐wideband (UWB) wearable antennas. Laser provides rapid, efficient, and precise patterning with a high scanning speed of 4 m s −1 , achieving narrow gaps for liquid metal electrodes which strongly impact microwave performances of AMCs. To demonstrate the concept, a stretchable AMC is designed and fabricated for integration with a flexible UWB antenna, operating between 3.4 to 8 GHz in the UWB band, achieving SAR reductions by more than an order of magnitude while maintaining the antenna's return loss. This SAR reduction and low return loss are maintained even under stretching and bending conditions, with up to 50% strain and a minimum bending diameter of 25 mm. This protocol advances the liquid metal printing technology in the production of stretchable AMCs, and the achieved stretchable AMCs enhance the practical application of wearable antennas for wireless communications, particularly in scenarios where they operate in close proximity to the human body.