Direct ink writing printed flexible double-layer staggered woodpile structure for multi-band compatible absorption of gigahertz and terahertz waves

Soft multi-band compatible electromagnetic wave absorbers have wide applications in 6G communication, radar stealth, detection instruments, and radio astronomy. In this context, a kind of double-layer staggered woodpile absorber is designed and manufactured by the direct ink writing (DIW) technology with a composite ink system composed of reduced graphene oxide (RGO)/spherical carbonyl iron (SCI) and polydimethylsiloxane (PDMS). The as-prepared absorber shows compatible absorption in both microwave and terahertz frequency bands. The effective absorption bandwidth (EAB) and minimum reflection loss (RLmin) reach 8.24 GHz and −52.2 dB at a thickness of 3.2 mm, respectively. In the terahertz band (0.5–3.5 THz), it shows effective absorption (absorption rate greater than 99 %) and achieves RL < -20 dB throughout the entire tested band. In addition, the double-layer staggered woodpile absorber has good flexibility and can be conveniently used for curved substrates. This work enables the potential for rapid manufacturing of flexible and compatible absorbing devices through DIW 3D printing for applications in 5/6G communication, military stealth and flexible wearable intelligent devices.