Direct-Write Printed Wearable Metasurfaces

Abstract

Direct-write printing was utilized in fabricating a wearable metasurface for frequency filtering at 6 GHz. Using radio frequency (RF) performance and sheet resistance, Rs as performance metrics, the printed metasurfaces were subjected to wash cycle and longevity testing. The metasurface was printed on two woven nylon industrial fabrics (70D (EX) and 200D (BW) thread masses) featuring a polyurethane (PU) coating on one side. Two conductive inks, CM127-48 (Creative Materials) and PE876 (Dupont) were printed on the fabrics and tested for Rs , RF performance, wash cycle stability, and longevity. Rs values for CM127-48 on EX and BW were similar (0.083±0.013 and 0.088±0.031 ohm/sq, respectively), while PE876 had higher Rs , on BW than EX (0.080±0.015 and 0.35±0.06 ohm/s). RF performance revealed that S21 magnitudes were at least −30 dB for all four ink–fabric combinations, in agreement with simulations. Wash cycle testing of PE876 on EX and BW revealed a comparable decrease in S21 magnitude for both fabrics. However, BW samples exhibited minimal shifts in peak frequency. Longevity tests on the four ink–fabric combinations demonstrated that S21 magnitudes were at least −29.5 dB, with the smallest change in magnitude for the CM127-48–EX sample. Materials selection may be tailored for various design goals in wearable electronics.