Metallization Techniques for Wearable Textile Electronics

Wearable electronics must be both flexible and robust so that they can be form fitting and reliable. The first of these were fabricated with printed conductors on rubber, plastic, and other polymer substrates. More recently, conductive textiles have been preferred due to their 1) inherently flexible and lightweight physical properties, and 2) low-loss, low-dielectric electrical properties. However, a variety of challenges persist when implementing wearable textile electronics, with necessary trade-offs between conductivity, durability, and flexibility. Consequently, there is still a need to develop optimal metallization approaches. In this paper, six different textile-compatible metallization techniques are presented. These include adhering copper tape, silver paint, silver thread, silver-painted silver threads (SPST), copper mesh, and silver-painted copper mesh (SPCM) to a denim stack-up. Microstrip transmission line (TL) prototypes were fabricated with each method, and analyzed to determine which textile-compatible metallization technique had the best performance in comparison to a TL on standard printed circuit board (PCB). Measurements show that the denim TL with SPST conductors had the smallest losses versus the PCB standard, with only an average loss of 0.03 dB/cm from 0.5 to 3 GHz.