High-Geometrical-Accuracy Embroidery Process for Textile Antennas With Fine Details

An embroidery process with high geometrical accuracy is presented for antennas with fine details. Previous embroidery processes employed thicker threads, leading to resolution not better than 1 mm. Therefore, fine details (e.g., sharp corners) could not be realized, and geometrical accuracy was low, viz. > 1 mm. To overcome these limitations, in this letter we: 1) employ much thinner E-fibers to enable the "printing" of sharp corners, and 2) increase embroidery density to boost surface conductivity. Two Liberator E-fibers were tested: 1) 40-strand (diameter = 0.27 mm), and 2) 20-strand (diameter = 0.22 mm). Embroidery density was optimized using double-layer stitching of 7 threads/mm. To validate our embroidery approach, we fabricated and tested a dipole antenna with intricate details operating at 2.4 GHz. This design could not be formerly "printed" on textiles. Both E-fiber (40/20-strand) prototypes exhibited excellent performance, comparable to that of copper antennas. The achieved geometrical accuracy was similar to 0.3 mm (viz. 3 times better).