New Advances in Antenna Design toward Wearable Devices Based on Nanomaterials

Abstract

Wearable antennas have recently garnered significant attention due to their attractive properties and potential for creating lightweight, compact, low-cost, and multifunctional wireless communication systems. With the breakthrough progress in nanomaterial research, the use of lightweight materials has paved the way for the widespread application of wearable antennas. Compared with traditional metallic materials like copper, aluminum, and nickel, nanoscale entities including zero-dimensional (0-D) nanoparticles, one-dimensional (1-D) nanofibers or nanotubes, and two-dimensional (2-D) nanosheets exhibit superior physical, electrochemical, and performance characteristics. These properties significantly enhance the potential for constructing durable electronic composites. Furthermore, the antenna exhibits compact size and high deformation stability, accompanied by greater portability and wear resistance, owing to the high surface-to-volume ratio and flexibility of nanomaterials. This paper systematically discusses the latest advancements in wearable antennas based on 0-D, 1-D, and 2-D nanomaterials, providing a comprehensive overview of their development and future prospects in the field.

Keywords: carbon nanotubes; graphene; nanomaterials; silver nanowires; wearable antenna; wearable device.

Figure 2

(i) (a) Photograph of the antenna produced using inkjet printing; (b) demonstration of the flexibility of inkjet-printed antenna [41]. (ii) (a,b) The cross-sectional and locally enlarged scanning electron microscope (SEM) images of conductive ink on a PDMS substrate; (c,d) SEM images and schematic representation of stages of silver particle realignment in polymer matrix during globular rupture [50]. (iii) Different states of the antenna: (a) free space, (b) bending radius R = 35 mm, and (c) attached to the right arm [52].

Figure 3

(i). SEM images of AZO at different substrate temperatures (a) 30 ℃, (b) 100 ℃, (c) 150 ℃, and (d) 200 ℃ [56]. (ii) Patch antenna design and testing configuration; (a) transmission line-fed patch antenna geometry and dimensions; (b) CNT patch antenna dimensions at each of the three target frequencies; (c) blow-up of the CNT antenna shown in (d); and (d) experimental set-up for radiation efficiency measurements inside the reverberation chamber [67]. (iii) (a,b) SEM images of AgNWs and composite film after annealing at 300 °C for 1 h [57].

Figure 4

(i) (a) Illustration of a textile device with sensing and display capabilities; (b) illustration of the textile device with various laminated layers: multilayer graphene, fabric separator, and back electrode layer; (c) representative examples of fabricated devices on various textile materials such as woven cotton fabric and nonwoven high-density polyethylene fabric. Continuous conductive textiles or patterned gold electrodes can be used as the back electrode [93]. (ii) (a) Transmission electron microscope image of graphene oxide; photographs of an FGF antenna sensor attached to (b,c) the back of the hand joint based on paper; and (d,e) the inside of the elbow based on PET [87].

Figure 1

Nanomaterials are commonly used in wearable antennas.