for the back device (FIGS. 3C-3D). These three orders of magnitude enhancement of signal transmission efficiency translate into lower power consumption and higher communication throughput. In particular, enhanced signal transmission enabled operation of the sensor at the lowest available transmit power setting (-55 dBm) without significant increase packet latency (FIG. 3E). In contrast, connection could not be established at power levels below -20~dBm in absence of the textile. Cumulative measurements show a rate of 4.53 packets per second for the radiative system and 31.86 packets per second for the metamaterial textile system at the lowest power setting where connection may be established (FIG. 3F). This enhancement translates directly to longer sensor battery lifetimes since wireless communication is typically among most energy demanding of sensor functions. 

[0097] Reference is now made to FIG. 3G, which is a schematic illustration of signal strength from sensors as a function of distance from the position of the smartphone, according to embodiments of the present disclosure. Data security is essential for the transmission of health and other personal data on body networks. FIG. 3G illustrates the change in signal strength from the sensors as a function of distance from the abdomen of the user. The signal strength profile for the radiative system exhibits an increase in strength at distances less than 20~cm for the shoulder and l~m for the back sensors due to the obstruction of propagation by the body, followed by radiative decay with distance. In contrast, the network based on radio-wave confinement is characterized by an exponential decay away from the body, resulting in about 40 dB lower signal strength at a distance of 2.5 m from the body. This localization of energy near the body provides security at the physical layer of communication that is complementary to approaches based on encryption or protocol. In addition, radio-wave confinement may suppress interference between neighboring networks and eliminate the need for spectrum sharing protocols. Such personal networks immune to interference could enable individual utilization of full radio bands without degradation of performance from nearby devices. 

[0098] Reference is now made to FIG. 4A, which is a schematic illustration of an image of a wrist- worn pulse sensor wirelessly powered by radio-waves guided along a metamaterial textile sleeve. The pulse sensor comprises of an energy harvesting unit, pressure sensor, and LED for visual indication. The pressure sensor is placed under the textile on the wrist. The confinement of radio-waves on metamaterial textiles also enables wireless power transfer to many classes of low-power sensors. As a demonstrative example, a pulse indicator was wirelessly powered on the wrist of a user by guiding energy along a long-sleeved sweater along the length of the user’s arm. 

[0099] Reference is now made to FIG. 4B, which is a schematic illustration of an image of the energy harvesting unit on the metamaterial textile and its circuit schematic. The pressure sensor (not shown) is represented by the variable resistor in the circuit schematic. This sensor device provides a visual 

