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Description
Smart insoles with integrated 2.45 GHz wireless communication are emerging as a promising technology for gait analysis, injury prevention, and health monitoring. However, the state-of-the-art antennas currently used in the market of smart insoles are usually conventional, and not fine-tuned for this specific application. This is further aggravated by the non-deterministic nature of the wave propagation medium, depolarization issues, mechanical robustness, and so on. This requires transmitting at elevated power levels to ensure a reliable communication link, which leads to increased exposure of the used. One of the approaches to reduce user exposure is to design specifically tuned and impedance-robust antennas. From the impedance robustness perspective, the proximity of the ground has to be taken into account. Moreover, the insole-integrated antenna has to remain flexible and robust to mechanical stress, especially for high-performance athletic applications. Several fundamental antenna types can satisfy these criteria, namely a patch, a loop, a PIFA, and a dipole. In this context, the interaction between these antenna types and the human body must be studied to address concerns regarding the absorption of electromagnetic waves. This study investigates the Specific Absorption Rate (SAR) of a dipole, patch, loop, and PIFA antennas tuned to 2.4-GHz BLE (Bluetooth Low-Energy) bands, embedded in smart insoles that take into account foot anatomy, shoe materials, and soil. Using numerical simulations, we analyze the SAR distribution within the foot tissue and evaluate compliance with international safety standards. The results provide key insights for safe wireless smart insole design.
