Antennas for Intraoral Tongue Drive System at 2.4 GHz: Design, Characterization, and Comparison

The intraoral Tongue Drive System (iTDS), is a tongue-controlled wireless assistive technology, operated by a number of user-defined voluntary tongue gestures to issue control commands. In this paper, we present a new arch-shaped iTDS, occupying the buccal shelf space in the mouth, without limiting the available space for tongue motions. We describe the design, characterization, and comparison between three types of 2.4-GHz antennas for this system: patch, dipole, and planar inverted-F in terms of gain, directivity, bandwidth, and data communication performance to achieve a robust RF link despite mouth motions. The antennas are designed and simulated in a simple human mouth model and measured in the mouth. Based on simulation and measurement results, using an iTDS prototype made of commercial-off-the-shelf components, the patch antenna has the highest gain in both closed- and open-mouth states, at -10.6 and -9 dBi, respectively. We also measured the propagation loss between the iTDS intraoral antenna and out-of-mouth receiver (Rx) in a real user-case scenario and evaluated the link quality by measuring the packet error rate between the transmitter and RX. The presented antennas have larger bandwidth, smaller area, and higher gain compared to prior work on implantable antennas in the literature, resulting in a robust wireless link for the iTDS application.