Miniaturized Dual Band Antennas for Intra-Oral Tongue Drive System in the ISM Bands 433 MHz and 915 MHz: Design, Safety, and Link Budget Considerations

An intraoral tongue drive system (iTDS) is an assistive technology that enables paralyzed people to improve their lifestyle by allowing them to navigate their wheelchairs and access computers using tongue gestures. In this paper, we present two dual-band antennas: a meandered dipole antenna and a meandered planar inverted-F antenna (PIFA). We designed the proposed antennas to operate at industrial, scientific, and medical (ISM) bands 433 and 915 MHz to mitigate the external interference issue, which can severely affect frequency bands. Our proposed antenna footprints are 17.25 × 8 × 0.635 mm3and 42 × 10 × 0.635 mm3for the PIFA and dipole antenna, respectively. Initially, we designed and analyzed the proposed antennas in multilayer mouth models. The performances of the antennas were validated in a realistic human head phantom. We analyzed the performances of the antennas in terms of the reflection coefficient, gain, efficiency, bandwidth, and link budget for wireless communication in four scenarios. Additionally, to address safety concerns, we calculated the specific absorption rates (SARs) for both antennas and found them to be safe according to the IEEE C95.1.2005 guideline. Finally, we measured the reflection coefficient in the more realistic environment of a 26 year-old subject's mouth. The radiation pattern was measured in a 3-D head model and minced pork muscle, which approximated the open and closed mouth scenarios, respectively. The measurement results were in reasonable agreement with the simulation results.