IEEE Trans Biomed Circuits Syst. 2018 Dec;12(6):1279-1288. doi: 10.1109/TBCAS.2018.2866960.
The intraoral Tongue Drive System (iTDS) is a wireless assistive technology that detects users' voluntary tongue gestures, and converts them to user-defined commands, enabling them to access computers and navigate powered wheelchairs. In this paper, we presented a transmitter (Tx) with adaptive matching and three bands (27, 433, and 915 MHz) to create a robust wireless link between iTDS and an external receiver (Rx) by addressing the effects of external RF interference and impedance variations of the Tx antenna in the dynamic mouth environment. The upper two Tx bands share a dual-band antenna, while the lower band drives a coil. The Tx antenna is simulated in a simplified human mouth model in HFSS as well as a real human head model. The adaptive triple-band Tx chip was fabricated in a 0.35-μm 4P2M standard CMOS process. The Tx chip and antenna have been characterized in a human subject as part of an iTDS prototype under open-and closed-mouth scenarios, which present the peak gain of -24.4 and -15.63 dBi at 433 and 915 MHz, respectively. Two adaptive matching networks for these bands compensate variations of the Tx antenna impedance via a feedback mechanism. The measured S tuning range of the proposed network can cover up to 60 and 75 jΩ at 433 and 915 MHz, respectively.
口腔内舌头驱动系统 (iTDS) 是一种无线辅助技术，可检测用户的自愿舌运动，并将其转换为用户定义的命令，使他们能够访问计算机和控制动力轮椅。在本文中，我们提出了一种具有自适应匹配和三个频段（27、433 和 915 MHz）的发射器 (Tx)，通过解决外部射频干扰的影响和 Tx 天线在动态口腔环境中的阻抗变化，在 iTDS 和外部接收器 (Rx) 之间创建了一个强大的无线链路。上两个 Tx 频段共享一个双频天线，而下频段则驱动一个线圈。Tx 天线在 HFSS 中的简化人体口腔模型以及真实的人体头部模型中进行了模拟。自适应三频 Tx 芯片采用 0.35-μm 4P2M 标准 CMOS 工艺制造。Tx 芯片和天线已在人体受试者中进行了表征，作为 iTDS 原型的一部分，在开/闭口情况下进行了测试，在 433 和 915 MHz 下的峰值增益分别为-24.4 和-15.63 dBi。这两个频段的两个自适应匹配网络通过反馈机制补偿 Tx 天线阻抗的变化。所提出的网络的 S 调谐范围可分别在 433 和 915 MHz 下覆盖高达 60 和 75 jΩ。
