Department of Electrical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
The David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Sci Rep. 2017 Apr 27;7:46745. doi: 10.1038/srep46745.
Electronic devices placed in the gastrointestinal (GI) tract for prolonged periods have the potential to transform clinical evaluation and treatment. One challenge to the deployment of such gastroresident electronics is the difficulty in powering millimeter-sized electronics devices without using batteries, which compromise biocompatibility and long-term residence. We examined the feasibility of leveraging mid-field wireless powering to transfer power from outside of the body to electronics at various locations along the GI tract. Using simulations and ex vivo measurements, we designed mid-field antennas capable of operating efficiently in tissue at 1.2 GHz. These antennas were then characterized in vivo in five anesthetized pigs, by placing one antenna outside the body, and the other antenna inside the body endoscopically, at the esophagus, stomach, and colon. Across the animals tested, mean transmission efficiencies of -41.2, -36.1, and -34.6 dB were achieved in vivo while coupling power from outside the body to the esophagus, stomach, and colon, respectively. This corresponds to power levels of 37.5 μW, 123 μW and 173 μW received by antennas in the respective locations, while keeping radiation exposure levels below safety thresholds. These power levels are sufficient to wirelessly power a range of medical devices from outside of the body.
电子设备在胃肠道（GI）内长时间放置，有可能改变临床评估和治疗方式。将此类胃肠驻留电子设备投入应用的一个挑战是，难以在不使用电池的情况下为毫米级电子设备供电，因为电池会影响生物兼容性和长期驻留性。我们研究了利用中场无线供电技术，将能量从身体外部传输到胃肠道内各个位置的电子设备的可行性。我们通过仿真和离体测量设计了能够在 1.2GHz 组织中高效运行的中场天线。然后，我们在五头麻醉猪体内对这些天线进行了表征，将一个天线放在体外，另一个天线通过内窥镜放在食管、胃和结肠内。在测试的动物中，从体外到食管、胃和结肠耦合的平均传输效率分别为-41.2、-36.1 和-34.6dB，这相当于在相应位置接收的天线的功率水平分别为 37.5μW、123μW 和 173μW，同时保持辐射暴露水平低于安全阈值。这些功率水平足以从身体外部为各种医疗设备提供无线供电。
