Passive Impedance Matching for Implanted Brain-Electrode Interfaces
Passive Impedance Matching for Implanted Brain-Electrode Interfaces
复制标题
DOI：
10.1109/jerm.2019.2904024
复制
发表时间：
2019-12-01
影响因子：
3.2
通讯作者：
Kiourti, Asimina
中科院分区：
文献类型：
--
作者：
Chen, Wei-Chuan;Guido, Katrina;Kiourti, Asimina
我们提出了一种新的技术，用于匹配的高阻抗的颅内电极的无线脑植入物，是被动的，高度容忍的直流偏移电压所造成的电化学反应在记录电极，并辅以改进的外部可编程逻辑器件的设计，表现出降低相位噪声。与以前的无线和无电池的大脑植入物相比，所提出的方法在灵敏度上显著提高了25倍。该系统包括一个外部的头皮和植入头皮下的神经记录仪。为了操作，植入器发送2.4 GHz载波信号以打开植入物。该载体自偏置PNP双极结型晶体管（BJT），其能够以无电池的方式在频率f（neuro）下与记录电极匹配。同时，记录的神经电位（频率为f（neuro））通过肖特基二极管，使其与载波混合并产生4.8 GHz +/- f（neuro）调制信号。然后将后者发送回解调器进行解调。为了验证植入物的操作，提出了体外测量。测量结果表明，仿真的神经电位低至200 μ V-PP可以检测到在33-K Ω电极阻抗。因此，所提出的系统为广泛的应用提供了改变游戏规则的能力。
We propose a new technique for matching the high impedance of sub-cranial electrodes to wireless brain implants that is passive, highly tolerant of the dc offset voltage caused by the electrochemical reaction in the recording electrode, and complemented by an improved external interrogator design that exhibits reduced phase noise. As compared to previouswireless and batteryless brain implants, the proposed approach offers a remarkable improvement in sensitivity by 25 times. The proposed system consists of an external interrogator and a neuro-recorder implanted under the scalp. For operation, the interrogator sends a 2.4-GHz carrier signal to turn on the implant. This carrier self-biases a PNP Bipolar Junction Transistor (BJT) that enables matching to the recording electrode at frequency f(neuro) in a batteryless manner. Concurrently, the recorded neuropotentials (at frequency f(neuro)) pass through a Schottky diode that allows them to mix with the carrier and generate a 4.8 GHz +/- f(neuro) modulated signal. The latter is then transmitted back to the interrogator for demodulation. To verify the implant's operation, in-vitro measurements are presented. Measurement results demonstrate that emulated neuropotentials as low as 200 mu V-pp can be detected at a 33-k Omega electrode impedance. As such, the proposed system presents a game-changing capability for a wide range of applications.