John A. Paulson School of Engineering and Applied Sciences, Harvard University, 150 Western Avenue, Boston, MA, 02134, USA.
Adv Healthc Mater. 2023 Jul;12(17):e2202661. doi: 10.1002/adhm.202202661. Epub 2023 Mar 30.
Cutaneous electrodes are routinely used for noninvasive electrophysiological sensing of signals from the brain, the heart, and the neuromuscular system. These bioelectronic signals propagate as ionic charge from their sources to the skin-electrode interface where they are then sensed as electronic charge by the instrumentation. However, these signals suffer from low signal-to-noise ratio arising from the high impedance at the tissue-to-electrode contact interface. This paper reports that soft conductive polymer hydrogels made purely of poly(3,4-ethylenedioxy-thiophene) doped with poly(styrene sulfonate) present nearly an order of magnitude decrease in the skin-electrode contact impedance (88%, 82%, and 77% at 10, 100, and 1 kHz, respectively) when compared to clinical electrodes in an ex vivo model that isolates the bioelectrochemical features of a single skin-electrode contact. Integrating these pure soft conductive polymer blocks into an adhesive wearable sensor enables high fidelity bioelectronic signals with higher signal-to-noise ratio (average 2.1 dB increase, max 3.4 dB increase) when compared to clinical electrodes across all subjects. The utility of these electrodes is demonstrated in a neural interface application. The conductive polymer hydrogels enable electromyogram-based velocity control of a robotic arm to complete a pick and place task. This work provides a basis for the characterization and use of conductive polymer hydrogels to better couple human and machine.
皮肤电极通常用于无创式电生理感应来自大脑、心脏和神经肌肉系统的信号。这些生物电子信号通过离子电荷从其源传播到皮肤-电极界面，然后被仪器感测为电子电荷。然而，这些信号的信噪比很低，这是由于组织-电极接触界面的高阻抗引起的。本文报道了由纯聚(3,4-乙撑二氧噻吩)掺杂聚(苯乙烯磺酸盐)制成的柔软导电聚合物水凝胶，与在离体模型中隔离单个皮肤-电极接触的生物电化学特性的临床电极相比，在 10、100 和 1 kHz 时，皮肤-电极接触阻抗分别降低了近一个数量级（88%、82%和 77%）。将这些纯软导电聚合物块集成到粘性可穿戴传感器中，与临床电极相比，可实现更高信噪比的高保真生物电子信号（所有受试者的平均增加 2.1 dB，最大增加 3.4 dB）。这些电极在神经接口应用中得到了验证。导电聚合物水凝胶可实现基于肌电图的机器人手臂速度控制，以完成拾取和放置任务。这项工作为导电聚合物水凝胶的特性描述和使用提供了基础，以更好地实现人机结合。
