Vasconcelos Beatriz, Fiedler Patrique, Machts René, Haueisen Jens, Fonseca Carlos
Departamento de Engenharia Metalúrgica e de Materiais, Faculdade de Engenharia, Universidade do Porto, Porto, Portugal.
CEMUC - Department of Mechanical Engineering, University of Coimbra, Coimbra, Portugal.
Front Neurosci. 2021 Oct 18;15:748100. doi: 10.3389/fnins.2021.748100. eCollection 2021.
Electroencephalography (EEG) is increasingly used for repetitive and prolonged applications like neurofeedback, brain computer interfacing, and long-term intermittent monitoring. Dry-contact electrodes enable rapid self-application. A common drawback of existing dry electrodes is the limited wearing comfort during prolonged application. We propose a novel dry Arch electrode. Five semi-circular arches are arranged parallelly on a common baseplate. The electrode substrate material is a flexible thermoplastic polyurethane (TPU) produced by additive manufacturing. A chemical coating of Silver/Silver-Chloride (Ag/AgCl) is applied by electroless plating using a novel surface functionalization method. Arch electrodes were manufactured and validated in terms of mechanical durability, electrochemical stability, applicability, and signal characteristics. We compare the results of the dry arch electrodes with dry pin-shaped and conventional gel-based electrodes. 21-channel EEG recordings were acquired on 10 male and 5 female volunteers. The tests included resting state EEG, alpha activity, and a visual evoked potential. Wearing comfort was rated by the subjects directly after application, as well as at 30 min and 60 min of wearing. Our results show that the novel plating technique provides a well-adhering electrically conductive and electrochemically stable coating, withstanding repetitive strain and bending tests. The signal quality of the Arch electrodes is comparable to pin-shaped dry electrodes. The average channel reliability of the Arch electrode setup was 91.9 ± 9.5%. No considerable differences in signal characteristics have been observed for the gel-based, dry pin-shaped, and arch-shaped electrodes after the identification and exclusion of bad channels. The comfort was improved in comparison to pin-shaped electrodes and enabled applications of over 60 min duration. Arch electrodes required individual adaptation of the electrodes to the orientation and hairstyle of the volunteers. This initial preparation time of the 21-channel cap increased from an average of 5 min for pin-like electrodes to 15 min for Arch electrodes and 22 min for gel-based electrodes. However, when re-applying the arch electrode cap on the same volunteer, preparation times of pin-shaped and arch-shaped electrodes were comparable. In summary, our results indicate the applicability of the novel Arch electrode and coating for EEG acquisition. The novel electrode enables increased comfort for prolonged dry-contact measurement.
脑电图（EEG）越来越多地用于神经反馈、脑机接口和长期间歇性监测等重复性和长时间的应用中。干接触电极可实现快速自我佩戴。现有干电极的一个常见缺点是长时间佩戴时舒适度有限。我们提出了一种新型的干拱形电极。五个半圆形拱形平行排列在一个公共基板上。电极基材是通过增材制造生产的柔性热塑性聚氨酯（TPU）。采用一种新颖的表面功能化方法，通过化学镀施加银/氯化银（Ag/AgCl）化学涂层。制造了拱形电极，并在机械耐久性、电化学稳定性、适用性和信号特性方面进行了验证。我们将干拱形电极的结果与干针形电极和传统凝胶基电极的结果进行了比较。在10名男性和5名女性志愿者身上进行了21通道脑电图记录。测试包括静息状态脑电图、α活动和视觉诱发电位。佩戴后以及佩戴30分钟和60分钟时，受试者直接对佩戴舒适度进行评分。我们的结果表明，这种新颖的镀膜技术提供了一种附着力良好的导电且电化学稳定的涂层，能够承受重复应变和弯曲测试。拱形电极的信号质量与针形干电极相当。拱形电极设置的平均通道可靠性为91.9±9.5%。在识别和排除不良通道后，未观察到凝胶基、干针形和拱形电极在信号特性方面有显著差异。与针形电极相比，舒适度有所提高，并且能够进行超过60分钟的应用。拱形电极需要根据志愿者的取向和发型对电极进行个性化调整。21通道帽的初始准备时间从针状电极的平均5分钟增加到拱形电极的15分钟和凝胶基电极的22分钟。然而，当在同一名志愿者身上重新佩戴拱形电极帽时，针形和拱形电极的准备时间相当。总之，我们的结果表明新型拱形电极及其涂层适用于脑电图采集。这种新型电极能够提高长时间干接触测量的舒适度。
