Department of Electronic, Electrical and Systems Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
School of Mechanical, Materials, Mechatronic, and Biomedical Engineering, University of Wollongong, Wollongong, Australia.
Biosens Bioelectron. 2023 Sep 1;235:115414. doi: 10.1016/j.bios.2023.115414. Epub 2023 May 20.
Biopotential signals, like electrocardiography (ECG), electromyography (EMG), and electroencephalography (EEG), can help diagnose cardiological, musculoskeletal and neurological disorders. Dry silver/silver chloride (Ag/AgCl) electrodes are commonly used to obtain these signals. While a conductive hydrogel can be added to Ag/AgCl electrodes to improve the contact and adhesion between the electrode and the skin, dry electrodes are prone to movement. Considering that the conductive hydrogel dries over time, the use of these electrodes often creates an imbalanced skin-electrode impedance and a number of sensing issues in the front-end analogue circuit. This issue can be extended to several other electrode types that are commonly in use, in particular, for applications with a need for long-term wearable monitoring such as ambulatory epilepsy monitoring. Liquid metal alloys, such as eutectic gallium indium (EGaIn), can address key critical requirements around consistency and reliability but present challenges on low viscosity and the risk of leakage. To solve these problems, here, we demonstrate the use of a non-eutectic Ga-In alloy as a shear-thinning non-Newtonian fluid to offer superior performance to commercial hydrogel electrodes, dry electrodes, and conventional liquid metals for electrography measurements. This material has high viscosity when still and can flow like a liquid metal when sheared, preventing leakage while allowing the effective fabrication of electrodes. Moreover, the Ga-In alloy not only has good biocompatibility but also offers an outstanding skin-electrode interface, allowing for the long-term acquisition of high-quality biosignals. The presented Ga-In alloy is a superior alternative to conventional electrode materials for real-world electrography or bioimpedance measurement.
生物电位信号，如心电图（ECG）、肌电图（EMG）和脑电图（EEG），可帮助诊断心脏、肌肉骨骼和神经系统疾病。通常使用干银/氯化银（Ag/AgCl）电极来获取这些信号。虽然可以在 Ag/AgCl 电极上添加导电水凝胶以改善电极与皮肤之间的接触和附着力，但干电极容易移动。考虑到导电水凝胶会随着时间的推移而干燥，因此这些电极的使用通常会导致电极和皮肤之间的阻抗不平衡，并在前端模拟电路中产生一系列传感问题。这个问题可以扩展到其他几种常用的电极类型，特别是对于需要长期可穿戴监测的应用，如动态癫痫监测。镓铟共晶（EGaIn）等液态金属合金可以满足一致性和可靠性等关键关键要求，但在低粘度和泄漏风险方面存在挑战。为了解决这些问题，在这里，我们展示了使用非共晶 Ga-In 合金作为剪切稀化非牛顿流体，为电描记术测量提供优于商业水凝胶电极、干电极和传统液态金属的性能。这种材料静止时具有高粘度，剪切时可像液态金属一样流动，防止泄漏的同时允许有效制造电极。此外，Ga-In 合金不仅具有良好的生物相容性，而且还提供了出色的皮肤电极界面，允许长期获取高质量的生物信号。所提出的 Ga-In 合金是传统电极材料的优越替代品，可用于实际的电描记术或生物阻抗测量。
