School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China.
Innovation Center for Textile Science and Technology, Donghua University, Shanghai, China.
J Neurosci Methods. 2019 Dec 1;328:108450. doi: 10.1016/j.jneumeth.2019.108450. Epub 2019 Sep 29.
Reliable interfacing with peripheral nervous system is essential to extract neural signals. Current implantable peripheral nerve electrodes cannot provide long-term reliable interfaces due to their mechanical mismatch with host nerves. Carbon nanotube (CNT) yarns possess excellent mechanical flexibility and electrical conductivity. It is of great necessity to investigate the selectivity of implantable CNT yarn electrodes.
Neural interfaces were fabricated with CNT yarn electrodes insulated with Parylene-C. Acute recordings were carried out on tibial nerves of rats, and compound nerve action potentials (CNAPs) were electrically evoked by biphasic current stimulation of four toes. Spatiotemporal characteristics of neural activity and spatial selectivity of the electrodes, denoted by selectivity index (SI), were analyzed in detail.
Conduction velocities of sensory afferent fibers recorded by CNT yarn electrodes varied between 4.25 m/s and 37.56 m/s. The SI maxima for specific toes were between 0.55 and 0.99 across seven electrodes. SIs for different CNT yarn electrodes are significantly different among varied toes.
Most single CNT yarn electrode with a ∼ 500 μm exposed length can be sensitive to one or two specific toes in rodent animals. While, it is only possible to discriminate two non-adjacent toes by multisite TIME electrodes.
Single CNT yarn electrode exposed ∼ 500 μm showed SI values for different toes comparable to a multisite TIME electrode, and had high spatial selectivity for one or two specific toes. The electrodes with cross section exposed could intend to be more sensitive to one specific toe.
可靠的外周神经接口对于提取神经信号至关重要。目前的植入式周围神经电极由于与宿主神经的机械失配，无法提供长期可靠的接口。碳纳米管（CNT）纱线具有优异的机械柔韧性和导电性。因此，研究植入式 CNT 纱线电极的选择性具有重要意义。
使用聚对二甲苯-C 绝缘的 CNT 纱线电极制作神经接口。在大鼠的胫神经上进行急性记录，并通过对四个脚趾的双相电流刺激来电诱发复合神经动作电位（CNAPs）。详细分析了神经活动的时空特征和电极的空间选择性，用选择性指数（SI）表示。
由 CNT 纱线电极记录的感觉传入纤维的传导速度在 4.25 m/s 到 37.56 m/s 之间变化。七个电极中特定脚趾的 SI 最大值在 0.55 到 0.99 之间。不同 CNT 纱线电极的 SI 差异显著。
大多数暴露长度约为 500 μm 的单根 CNT 纱线电极可以对啮齿动物的一个或两个特定脚趾敏感。而，通过多点 TIME 电极只能区分两个不相邻的脚趾。
暴露约 500 μm 的单根 CNT 纱线电极对不同脚趾的 SI 值与多点 TIME 电极相当，对一个或两个特定脚趾具有较高的空间选择性。暴露横截面的电极可能对一个特定的脚趾更敏感。
