Chronic softening spinal cord stimulation arrays
Chronic softening spinal cord stimulation arrays
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DOI：
10.1088/1741-2552/aab90d
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发表时间：
2018-08-01
影响因子：
4
通讯作者：
Voit, Walter
中科院分区：
文献类型：
--
作者：
Garcia-Sandoval, Aldo;Pal, Ajay;Voit, Walter
客观的。我们试图为大鼠开发一种耐用、稳定且不会干扰底层脊髓的颈脊髓刺激器。方法。我们创建了一种由基于形状记忆聚合物 (SMP) 的柔性电子器件制成的软化脊髓刺激 (SCS) 阵列。我们开发了一种新的光刻工艺，可将高表面积氮化钛 (TiN) 电极图案化到金 (Au) 互连件上。硫醇-烯丙烯酸酯聚合物在室温下是硬的，并在植入体内后软化。耐用性是通过设备产生有效刺激的持续时间和体外加速老化来衡量的。通过引发肌电图 (EMG) 肌肉反应的阈值以及使用电化学阻抗谱 (EIS) 测量阻抗来测量稳定性。此外，还测量了运动皮层电位的脊髓调节。使用 MRI 离体对脊柱和植入阵列进行成像，并进行星形胶质细胞增生和免疫反应的组织学检查。主要结果。为了保证耐用性，阵列的设计经过了三代的修改，以创建出可展示长达 29 周活性的阵列。在模拟的 29 周加速老化期间，SCS 阵列没有表现出明显的退化。为了稳定性，引发 EMG 的阈值在最初几周内上升，然后保持稳定到 16 周；阻抗在早期表现出类似的上升，随后保持稳定。脊髓刺激强烈增强了整个运动皮层的电位。移植后，设备性能恢复到植入前的水平，表明生物过程而不是非生物过程是导致指标变化的原因。 MRI 和组织学表明，软化的 SCS 产生的组织变形比 Parrene-C 阵列要少。两种类型的阵列均未出现明显的星形胶质细胞增生或免疫反应。意义。软化 SCS 阵列满足了大鼠研究级设备的需求，并且将来可以开发为人体设备。
Objective. We sought to develop a cervical spinal cord stimulator for the rat that is durable, stable, and does not perturb the underlying spinal cord. Approach. We created a softening spinal cord stimulation (SCS) array made from shape memory polymer (SMP)-based flexible electronics. We developed a new photolithographic process to pattern high surface area titanium nitride (TiN) electrodes onto gold (Au) interconnects. The thiol-ene acrylate polymers are stiff at room temperature and soften following implantation into the body. Durability was measured by the duration the devices produced effective stimulation and by accelerated aging in vitro. Stability was measured by the threshold to provoke an electromyogram (EMG) muscle response and by measuring impedance using electrochemical impedance spectroscopy (EIS). In addition, spinal cord modulation of motor cortex potentials was measured. The spinal column and implanted arrays were imaged with MRI ex vivo, and histology for astrogliosis and immune reaction was performed. Main results. For durability, the design of the arrays was modified over three generations to create an array that demonstrated activity up to 29 weeks. SCS arrays showed no significant degradation over a simulated 29 week period of accelerated aging. For stability, the threshold for provoking an EMG rose in the first few weeks and then remained stable out to 16 weeks; the impedance showed a similar rise early with stability thereafter. Spinal cord stimulation strongly enhanced motor cortex potentials throughout. Upon explantation, device performance returned to pre-implant levels, indicating that biotic rather than abiotic processes were the cause of changing metrics. MRI and histology showed that softening SCS produced less tissue deformation than Parylene-C arrays. There was no significant astrogliosis or immune reaction to either type of array. Significance. Softening SCS arrays meet the needs for research-grade devices in rats and could be developed into human devices in the future.