Safe direct current stimulation to expand capabilities of neural prostheses.
Safe direct current stimulation to expand capabilities of neural prostheses.
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DOI：
10.1109/tnsre.2013.2245423
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发表时间：
2013-03
期刊：
影响因子：
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通讯作者：
Della Santina CC
中科院分区：
文献类型：
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作者：
Fridman GY;Della Santina CC
虽然在治疗某些神经系统疾病方面有效，但神经电假体从根本上受到限制，因为它们必须采用电荷平衡刺激以避免在金属电极和体液之间的界面处发生不可逆电化学反应及其副产物。电荷平衡通常通过使用短暂的双相交流（AC）脉冲来实现，其通常激发附近的神经组织但不能有效地抑制它们。相比之下，通过与体液接触的金属电极施加的直流电（DC）可以激发、抑制和调节神经元的敏感性;然而，DC刺激在生物学上是不安全的，因为它违反了长期以来被认为是不可避免的约束的“安全电荷注入”限制。在这份报告中，我们描述了一个安全的直流刺激器（SDCS），克服了这一限制的设计和制造。SCDS通过盐桥微量移液器电极驱动DC离子电流进入靶组织，方法是通过与施加到器械内金属电极的AC方波同相切换阀门。该方法实现了通过组织的DC离子流，同时仍然遵守每个电极-盐水界面处的电荷平衡约束。我们显示了SDCS的能力，抑制和兴奋的神经活动，以实现改善的动态范围在龙猫的内耳前庭部分的假体刺激。
While effective in treating some neurological disorders, neuroelectric prostheses are fundamentally limited because they must employ charge-balanced stimuli to avoid evolution of irreversible electrochemical reactions and their byproducts at the interface between metal electrodes and body fluids. Charge-balancing is typically achieved by using brief biphasic alternating current (AC) pulses, which typically excite nearby neural tissues but cannot efficiently inhibit them. In contrast, direct current (DC) applied via a metal electrode in contact with body fluids can excite, inhibit and modulate sensitivity of neurons; however, DC stimulation is biologically unsafe because it violates “safe charge injection” limits that have long been considered unavoidable constraints. In this report, we describe the design and fabrication of a safe DC stimulator (SDCS) that overcomes this constraint. The SCDS drives DC ionic current into target tissue via salt-bridge micropipette electrodes by switching valves in phase with AC square waves applied to metal electrodes contained within the device. This approach achieves DC ionic flow through tissue while still adhering to charge-balancing constraints at each electrode-saline interface. We show the SDCS’s ability to both inhibit and excite neural activity to achieve improved dynamic range during prosthetic stimulation of the vestibular part of the inner ear in chinchillas.