Implantable System for Long- and Short-Term Active Charge Balancing in Neural Electrical Stimulation

功能性电刺激是一种允许通过电荷刺激神经的技术。为了避免引起组织损伤和电极腐蚀的电荷积累，特别是在长期治疗期间，电荷平衡已经成为功能性电刺激的组成部分。然而，出于可靠性的原因，目前大多数CE认证的医疗设备都配备了无源电荷平衡系统，尽管它们尺寸大，建立时间长，电荷补偿不受控制。一种有前途的方法，小，快速，良好控制的电荷补偿是主动电荷平衡。当同时执行测量和刺激时，该技术还具有更好的信号质量的优点。在该项目中，将使用主动电荷平衡对电刺激进行基础研究，以降低刺激风险并促进保存慢性试验。我们的目标是开发和评估CMOS集成，高电压兼容的电荷平衡系统，它可以与各种刺激器结合使用。除了对植入式系统的典型要求外，低功耗和低面积的需求，普通应用的多样性需要有源电荷平衡系统在，例如，可配置的安全限制、输出电流限制和自适应电源轨，最高可兼容30 V的高压。为了满足这些要求并实现明确的电荷平衡，将单独或组合考虑和追求用于长期和短期刺激的有源电荷平衡的补充方法。每种方法都表示充分良好地执行的控制回路，同时在彼此组合时提供实现电荷平衡的更好性能的机会。考虑到多电极配置，从而多输入多输出系统，链接控制回路的方法将被考虑和开发，其稳定性，相互作用和性能评估。

Functional electrical stimulation is a technique that allows for the stimulation of nerves by electrical charge. In order to avoid charge accumulation which causes tissue lesion and electrode corrosion, in particular during long-term treatments, charge balancing has become an integral part of functional electrical stimulation. However, for reliability reasons, most CE-certified medical devices are equipped with passive charge balancing systems today, despite their large size, long settling time, and uncontrolled charge compensation. A promising approach to small, fast, and well controlled charge compensation is active charge balancing. This technique also comes up with the advantage of a better signal quality when measurements and stimulations are performed simultaneously. In this project, fundamental research will be performed on electrical stimulation using active charge balancing in order to reduce the risks of stimulation and facilitate save chronic trials. The objective is to develop and evaluate a CMOS integrated, high-voltage compatible charge balancing system, which can be used in combination with a variety of stimulators. In addition to the typical requirements on implantable systems, e.g., low-power consumption and low-area demand, the diversity of common applications necessitates a high adaptability and flexibility of the active charge balancing system in terms of, e.g., configurable safety limits, output current limitation and adaptive supply rails with high-voltage compatibility up to 30V.In order to meet these requirements and to achieve a well-defined charge balancing, the complementary approaches to active charge balancing for long- and short-term stimulation will be considered and pursued, both separately and in combination. Each approach represents a sufficiently well performing control loop while providing the opportunity to achieve a better performance in charge balancing when being combined with each other. Considering multiple-electrode configurations and thus multiple-input multiple-output systems, approaches to linked control loops will be considered and developed and their stability, interaction, and performance evaluated.