具有正負電壓極性之抑制癲癇發作雙向電流刺激器設計

Abstract

近年，結合醫學與微電子學，電流刺激器已被視為嶄新的醫療技術，治療性電刺激已被證實可以藉由傳送電訊號給神經系統來恢復人體的某些身理功能。在輸出雙向刺激電流時，隨著不同電極組織的等效阻抗，在輸出端可能有接近七伏特的高壓，為了承受輸出端的高壓，過去的刺激器電路大多使用高壓製程來實作，而本刺激器電路為了與智慧型仿生系統中的其他電路做單晶片整合，因此必須使用低壓製程來實作。本刺激器透過堆疊電晶體和電壓限制的技巧，使其能以低壓製1.8V/3.3V元件來承受正負高工作電壓(±7.2V)，而電晶體不會面臨電性過壓的可靠度題。並且，晶片外部只提供1.8V，需要由晶片內部的電荷幫浦(charge pump)電路 提供給驅動(driver)電路所需的正負工作電壓，整個刺激器須考慮到電路可靠度、功率消耗、輸出電壓範圍等。

In this work, a high-voltage-tolerant stimulator in a 0.18μm 1.8V/3.3V CMOS process is proposed. Using stacked transistors and voltage limiting technique prevent from reliability issues such as electrical overstress and gate-oxide breakdown. The stimulus driver is designed to deliver charge balanced biphasic pulses and reduces the mismatch between the anodic and cathodic pulses to avoid charge accumulation hurting the never cells. The proposed monopolar biphasic stimulator consists of the stimulus driver, positive high voltage generator, and negative high voltage generator. The loading of stimulator can be adaptive within the electrode-tissue impedance from 50kΩ to 200kΩ in series with capacitor of 12nF ~ 200nF in stimulus current of 30 μA.