應用於抑制癲癇發作之雙模式刺激器系統設計

Abstract

癲癇是一種神經系統疾病，通常是腦病變造成的腦細胞突然異常的過度放電。這種狀況進而引發其他部位的異常放電，而產生癲癇發作。而世界上約有1%的人口(六千五百萬人)患有癲癇，近80％的病例都發生在發展中國家，且發病率隨年齡增長而增高。 隨著科技演進，功能性電刺激技術已廣泛用於醫療用途。功能性電刺激（Functional Electrical Stimulation）指利用一定強度的電流，藉由刺激脈波來刺激神經或者肌肉，誘發肌肉運動或模擬正常的自主運動。功能性電刺激協助患者的肢體動作功能可以重建，而使患者回復正常肢體功能。 目前大部分功能性電刺激的方式都是利用定電流刺激，而在本篇論文則提出雙模式刺激的方式，也就是使用定電壓與定電流刺激。此刺激器晶片在電流模式能輸出0.1mA~5mA，在電壓模式則可以輸出0.5V~10V的刺激大小。此外，因為電極以及人體組織阻抗會隨著電極擺放位置以及電極的大小而有所不同，加上考慮刺激規格所需的電流與電壓，因此刺激器系統還整合了電荷幫浦電路，能將5V輸入電壓升壓至18V輸出電壓供給刺激器系統做使用。 目前市面上的功能性電刺激器儀器都具有雙模式刺激的功能，將這些儀器晶片化將帶有體積與成本方面的優勢。並且，對於不同的病理需求如:癲癇抑制、人工電子耳、帕金森氏症，運用不同的刺激方式可以達成不同治療效果，可藉此探討每種症狀較佳的刺激模式與方式。

Epilepsy is a neurological disease, usually caused by cells of brain abnormally excessive discharge. This situation will lead abnormal discharge of other parts, and induce seizures. About 1% of the population (six thousand and five hundred million) in the world suffer from epilepsy, nearly 80% of cases occur in developing countries, and the incidence increased with age. With the evolution of technology, functional electrical stimulation technology has been widely used for medical purposes. Functional electrical stimulation refers to using of certain current amplitude and use pulse to stimulate nerves or muscles, it can induce muscle movement or simulate normal voluntary movement. Functional electrical stimulation helps the motor function of patients can be rebuilt and the patients can return to normal limb function. At present, most of functional electrical stimulation are using constant current stimulation method, and in this thesis has proposed the dual mode stimulation method, that is, using of constant voltage and constant current stimulation. This stimulator chip can output 0.1mA ~ 5mA in current mode, and generate 0.5V ~ 10V in voltage mode. In addition, the impedance of electrode and tissue as the electrode size and placement of the electrodes varies, with consideration of the current or voltage required to meet the stimulation specifications, thus stimulator system also integrate the charge pump circuit which is capable of boosting the input voltage 5V to 18V output voltage to supply the whole stimulator system. Most functional electrical stimulation instrument currently on the market have a dual-mode function, and to wafer these instruments will advantage of volume and cost. Besides, for different pathological needs such as: epilepsy suppression, cochlear implants, Parkinson's disease, using of different stimulation method can achieve different treatment effects, and investigate each symptom preferred stimulus patterns and methods.