應用於大腦皮質波量測之十六通道生理電極

Abstract

本論文研究利用微機電技術（Micro-Electro-Mechanical Systems, MEMS）製作生理訊號電極量測老鼠之大腦皮質波（Electrocorticography, ECoG），利用聲音的刺激引發老鼠大腦內神經的電訊號，藉由新型生理電極偵測微弱的訊號，經由後端放大取樣系統運算可以得到十八組不同位置的腦細胞訊號，其中取一點定義為地線和另一點做為參考點，經過一百次的平均後可用於分析十六個不同腦區產生訊號的時間解析度(Temporal Resolution)與空間解析度(Spatial Resolution)之間關係。 生理電極使用兩層聚對二甲苯（10um, 1um）包覆白金（Pt）走線，利用氧氣電漿(O2 Plasma)轟擊來定義出電極開孔與電極外型，穩定且批次(Batch)的生產電極，經過封裝後完成生理電極的製作。生理電極的設計針對老鼠頭部形狀，將電極完全植入體內，利用特殊的接頭將腦神經訊號傳遞至後端系統，成功的在手術完後紀錄聲音刺激訊號（Auditory Evoked Potentials, AEP）。 分析生理電極紀錄的訊號可以初步的判斷老鼠主要的聽覺區和鄰近的聽覺區關係，高頻的分析（Gamma Band）則可以找出聽覺神經的連結和區域功能，未來可以應用在癲癇(Epilepsy)的偵測、或是紀錄電刺激(Electrical Stimulation)的反應、甚至結合微流道(Micro-fluidic Channel)進行藥物的注射。

This research utilizes Micro-Electro-Mechanical-System(MEMS) technology process to develop bio-electrode to measure Sprague Dawley(SD) rat’s Electrocorticography(ECoG) signal. The electrical signal in rat’s brain is evoked by auditory stimulation and can be detected with the new developed bio-electrode sensor. And then the back-end system will record signals from eighteen positions. We choose two signals as the ground signal and reference signal, respectively. After one hundred times average, we can analyze the relationship between temporal resolution and spatial resolution of sixteen positions of brain. The Bio-electrode is fabricated with two parylene layers (10um, 1um) to cover the platinum metal wires. Oxygen Plasma is used to etch electrode’s size and define the shape of Bio-electrode. After process, we can stably batch production of electrode device. In order to implant into rat’s body, the Bio-electrode is designed to fit the curvature of SD rat’s head bone. Besides, we use a special connector to transmit signal to back-end system and successfully record Auditory Evoked Potentials (AEP) signal after implant surgery. Analyzing the ECoG electrode data can preliminarily distinguish the relationship from the main and neighbor auditory response area. Furthermore, high frequency analyzing (Gamma Band) can identify the nerve’s connection and function of brain region. In the future, we will apply our Bio-electrode in Epilepsy detection or Electrical Stimulation, and even combining with Micro-fluidic Channel to execute medicine injection.