無線多通道微系統開發應用於可自由活動之大鼠腦神經電訊號感測

Abstract

本論文旨在發展一個整合式無線多通道微系統，可應用於各式腦神經生理電訊號監測。應用無線傳輸技術可讓受測對象有更高的自由度、不受繁雜的線材所限制，微系統的微小化整合設計使其符合高度可攜應用環境之要求，如應用於動物需自由活動條件下的相關實驗等。此微系統設計包括了以Chip-on-Board (COB)方式封裝之低雜訊十六通道類比前端放大電路晶片，與其他元件進行整合而成一個無線多通道微系統。此微系統架構包括(1)低雜訊低功耗之十六通道類比前端晶片(2)數位電路控制系統(3)無線藍牙模組及(4)電腦端軟體。系統中的硬體皆採用表面接著元件(SMD)，利用有效之電路設計與佈線技巧減少面積以達到系統微小化的目的。四層板的設計可以避免系統內類比與數位訊號的相互干擾，降低雜訊對生理訊號的干擾。以大鼠動物實驗為目標之微系統設計分為Headstage及Main board兩部分，前者安裝於大鼠頭部直接連結至植入式電極，後者置於特別設計的背包中讓大鼠背負。整體系統重量不含電池少於13克。特別設計的Headstage機構可降低系統遭撞擊機會，使受測大鼠活動更加自由。透過藍牙無線傳輸介面，可於電腦端軟體上直接下達指令及接收所擷取到的腦神經生理電訊號。本系統可提供低雜訊16通道的訊號量測，每通道具有300Hz(最高1.25K)取樣頻率與12位元解析度。未來可進一步搭配無線傳能技術與各式刺激源設計，發展各式腦神經訊號偵測與抑制之腦機介面。

This thesis aims to develop an integrated wireless multichannel micro-system for various neural monitoring. Application of wireless transmission technology and miniaturized microsystem allow the freedom of moving objects without cables restriction. Presented work realized the integration of a low-noise 16-channel analog-front-end (AFE) chip with other commercial parts i.e. micro controller and RF module by chip-on-board (COB) method in a small-form-factor wireless multi-channel micro-system. Proposed design consists of four main parts: Low-noise low-power 16-channel AFE chip, micro controller, Bluetooth module and laptop software design. Surface mounted devices (SMD) were chosen to reduce circuit size with effective circuit layout techniques. To minimize noise interference of recorded physiological signals, four-layer board design is utilized to avoid noise coupling between analog and digital signals. In animal’s experiments, the system structure is divided into two parts, say Headstage and Main-Board, to meet the setup requirements for rat’s experiments. The Headstage was installed onto rat’s head for direct connection to the implanted electrodes, the Main-board is carried in a specially designed backpack on rat’s back. The overall system weights less than 13g without battery and is capable of simultaneous recording 16-channel signal at 300(max 1.25K)Hz sample rate and 12-bit resolution. Further works may include the wireless powering module and various stimulation’s design to realize a complete brain-computer interface.