神經信號無線紀錄系統之初步研究

Abstract

電生理實驗記錄應用於連續觀察清醒自由活動之動物，一般相信可以得到更接近實際腦功能的整合性資料，提供神經科學研究更多元的探討，為了達成此目標，無線記錄系統無疑是發展趨勢，但目前市面上成熟之無線技術如FM、Zigbee與Bluetooth對於神經信號記錄之傳輸各有其發展限制，因此在高傳輸率和省電的前提下，希望能開發新的無線記錄系統以記錄神經群的活動。 本研究基於神經信號多通道連續記錄的高資料量，初步評估與發展一無線記錄系統。系統共分為兩部分，前端發射模組主要以省電為最大考量，結合了放大濾波、類比/數位轉換及高傳輸率發射器，後端接收則針對此發射器建立了高資料頻寬接收模組，除了使用類比解調變元件之外，透過數位解調變方式減少元件複雜度，以處理發射接收兩端載波和時序不同步之問題，加速初期開發。最後藉由USB傳輸儲存資料於電腦中，並將取樣數位化後的神經訊號轉換回波形。 根據實際動物實驗所獲得結果，此無線記錄系統對單通道觸覺誘發之複合神經動作電位資料以3 Mbps高傳輸率所得之波形與有線傳輸的波形相似度達98.86%，同時前端發射模組整體耗電量為12 mA。期望透過本初期研究，能對下階段多通道無線記錄有所助益。

It is known that the result of electrophysiology experiment reveals more realistic and integrated information while animals under testing are awake treated and freely moving. For this reason, wireless recording is an inexorable trend. However, well-developed wireless techniques such as FM, Zigbee, Bluetooth, etc. impose different limitation on the recording of neuronal signals. This thesis is a pilot research of wireless recoding system based on the concept that high data rate is necessary for continuously multichannel recording of neuronal signals. There are a transmitter module and a receiver module in this system. Since the most critical issues of the front-end transmitter module are low power consumption and as small as possible, low power amplifiers, filters and a high data rate transmitter are implemented in this study. A receiver module is build specifically for the high data rate transmitter. It contains the analog demodulation circuit, digital demodulation and the acquisition of data via USB. To deal with the non-synchronization problem of carrier and timing between transmitter and receiver ends, digital demodulation is done by computer program. In addition, a software user interface is programmed with C++ language to control the receiver module. A single channel compound action potentials is used for examination of the developed system, and we transmits 100 kHz sampled data at 3 Mbps while consuming 12 mA in total. Compared to the wired measurement, reconstructed wave with wireless transmission are 98.86% similar. Notwithstanding, this preliminary study provides a basis for further multichannel recoding.