微機電技術應用於倒鉤狀乾式腦電波電極之研製

Development of Barbed Dry EEG Electrodes Using MEMS Technology

郭哲希(Che-Hsi Kuo)

指導教授 ： 楊燿州

國立臺灣大學/工學院/機械工程學研究所/碩士(2012年)

https://doi.org/10.6342/NTU.2012.02479

摘要

本研究設計並製作具有倒鉤狀探針的乾式電極，以用於生理電訊號如腦電波之擷取。與傳統濕式電極相較，乾式電極的主要優點是不需導電凝膠之使用，所以不會因導電凝膠逐漸乾燥而使量測訊號品質隨著時間降低，較利於進行長時間量測。為了使本研究開發之探針狀電極可直接刺穿角質層以降低皮膚角質所造成的高阻抗，並避免電極刺及皮膚的真皮層造成使用者感受到疼痛不適，本研究探針之設計的電極探針長度設計於50~100μm之間，以符合人體角質層厚度約10~15μm，表皮層厚度約50~100μm的條件。由於是倒鉤的幾何形狀，電極刺入皮膚後，移除電極所需的力量會增加，可加強電極的附著能力及量測時的穩定性。電極之製作皆以濕蝕刻技術為主，其優點為製作方法簡單、設備需求及製程成本低。我們也利用蝕刻模擬軟體Etch3DTM進行蝕刻模擬，協助濕蝕刻製程之參數規劃。製作過程首先以添加異丙醇之氫氧化鉀蝕刻液製做出探針狀電極，探針平均長度為81μm。初步電極完成之後，則利用光阻旋轉塗佈與對位黃光微影技術，將蝕刻遮罩成功製作於電極之上。本研究使用之蝕刻遮罩材料為負光阻SU-8 2050，其材料優點為可抵抗化學蝕刻並能夠容易定義遮罩形狀。光阻保護遮罩有方形與蝕刻孔式兩種設計。完成後的方形遮罩，其邊長約150μm，高度約120μm。蝕刻孔式遮罩則為利用半徑65μm的半圓形孔洞做為蝕刻孔，其餘部分皆受光阻保護。遮罩完成後，將硝酸與氫氟酸混和做為等向性蝕刻溶液，進行探針倒鉤狀蝕刻成型。利用方形遮罩所完成的倒鉤探針電極，其長度85μm，寬度最寬處21μm，最窄處11μm；蝕刻孔式遮罩完成的探針，長度81μm，寬度最寬處20μm，最窄處12μm。

關鍵字

腦電波 ； 倒鉤狀 ； 乾式電極 ； 濕蝕刻 ； 微機電技術

並列摘要

In this work, barbed dry electrodes are designed and fabricated by MEMS technology for biopotential measurement such as EEG.　Compared to the traditional wet electrodes, the dry electrodes do not need electrolytic gel to reduce the impedance between skin and electrodes, so dry electrodes are more suitable for long-term measurement. Our proposed dry electrodes consist of arrays of miniaturized spikes. These spikes are designed for penetrating human skin so that the high impedance problems associated with layers of the outer skin can be resolved. We design the electrodes 50-100μm in length to avoid the painful or uncomfortable feeling during the measurement. The fabrication of electrodes is based on wet etching, which is simple and low cost. The simulation software Etch3DTM is used to evaluate the fabrication parameters of the wet etching. The spikes are fabricated by KOH. Subsequently, the photoresist is patterned as the etching mask on the spikes, and then etched in the solution mixed with HNO3 and HF. The fabricated barbed electrodes are 81μm in length, and widest and narrowest width is 20μm and 12μm, respectively.

並列關鍵字

EEG ； barbed ； dry electrode ； wet etching ； MEMS

參考文獻

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