自組裝單分子層修飾在矽奈米感測器應用

Abstract

本研究主要在於利用焦耳熱效應選擇性移除自組裝單分子層聚乙二醇矽烷(MPEG-sil)以及十八烷基三氯矽烷(OTS)，選擇性修飾目的為降低非偵測區外非專一性吸附來提高低濃度生醫檢測靈敏度。本研究利用離子佈值技術在矽奈米元件通道中間創造出一低離子濃度參雜的元件結構作為進行焦耳熱的加熱區，結合低濃度參雜區域電阻較高以及矽奈米元件中低濃度參雜區域對表面電位變化較為靈敏的特性，成功地將焦耳熱技術與生醫感測結合，並將streptavidin以及DNA修飾於元件感測區，同時利用自組裝單分子層做保護層有別於傳統利用鐵氟龍或PMMA，可有效地降低施加焦耳熱效應的功率並維持元件的次臨界擺幅以利後續的生醫感測應用。由原子力顯微鏡的量測證明可以將加熱區表面的單分子層燒除，進而修飾可以捕捉待測物的生物分子，並與帶有螢光的待測物進行結合，螢光出現的位置也與原子力顯微鏡對應，證明選擇性修飾的完整性。對於電性量測而言，因為選擇性修飾可有效地將待測檢體集中於矽奈米元件高靈敏度感測區而提升了偵測速度以及偵測極限，實驗結果證明，有選擇性修飾的元件偵測streptavidin極限可以推至15 pM，而沒有的只能至150 pM。由本研究的結果我們可以預期此技術將可成功的在早期生醫檢測領域做出重大的貢獻。

In this study, selective ablation of self-assembly monolayer methoxy-poly (ethylene glycol) silane (MPEG-sil) and Octadecyltrichlorosilane (OTS) on silicon nanoelectronic devices by localize joule heating was demonstrated for biosensing application. Lightly doped region in a silicon nanoelectronic device is usually functioned as the active channel which is sensitive to the change of surface potential. And, the resistance of this region is higher compared to other regions in a device so that the electric power consumed. SAMs on lightly doped region were ablated during Joule heating leaving the rest area passivated. The subthreshold swing of nanoelectronic device almost kept unchanged after Joule heating. AFM was adopted to characterize the device surface before and after Joule heating and selective biomolecule modifications. Analysis of fluorescent results showed consistency with AFM results that selectivity in surface modofications was achieved. We found that SAM-ablated device possess potential in the increase of sensing response and in the increase of sensitivity for low concentration detection. In streptavidin detection, the device with selective modification exhibited a detection limits of 15 pM, while the device without selective modification showed an order of magnitude higer in its limit of detection.