以微米孔洞結構進行電化學生物分子感測元件之研發

Abstract

近年來人口高齡化是世界各國共同需要面對的課題，也因此預防醫學已然成為未來醫療的重要趨勢。聯合國於2019年出版的全球高齡人口報告 (World Population Prospects 2019) 中，推估全球高齡人口比率成長最快的國家與地區，臺灣僅次於南韓與新加坡，名列全球第三。很顯然地，對於台灣社會這也是迫切需要投入心力的研究領域。隨著經濟社會的發達、醫療技術的進步，人們渴望藉由日常簡易紀錄、檢測身體指數來達到及早發現與及早治療的目的，如此一來不但可以讓醫療資源更有效的被運用，也可減輕照顧者的負擔。所以，以定點照護為主要訴求之生物感測器需求量逐年上升。為顧及一般大眾、居家照顧人員或機構的使用，體積小、可攜式、具傳輸功能、適當的靈敏度、操作簡易及低成本等特性將會是該領域研究需要優先考量的要素。 本論文提出以電化學阻抗量測的方法作為檢測的基礎，將三極式電化學量測的兩種電極（工作電極及輔助電極）縮小至一具奈米孔洞生物晶片上。藉由電腦模擬電化學電解液電流密度來判斷生物晶片之檢測靈敏度。由模擬結果可以得知，當孔徑為1 μm時，其電流密度為孔徑為100 μm時的73.28倍。再輔以調整工作電極及輔助電極之間的氧化層厚度，藉此提昇電化學量測效率。結果為當氧化層厚度200 nm時，最大電流密度為140.02 (A/m2)；氧化層厚度1000 nm時，最大電流密度為22.794 (A/m2)，前者是後者的 6.14 倍。所以當孔徑較小且中間氧化層厚度較薄時，具有較高的電解液電流密度。在衡量製程成本下，最終選擇孔徑 30 μm，且中間氧化層厚度為400 μm為最適化的奈米孔生物感測器。最後，本論文利用Biotin作為連結分子，利用電化學阻抗分析法，驗證此3D奈米孔生物晶片之可行性。實驗結果顯示，隨著抗原濃度增大，電子傳遞電阻的變化量 (ΔRct) 與其呈現相當線性之關係，可見此生物晶片檢測之穩定性。

In recent years, population aging has been a common issue which is needed to be solved by countries around the world. Therefore, preventive healthcare has become an important trend in the future of the medical field. In the World Population Prospects 2019 (the United Nations), a report published in 2019, it is estimated that Taiwan ranks third in the world after South Korea and Singapore as the countries and regions with the fastest-growing elderly population rates. That is why preventive healthcare is an urgent field for Taiwanese society. With the advancement of medical technology, people look forward to monitoring some symbolic body indices with daily records and using this information to discover diseases at an early stage. Medical systems can provide people with early diagnosis and prompt treatment. Public health and medical resources can be used more effectively, and caregivers' burden can be relieved. Therefore, the demand for biosensors for point of care testing is increasing year by year. Considering the general public, home caregivers, and institutional use, small size, portability, transmission capability, appropriate sensitivity, ease of operation, and low cost will be the priority factors in this research field. In this thesis, we propose a 3D nanopore biochip using electrochemical impedance measurement as the basis of detection. The working electrode and the auxiliary electrode are integrated into the biochip in this three electrodes measurement system. The computer simulation of electrochemical electrolyte current density is used to determine the sensitivity of biochip detection. The simulation results show that the current density is 73.28 times higher when the pore diameter is 1 μm than 100 μm. To improve the sensitivity of electrochemical measurement, the thickness of the oxide layer between the working electrode and the auxiliary electrode was adjusted. The result of the maximum current density is 140.02 (A/m2) when the middle oxide layer thickness is 200 nm and 22.794 (A/m2) when the middle oxide layer thickness is 1000 nm. The former is 6.14 times higher than the latter. Therefore, the electrolyte current density is higher when the pore diameter is smaller and the thickness of the middle oxide layer is thinner. Considering the process cost, a 3D nanopore biosensor with a pore size of 30 μm and a middle oxide layer thickness of 400 nm is chosen as the optimal configuration. Finally, the feasibility of this 3D nanopore biochip was verified by electrochemical impedance analysis with biotin as the linking molecule. The experimental results showed that the change of electron transfer resistance (ΔRct) was linear with the antigen concentration, indicating the stability of this biochip.