以雷射干涉微影技術製作奈米圓盤及孔洞陣列之奈米電漿感測器

Abstract

奈米電漿(nanoplamonic)效應為一種在特定奈米結構上所發生之光學現象。因此現象為非接觸式之光學偵測、不須對待測樣本進行標定 (label-free)且具有高靈敏度，因此近年來已被廣泛的使用在許多生化樣品的感測。為了製造奈米電漿所需之奈米結構，文獻中已經開發了很多方法，但是只有很少數的奈米結構製程方法能夠以低成本、穩定地產出大面積的奈米結構。而且，由於奈米電漿訊號通常有很大的半高寬 (full width at half maximum, FWHM)，品質因數 (figure of merit, FoM) 通常不高，導致不容易偵測到訊號。在本篇論文中，我們提出了一個製程方法，結合雷射干涉微影技術 (laser interference lithography, LIL) 與掀離 (lift-off) 的方式，在玻璃上做出週期性的奈米金圓盤結構，以增加感測器的FoM。另外，我們也結合了LIL和奈米壓印微影技術 (nanoimprint lithography, NIL)，製作出連續性的金奈米孔洞週期結構。在製程前，我們先使用時域有限差分 (finite-difference time-domain, FDTD) 模擬來決定奈米結構的最佳參數。做完奈米結構之後，更進一步地將奈米結構與微流道結合，進行生物分子的感測。我們的製程方法能夠產出大面積 (~ 5 mm × 5 mm) 的金奈米圓盤陣列，並且能夠做出任意的週期及金膜厚度，此金奈米圓盤陣列感測器的靈敏度與FoM分別為190 nm/RIU以及2.69。另一方面，連續性的金奈米孔洞感測器之靈敏度與FoM為 244 nm/RIU與2.38。此外，我們也成功地使用奈米孔洞結構之感測器量測了免疫球蛋白G (immunoglobulin G, IgG)分子。綜合以上所述，此金奈米圓盤及奈米孔洞結構為高靈敏度之奈米電漿感測器，並有潛力用於更廣泛的生醫感測應用，如定點照護(point-of-care)檢測。

Nanoplasmonic phenomena occur near nanostructure. Due to its non-contact, label-free nature, nanoplasmonic sensing has been applied to lots of biochemical sensing applications recently. In order to fabricate nanoplamonic substrate, many nanostructure fabrication methods have been developed. However, few are capable of achieving stable, large-area, and low-cost fabrication of the metal nanostructure. Moreover, due to the wide full width at half maximum (FWHM) of the spectrum, the figure of merit (FoM) of nanoplasmonic sensors are often low, causing its insensibility in detection. In our research, we propose a fabrication method combining laser interference lithography (LIL) and lift-off procedure to produce an isolated periodic gold nanostructure on glass substrate. LIL is also integrated with nanoimprint lithography (NIL) to fabricate a continuous periodic gold nanohole array. We first did FDTD simulation to determine the best parameters of the nanostructure. After fabricating the nanoplamonic sensor, we combined the nanostructure with a microfluidic chip to do bio-molecule detection. With this novel nanofabrication method, large-area (~ 5 mm × 5 mm) gold nanodisks array can be fabricated, and the sensitivity and FoM of the nanodisks can reach 190 nm/RIU and 2.69. On the other hand, the sensitivity and FoM of gold nanohole array is as high as 244 nm/RIU and 2.38. To prove the sensors can be applied to biosensing, these two nanoplasmonic sensors are used to detect immunoglobulin G (IgG) molecules. These results have shown their promising contribution in the application of point-of-care diagnosis.