| 摘要: | 以表面電漿共振(surface plasmon resonance, SPR)系統製成的DNA微陣列晶片，能同時檢測成千上萬個寡核苷酸(oligonucleotide)樣本，是一種高速、精確的感測技術。除了速度與精確度之外，元件微型化也逐漸受到科學家的重視。DNA微陣列晶片若能兼具高速、精確、微型這三項特點，對基因定序、個人健康管理、甚至精準醫療都有極大的助益。 然而，微型化SPR感測晶片是艱難的任務。這是因為目前最常見的SPR感測系統，需要很多零件，包含: 龐大的稜鏡(厚度 > 1cm)、載玻片、偏振片、複雜的反射角追蹤系統、以及匹配折射率的專用油(index-matching oil)來確保稜鏡與載玻片之間的光學耦合。這些複雜的零件，讓SPR感測晶片的操作變得更繁瑣、耗時，大大增加微型化的難度與成本。 本計畫希望在兩年內解決上述的難題。由InGaN量子井及金屬薄膜引發的SPR效應，牽涉到光子局部能階密度(photonic local density of states)的分佈，對光學近場內的折射率變化極度敏感，這種主動式的SPR效應，與傳統被動式的SPR感測機制不同。而且，InGaN量子井具備天然的波導(waveguide)結構、也有自發性的偏振光、還有極高的化學穩定性、更能作為SPR系統中的增益介質(gain medium)。因此，我們能以厚度僅約0.04 cm的InGaN量子井磊晶片，取代上述的稜鏡、載玻片、偏振片、角度追蹤系統、匹配折射率的油，讓SPR的架構更簡化，也讓晶片變的更靈敏。 ;Surface-plasmon-resonance-based (SPR-based) DNA (deoxyribonucleic acid) microarray biochip is a high throughput, high sensitivity assay technique, being able to simultaneously monitor numerous hybridizing events between complementary oligonucleotides. While the ongoing research efforts are mostly dedicated to enhance speed and sensitivity of the sensor, a third consideration has become increasingly important: compactness, which is strongly desired in DNA sequencing, personal health management, and precision medical treatment. However, miniaturizing SPR-based biosensing structure remains elusive as it entails complicated optical gears, including a bulky prism (thickness > 1 cm), a glass slide, polarizers, an optical tracking system, and the index-matching oil to ensure the optical coupling between the prism and the glass slide. These onerous designs/procedures make on-site and personal diagnoses extremely difficult. In this two-year project, we aim to revolutionize the architecturing of SPR-based DNA microarray biochips by eliminating all the above cumbersome with a 0.4-mm-thin InGaN quantum well (QW) wafer, and achieve the performances superior to those reported by the conventional devices. The QW-based active SPR modality is closely related to photonic local density of states, being extremely sensitive to local variation of refractive index. The new device is realized by many unique advantages of InGaN QW in SPR biosensing, including: i) The natural waveguide-like structure, rendering the prism-free SPR effect. ii) Inherent polarized emission, eliminating the external polarizers. iii) Chemical inertness, avoiding the index-matching oil. iv) Gain-medium function, enhancing the detection sensitivity. The approach presented here chains the techniques in III-nitride growth and the specialties in SPR biosensing, opening a new landscape for the development of compact and high-throughput diagnostic devices. |
