Acosta Laura K, Law Cheryl Suwen, Lim Siew Yee, Abell Andrew D, Marsal Lluis F, Santos Abel
School of Chemical Engineering and Advanced Materials, The University of Adelaide, Adelaide, South Australia 5005, Australia.
Department of Electronic, Electric, and Automatics Engineering, Rovira i Virgili University, Tarragona 43007, Spain.
ACS Appl Mater Interfaces. 2021 Mar 31;13(12):14394-14406. doi: 10.1021/acsami.1c00914. Epub 2021 Mar 18.
Nanoporous anodic alumina optical microcavities (NAA-μQVs) with spectrally tunable resonance band and surface chemistry are used as model light-confining photonic crystal (PC) platforms to elucidate the combined effect of spectral light confinement features and surface chemistry on optical sensitivity. These model nanoporous PCs show well-resolved, spectrally tunable resonance bands (RBs), the central wavelength of which is engineered from ∼400 to 800 nm by the period of the input anodization profile. The optical sensitivity of the as-produced (hydrophilic) and dichlorodimethylsilane-functionalized (hydrophobic) NAA-μQVs is studied by monitoring dynamic spectral shifts of their RB upon infiltration with organic- and aqueous-based analytical solutions of equally varying refractive index, from 1.333 to 1.345 RIU. Our findings demonstrate that hydrophilic NAA-μQVs show ∼81 and 35% superior sensitivity to their hydrophobic counterparts for organic- and aqueous-based analytical solutions, respectively. Interestingly, the sensitivity of hydrophilic NAA-μQVs per unit of spectral shift is more than 3-fold higher in organic than in aqueous matrices upon equal change of refractive index, with values of 0.347 ± 0.002 and 0.109 ± 0.001 (nm RIU) nm, respectively. Conversely, hydrophobic NAA-μQVs are found to be slightly more sensitive toward changes of refractive index in aqueous medium, with sensitivities of 0.072 ± 0.002 and 0.066 ± 0.006 (nm RIU) nm in water- and organic-based analytical solutions, respectively. Our advances provide insights into critical factors determining optical sensitivity in light-confining nanoporous PC structures, with implications across optical sensing applications, and other photonic technologies.
具有光谱可调谐共振带和表面化学性质的纳米多孔阳极氧化铝光学微腔（NAA-μQVs）被用作模型光限制光子晶体（PC）平台，以阐明光谱光限制特征和表面化学性质对光学灵敏度的综合影响。这些模型纳米多孔PC显示出分辨率良好、光谱可调谐的共振带（RB），其中心波长通过输入阳极氧化轮廓的周期从约400nm设计到800nm。通过监测用折射率同样从1.333到1.345RIU变化的有机和水基分析溶液渗透时其RB的动态光谱位移，研究了所制备的（亲水的）和二氯二甲基硅烷功能化的（疏水的）NAA-μQVs的光学灵敏度。我们的研究结果表明，对于有机和水基分析溶液，亲水的NAA-μQVs分别比其疏水对应物表现出约81%和35%的更高灵敏度。有趣的是，在折射率同等变化时，亲水的NAA-μQVs在有机基质中的每单位光谱位移灵敏度比在水基质中高3倍以上，分别为0.347±0.002和0.109±0.001（nm RIU）nm。相反，发现疏水的NAA-μQVs在水介质中对折射率变化稍更敏感，在水基和有机基分析溶液中的灵敏度分别为0.072±0.002和0.066±0.006（nm RIU）nm。我们的进展为确定光限制纳米多孔PC结构中光学灵敏度的关键因素提供了见解，对光学传感应用及其他光子技术具有启示意义。
