Enhancement of the luminescent output of pressure-sensitive paint (PSP) has been achieved by adding silver nanostructures into a standard formulation by taking advantage of a metal-enhanced fluorescence effect. Traditionally, metal-enhanced fluorescence has been used in microscopy or thin-film sensing. However, in PSP applications, the luminescent film is applied onto large surfaces by using conventional paint application techniques, and imaging is acquired from longer distances. As such, many of the techniques deployed for maximum enhancement (such as careful spacing of the metal centers) is not easily achievable. Initial trials consisted of adding silver nanostructures into a PSP formulation. The luminescent enhancement was highly dependent on the concentration of the oxygen-sensitive dye. At very low concentrations of the dye (<10 μM), enhancements more than a factor of 3 could be achieved. However, as the concentration of the dye increased (∼800 μM), the enhancement effect reduced and eventually diminished the signal. This was due to the dark color of the silver and the decrease in the distance between the dye and the silver nanostructures, leading to quenching of luminescence. To alleviate this problem, silver nanoparticles were coated with a silica shell, which acted as a spacer keeping the dye and silver nanoparticles at a suitable distance from each other to maximize the luminescence enhancement without quenching being observed regardless of the nanoparticle concentration. This resulted in an enhancement factor of more than 1.5. Excited-state lifetime measurements were also acquired to verify that the enhancement was due to metal-enhanced fluorescence.

中文翻译：

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添加二氧化硅涂层的银纳米颗粒以增强压力敏感涂料的发光强度

通过利用金属增强的荧光效应将银纳米结构添加到标准配方中，已经实现了压敏涂料（PSP）发光输出的增强。传统上，金属增强的荧光已用于显微镜或薄膜感测。然而，在PSP应用中，通过使用常规的涂料施加技术将发光膜施加到大表面上，并且从更长的距离获取成像。因此，为最大程度地增强（例如金属中心的仔细间隔）而部署的许多技术都不容易实现。初步试验包括在PSP配方中添加银纳米结构。发光增强高度依赖于氧敏感性染料的浓度。在极低浓度的染料（<10μM）下，可以实现超过3倍的增强。但是，随着染料浓度的增加（约800μM），增强效果降低并最终减弱了信号。这是由于银的颜色深以及染料与银纳米结构之间距离的减小，导致发光猝灭。为了减轻该问题，用二氧化硅壳涂覆银纳米颗粒，该二氧化硅壳用作间隔物，使染料和银纳米颗粒彼此保持合适的距离以最大化发光增强，而与纳米颗粒浓度无关而未观察到猝灭。这导致增强系数大于1.5。还获得了激发态寿命测量值，以验证这种增强是由于金属增强的荧光引起的。