From engineering improved device performance to unraveling the breakdown of classical heat transfer laws, far-field optical temperature mapping with nanoscale spatial resolution would benefit diverse areas. However, these attributes are traditionally in opposition because conventional far-field optical temperature mapping techniques are inherently diffraction limited. Optical super-resolution imaging techniques revolutionized biological imaging, but such approaches have yet to be applied to thermometry. Here, we demonstrate a super-resolution nanothermometry technique based on highly doped upconverting nanoparticles (UCNPs) that enable stimulated emission depletion (STED) super-resolution imaging. We identify a ratiometric thermometry signal and maintain imaging resolution better than ~120 nm for the relevant spectral bands. We also form self-assembled UCNP monolayers and multilayers and implement a detection scheme with scan times >0.25 μm 2 /min. We further show that STED nanothermometry reveals a temperature gradient across a joule-heated microstructure that is undetectable with diffraction limited thermometry, indicating the potential of this technique to uncover local temperature variation in wide-ranging practical applications.

中文翻译：

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通过上转换纳米粒子的受激发射损耗成像进行光学超分辨率纳米测温


从工程改进设备性能到解开经典传热定律的谜题，具有纳米级空间分辨率的远场光学温度测绘将使各个领域受益。然而，这些属性传统上是相反的，因为传统的远场光学温度测绘技术本质上是衍射限制的。光学超分辨率成像技术彻底改变了生物成像，但此类方法尚未应用于测温。在这里，我们展示了一种基于高掺杂上转换纳米粒子（UCNP）的超分辨率纳米测温技术，该技术能够实现受激发射损耗（STED）超分辨率成像。我们识别比例测温信号，并保持相关光谱带的成像分辨率优于约 120 nm。我们还形成自组装UCNP单层和多层，并实施扫描时间>0.25 μm 2 /min的检测方案。我们进一步表明，STED 纳米测温法揭示了焦耳加热微观结构上的温度梯度，这是衍射极限测温法无法检测到的，表明该技术在广泛的实际应用中揭示局部温度变化的潜力。