We report a self-assembly composite photonic crystal with humidity-controlled structure color, towarding to easy humidity detection by a smartphone. As the key issue, the composite photonic sensor is developed via quasi-coating the silica colloidal photonic crystal (SPC) with hydrophilic metal-organic-framework (MOF). Thus the sensor combines the complementary adsorption properties between SPC and MOF, so that realizes a sensitive humidity sensor with wide dynamic detection range. The performance of the sensor was validated via water vapor testing, that its reflection spectrum shifts ~9 nm towards to longer wavelength with the concentration from 500ppm to 20000ppm under room temperature. The humidity-controlled structure color of the sensor paves a way for smartphone detection, so that a simple yet powerful smartphone spectrometer is established to analyze the reflection spectrum of the sensor. Thus, a lab-on-a-phone humidity measurement platform is developed. Thanks to the portability, low-cost and user-friendliness, this platform is promising to be a powerful tool for humidity IoT application, from personal health monitoring to environment monitoring.

中文翻译：

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自组装复合光子晶体：通过智能手机轻松检测湿度

我们报告了一种具有湿度控制结构颜色的自组装复合光子晶体，旨在通过智能手机轻松检测湿度。作为关键问题，复合光子传感器是通过用亲水性金属有机框架（MOF）准涂覆二氧化硅胶体光子晶体（SPC）来开发的。因此，该传感器结合了 SPC 和 MOF 之间互补的吸附特性，从而实现了具有宽动态检测范围的灵敏湿度传感器。通过水蒸气测试验证了传感器的性能，其反射光谱在室温下从 500 ppm 到 20000 ppm 的浓度向更长的波长移动~9 nm。传感器的湿度控制结构颜色为智能手机检测铺平了道路，这样就建立了一个简单而强大的智能手机光谱仪来分析传感器的反射光谱。因此，开发了手机实验室湿度测量平台。由于便携性、低成本和用户友好性，该平台有望成为湿度物联网应用的强大工具，从个人健康监测到环境监测。