Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, CA, 90095, USA.
John A. Paulson School of Engineering and Applied Sciences, Kavli Institute for Bionano Science and Technology, Harvard University, Cambridge, MA, 02138, USA.
Adv Mater. 2018 May;30(21):e1800468. doi: 10.1002/adma.201800468. Epub 2018 Apr 11.
Living organisms ubiquitously display colors that adapt to environmental changes, relying on the soft layer of cells or proteins. Adoption of soft materials into an artificial adaptive color system has promoted the development of material systems for environmental and health monitoring, anti-counterfeiting, and stealth technologies. Here, a hydrogel interferometer based on a single hydrogel thin film covalently bonded to a reflective substrate is reported as a simple and universal adaptive color platform. Similar to the cell or protein soft layer of color-changing animals, the soft hydrogel layer rapidly changes its thickness in response to external stimuli, resulting in instant color change. Such interference colors provide a visual and quantifiable means of revealing rich environmental metrics. Computational model is established and captures the key features of hydrogel stimuli-responsive swelling, which elucidates the mechanism and design principle for the broad-based platform. The single material-based platform has advantages of remarkable color uniformity, fast response, high robustness, and facile fabrication. Its versatility is demonstrated by diverse applications: a volatile-vapor sensor with highly accurate quantitative detection, a colorimetric sensor array for multianalyte recognition, breath-controlled information encryption, and a colorimetric humidity indicator. Portable and easy-to-use sensing systems are demonstrated with smartphone-based colorimetric analysis.
生物体普遍显示出适应环境变化的颜色，这依赖于细胞或蛋白质的柔软层。将软材料应用于人工自适应颜色系统，促进了用于环境和健康监测、防伪和隐形技术的材料系统的发展。在这里，报道了一种基于单块共价键合到反射衬底上的水凝胶的水凝胶干涉仪，作为一种简单而通用的自适应颜色平台。类似于变色动物的细胞或蛋白质软层，柔软的水凝胶层会迅速响应外部刺激改变其厚度，从而实现即时变色。这种干涉色提供了一种可视化和可量化的方法来揭示丰富的环境指标。建立了计算模型并捕获了水凝胶响应性溶胀的关键特征，阐明了该广泛平台的机制和设计原理。基于单一材料的平台具有出色的颜色均匀性、快速响应、高稳健性和易于制造的优点。其多功能性通过各种应用得到证明：具有高度精确定量检测的挥发性蒸气传感器、用于多分析物识别的比色传感器阵列、呼吸控制信息加密以及比色湿度指示器。演示了基于智能手机的比色分析的便携式和易于使用的传感系统。
