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Vol. 18 (2026)

Dual-Mode Sensor with Saturated Mechanochromic Structural Color Enhanced by Black Conductive Hydrogel for Interactive Rehabilitation Monitoring

https://doi.org/10.1007/s40820-025-01963-2
Zhiyuan Sun
Macao Institute of Materials Science and Engineering (MIMSE), Faculty of Innovation Engineering, Macau University of Science and Technology, Taipa, Macao 999078, People’s Republic of China
Binhong Yu
Macao Institute of Materials Science and Engineering (MIMSE), Faculty of Innovation Engineering, Macau University of Science and Technology, Taipa, Macao 999078, People’s Republic of China
Chao Dong
Chemistry and Physics Department, College of Art and Science, The University of Texas of Permian Basin, Odessa, TX 79762, USA
Chengjun Yu
Macao Institute of Materials Science and Engineering (MIMSE), Faculty of Innovation Engineering, Macau University of Science and Technology, Taipa, Macao 999078, People’s Republic of China
Lianghe Sheng
Department of Oncology, The First Affiliated Hospital of Jinan University, Guangzhou 510630, People’s Republic of China
Zhe Cui
Macao Institute of Materials Science and Engineering (MIMSE), Faculty of Innovation Engineering, Macau University of Science and Technology, Taipa, Macao 999078, People’s Republic of China
Yaming Liu
Macao Institute of Materials Science and Engineering (MIMSE), Faculty of Innovation Engineering, Macau University of Science and Technology, Taipa, Macao 999078, People’s Republic of China
Zhenni Lu
Macao Institute of Materials Science and Engineering (MIMSE), Faculty of Innovation Engineering, Macau University of Science and Technology, Taipa, Macao 999078, People’s Republic of China
Bingda Chen
Key Laboratory of Green Printing, Institute of Chemistry, Chinese Academy of Sciences, Beijing Engineering Research Center of Nanomaterials for Green Printing Technology, Beijing National Laboratory for Molecular Sciences (BNLMS), Zhongguancun North First Street 2, Beijing 100190, People’s Republic of China
Daixi Xie
Key Laboratory of Green Printing, Institute of Chemistry, Chinese Academy of Sciences, Beijing Engineering Research Center of Nanomaterials for Green Printing Technology, Beijing National Laboratory for Molecular Sciences (BNLMS), Zhongguancun North First Street 2, Beijing 100190, People’s Republic of China
Zhandong Huang
School of Chemical Engineering and Technology, Xi’an Jiaotong University, Xi’an 710049, People’s Republic of China
Songshan Zeng
Macao Institute of Materials Science and Engineering (MIMSE), Faculty of Innovation Engineering, Macau University of Science and Technology, Taipa, Macao 999078, People’s Republic of China
Qingdong Ou
Macao Institute of Materials Science and Engineering (MIMSE), Faculty of Innovation Engineering, Macau University of Science and Technology, Taipa, Macao 999078, People’s Republic of China

Corresponding Author: Qingdong Ou

qdou@must.edu.mo

Nano-Micro Letters, Vol. 18 (2026), Article Number: 110

Abstract

Flexible and wearable sensors offer immense potential for rehabilitation medicine, but most rely solely on electrical signals, lacking real-time visual feedback and limiting trainee’s interactivity. Inspired by the structural coloration of Cyanocitta stelleri feathers, we developed a dual-mode sensor by utilizing black conductive polymer hydrogel (CPH)-enhanced structural color strategy. This sensor integrates a hydroxypropyl cellulose (HPC)-based structural color interface with a designed CPH sensing component. Highly visible light-absorbing CPH (absorption rate > 88%) serves as the critical substrate for enhancing structural color performance. By absorbing incoherent scattered light and suppressing background interference, it significantly enhances the saturation of structural color, thereby achieving a high contrast index of 4.92. Unlike the faint and hardly visible structural colors on non-black substrates, the HPC on CPH displays vivid, highly perceptible colors and desirable mechanochromic behavior. Moreover, the CPH acts as a flexible sensing element, fortified by hydrogen and coordination bond networks, and exhibits exceptional electromechanical properties, including 867.1 kPa tensile strength, strain sensitivity (gauge factor of 4.24), and outstanding durability (over 4400 cycles). Compared to traditional single-mode sensors, the integrated sensor provides real-time visual and digital dual feedback, enhancing the accuracy and interactivity of rehabilitation assessments. This technology holds promise for advancing next-generation rehabilitation medicine.


Highlights:
1 Mimicking Cyanocitta stelleri feathers, we developed a dual-mode sensor with strain-sensing and mechanochromic functions by using black conductive polymer hydrogel (CPH) substrate to enhance hydroxypropyl cellulose’s structural color.
2 The synthesized CPH, with >88% visible-light absorption, enhances color saturation by absorbing scattered light and suppressing background interference, enabling vivid mechanochromism. Fortified by noncovalent bonds, it also functions as a robust, sensitive sensor.
3 Unlike traditional single-mode sensors, this integrated sensor offers real-time visual and digital feedback, improving rehabilitation assessment accuracy and interactivity.

Keywords

Conductive hydrogel Structural color Hydroxypropyl cellulose Dual-mode sensor Rehabilitation monitoring
Sun, Zhiyuan, Binhong Yu, Chao Dong, Chengjun Yu, Lianghe Sheng, Zhe Cui, Yaming Liu, Zhenni Lu, Bingda Chen, Daixi Xie, Zhandong Huang, Songshan Zeng, and Qingdong Ou. 2026. “Dual-Mode Sensor With Saturated Mechanochromic Structural Color Enhanced by Black Conductive Hydrogel for Interactive Rehabilitation Monitoring”. Nano-Micro Letters 18 (January):110. https://doi.org/10.1007/s40820-025-01963-2.
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