| Author: | Zhang, Junze |
| Title: | Study of photochromic and hydrogel materials for smart wearable applications |
| Advisors: | Xu, Bingang (SFT) |
| Degree: | Ph.D. |
| Year: | 2026 |
| Department: | School of Fashion and Textiles |
| Pages: | xxvii, 179 pages : color illustrations |
| Language: | English |
| Abstract: | With the rapid development of wearable technology, smart materials that combine sustainability, multifunctional integration, and biocompatibility have become a research hotspot. Photochromic materials have significant potential in information security encryption and photopatterned displays, while hydrogels are indispensable in bioelectronic interfaces and implantable medical devices. However, traditional materials face challenges such as poor colorfastness, insufficient environmental stability, and difficulty balancing mechanical properties and biocompatibility, which seriously restrict their practical applications. Developing new materials with desirable properties of preparation scalability, performance stability, and environmental/biological compatibility is crucial for promoting sustainable electronic textiles and smart healthcare devices. In this research, we have designed sustainable and smart wearables with excellent photochromic properties for photo-patterning and information security encryption applications, and developed highly stretchable and biocompatible wearable devices with excellent physical and electric properties for bioelectronic and healthcare applications. Firstly, a new kind of fiber-based photochromic wearables is designed and developed by combining cotton fabric with a MoO3-based self-adhesive polymer network and long chain silyl group. The prepared photochromic textile wearable has exhibited excellent fatigue resistance and favorable reversibility (> 40 cycles), rapid light response (reach color saturation with a UV dose of 60 kJ m⁻²), outstanding color retention capability (> 90 days), and desirable biocompatibility (cell viability > 100%). In addition, the prepared photochromic textiles could maintain a fast light response and excellent color retention even after experiencing repeated washing (20 cycles). Moreover, the photo-patterning photochromic wearables are verified by resisting the deterioration of acid solution, alkali solution, and sweat (pH 2.0–9.0) as well as keeping clear patterns under sunlight irradiation. As a demonstration of the applications, fiber-based photochromic textile wearables are made and employed for the sustainable applications of rewritable photo-patterning and information security encryption. Then, a fiber-based photochromic wearable is designed and developed by covalently bonding MoO₃ microcapsule (MM) nanoparticles with a sheath-core structure into pristine cotton fabrics and integrating MM nanoparticles with sodium alginate (SA) through electrostatic forces and peptide linkages. The resulted photochromic wearable exhibits reversible color transformation and exceptional photochromic characteristics, including remarkable fatigue resistance (> 40 cycles), rapid light response, and outstanding color retention (> 60 days). Moreover, the photochromic wearable exhibits exceptional stability in diverse harsh environments, including different acid-base solutions (pH 2.0-9.0), various temperature (-30–60°C), indoor light and sunshine exposure, and repeated laundering (> 15 cycles). This photochromic fabric exhibits exceptional wearability, boasting remarkable flexibility (17 mm), and biocompatibility (cell viability > 95%). Notably, rewritable T-shirt and QR code information security encryption systems are demonstrated, highlighting their potential in customizable designs, flexible rewritable textiles, and information security encryption. Furthermore, a multifunctional gelatin-based biogel (G-ZCX) is designed by integrating Zinc pyrrolidone carboxylate (PCA-Zn), cellulose nanofibers (CNF), and xanthan gum (XG) through synergistic ionic crosslinking and hydrogen bonding. This biogel combines low modulus (0.1-0.5 MPa), high stretchability (286.7%), and fatigue resistance (> 10,000 cycles), closely matching the mechanical properties of biological tissues. The biogel exhibits high ionic conductivity and negligible inflammatory responses both in vitro and in vivo. As a wearable sensor, it enables full-range motion detection and high-accuracy gesture recognition (99.8% via 1D-CNN). As demonstration of applications, it stably acquires multi-modal electrophysiological signals (electromyography (EMG)/ electrocardiography (ECG)/ electrooculography (EOG)/ electroencephalography (EEG)) with an excellent signal-to-noise ratio (SNR: 26.3 dB) and minimal attenuation over 24 h. For implantable applications, cytotoxicity tests and rat subcutaneous implantation experiments confirmed its excellent biocompatibility, and the inflammatory response was essentially eliminated after 14 days. This work provides a general strategy and a versatile platform for highly stretchable and biocompatible hydrogel materials with promising functions for various applications such as bioelectronics, personalized rehabilitation, and implantable medical devices. This comprehensive study demonstrates the remarkable versatility of wearable devices with color-changing and biocompatible sensing capabilities and their associated functionalized systems. The innovative approaches and advanced designs outlined in these studies demonstrate significant improvements in photochromic performance, biocompatible performance, and application potential. Consequently, these findings pave the way for the development of sustainable and biocompatible wearable functionalities that are more intelligent, practical, human-centric, and sustainable. |
| Rights: | All rights reserved |
| Access: | open access |
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