Yunlong Guo's research while affiliated with Northwestern Polytechnical University and other places

Photo‐triggered shape morphing structures can be found in myriads of areas. Utilizing light as a switch can effectively control and regulate the precise deformation of structures. However, the integration of photo‐switching functions in shape‐morphing structures with complex geometries remains a challenge. Here, photoswitchable digital light processing based 4D printing high‐resolution and highly complex geometries, based on UV curable WO2.9 nanoparticle doped shape memory polymer nanocomposites is reported, which are highly deformable (stretchability up to ≈1000% at rubbery state) and fatigue resistant (repeatedly loaded >1200 times at ambient temperature). The presence of just trace WO2.9 nanoparticles (<0.20 wt.‰) contributes to the controlled photothermal property of nanocomposite via selective absorption of light, which enables reversibly photoswitchable (>50 times), spatial and remote control of 4D printing shape morphing structures. These findings offer a promising approach to expanding the applications of photo‐triggered shape‐morphing structures.

Hydrogel‐based electronics have inherent similarities to biological tissues and hold potential for wearable applications. However, low conductivity, poor stretchability, nonpersonalizability, and uncontrollable dehydration during use limit their further development. In this study, projection stereolithography 3D printing high‐conductive hydrogel for flexible passive wireless sensing is reported. The prepared photocurable silver‐based hydrogel is rapidly planarized into antenna shapes on substrates using surface projection stereolithography. After partial dehydration, silver flakes within the circuits form sufficient conductive pathways to achieve high conductivity (387 S cm⁻¹). By sealing the circuits to prevent further dehydration, the resistance remains stable when tensile strain is less than 100% for at least 30 days. Besides, the sealing materials provide versatile functionalities, such as stretchability and shape memory property. Customized flexible radio frequency identification tags are fabricated by integrating with commercial chips to complete the accurate recognition of eye movement, realizing passive wireless sensing.

Chronic wound healing remains a substantial clinical challenge. Current treatments are often either prohibitively expensive or insufficient in meeting the various requirements needed for effective diabetic wound healing. A 4D printing multifunctional hydrogel dressing is reported here, which aligns perfectly with wounds owning various complex shapes and depths, promoting both wound closure and tissue regeneration. The hydrogel is prepared via digital light process (DLP) 3D printing of the mixture containing N‐isopropylacrylamide (NIPAm), curcumin‐loaded Pluronic F127 micelles (Cur‐PF127), and poly(ethylene glycol) diacrylate‐dopamine (PEGDA575‐Do), a degradable crosslinker. The use of PEGDA575‐Do ensures tissue adhesion and degradability, and cur‐PF127 serves as an antibacterial agent. Moreover, the thermo‐responsive mainchains (i.e., polymerized NIPAm) enables the activation of wound contraction by body temperature. The features of the prepared hydrogel, including robust tissue adhesion, temperature‐responsive contraction, effective hemostasis, spectral antibacterial, biocompatibility, biodegradability, and inflammation regulation, contribute to accelerating diabetic wound healing in Methicillin‐resistant Staphylococcus aureus (MRSA)‐infected full‐thickness skin defect diabetic rat models and liver injury mouse models, highlighting the potential of this customizable, mechanobiological, and inflammation‐regulatory dressing to expedite wound healing in various clinical settings.

Photo-triggered shape morphing structures can be found in myriads of areas. Utilizing light as a switch can effectively control and regulate the precise deformation of structures. However, the integration of photo switching functions in shape morphing structures with complex geometries remains a challenge. Here, we report photo switchable digital light processing based 4D printing high-resolution and highly complex geometries, based on UV curable WO 2.9 nanoparticle doped shape memory polymer nanocomposites, which are highly deformable (stretchability up to ~1000% at rubbery state) and fatigue resistant (repeatedly loaded > 1200 times at ambient temperature). The presence of just trace WO 2.9 nanoparticles (< 0.20 wt.‰) contributes to the controlled photothermal property of nanocomposite via selective absorption of light, which enables reversibly photo switchable (＞50 times), spatial and remote control of 4D printing shape morphing structures. These findings offer a promising approach to expanding the applications of photo-triggered shape morphing structures.