This method pioneers a versatile approach to broaden the design space for 4D printing and will be compatible with a wide range of active materials meeting various requirements in diverse potential applications.Ĭontinuously smooth gradients dual-responsiveness gradient 4D printing nonuniform self-morphing strain mismatch. Furthermore, we demonstrate dual-stimuli self-morphing structures by printing the graded water-responsive elastomer materials onto a heat-shrinkable shape memory polymer, which could produce different shape changes in response to humidity and different temperatures. The shape-shifting results can be predicted by the established mathematical model and computational simulations. The variation of swelling ratio mismatch between the two layers can be delicately regulated, which results in the programmable nonuniform shape transformation. By modeling and printing graded active materials with water swelling properties, we can configure continuously smooth gradients of volume fraction of the active material in bilayer structures. Here, we present a novel gradient four-dimensional (4D) printing method toward biomimetic nonuniform, dual-stimuli self-morphing. Therefore, the designed scaffold could act as endomysium to enable the infiltration of muscle fibers into the channels.Programmable nonuniform deformation is of great significance for self-shape-morphing systems that are commonly seen in biological systems and also has practical applications in drug delivery, biomedical devices and robotics, etc. Skeletal muscle is a hierarchical organization where the muscle fibers are encapsulated in microchannels known as endomysium. “I believe that the designed scaffold can have multiple applications with tubular structures such as muscle, tendon, and nerve,” said Kim. Furthermore, controlling the mechanical properties of the scaffold would enable versatile applications of the microchanneled collagen/hydroxyapatite scaffold. Going forward, the researchers will investigate enhancing the mechanical properties of the scaffold. Consequently, the in vivo studies have suggested excellent infiltration of cells into microchannels. In the case of the microchanneled collagen/hydroxyapatite scaffold, the researchers noted significantly higher water-absorbing capability, compared to a conventional collagen scaffold, as a result of the capillary pressure supplied by the microchannels. They followed that by one-way shape morphing (4D printing) and coating processes.Ĭollagen is known as a hydrophilic material, and numerous in vivo studies have suggested it possesses excellent cellular activities. The researchers printed immiscible polymer blends that act as a double negative template in order to fabricate the the biomimetic collagen/hydroxyapatite hierarchical scaffold. “This was achieved through a 4D printing strategy, where one-way shape morphing is used.” “Since the fabrication of biomimetic scaffold is a challenging issue, the innovation of this study lies in adding extra hierarchy to the structure in the form of microchannels,” said author Geun Hyung Kim. The microchannels have induced growth of blood vessels in a mouse model. The team designed a microchannel scaffold made of a collagen and hydroxyapitite combination, with each strut consisting of micrometer-scaled microchannels. Mahadevan aef Author affiliations Abstract Recent progress in additive manufacturing and materials engineering has led to a surge of interest in shape-changing plate and shell-like structures. In Applied Physics Reviews, from AIP Publishing, researchers from Sungkyunkwan University in South Korea present a solution to address the challenge of fabrication of a biomimetic scaffold. Mechanics of biomimetic 4D printed structures Wim M. Many researchers have consequently focused on trying to create a biomimetic scaffold that induces vascularization to enable bone tissue regeneration and spinal fusion. While autogenous bone grafts have long been considered the reference standard for spinal fusion, painful pseudoarthrosis remains a leading cause of poor clinical outcomes. A schematic showing the osteogenesis and angiogenesis of the fabrication of mineralized, microchanneled collagen scaffold. Surface, cross-sectional optical/SEM images showing the uniaxially aligned surface patterns and microchannels within the struts of the fabricated collagen scaffolds. Matsumoto Georgia Institute of Technology Ralph G Nuzzo. In the past two decades, there has been marked increase in the number of people over 65 years in age who have needed spinal fusion surgery. Biomimetic 4D printing Request PDF Biomimetic 4D printing January 2016 DOI: Authors: Amelia Gladman Harvard University Elisabetta A. WASHINGTON, Spinal fusion is frequently performed to restore spinal stability in patients with spinal diseases, such as spinal stenosis, vertebral fractures, progressive deformities, and instability. From the Journal: Applied Physics Reviews
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