Optically controlled grasping-slipping robot moving on tubular surfaces

Stimuli-responsive polymers provide unmatched opportunities for remotely controlled soft robots navigating in complex environments. Many of the responsive-material-based soft robots can walk on open surfaces, with movement directionality dictated by the friction anisotropy at the robot-substrate interface. Translocation in one-dimensional space such as on a tubular surface is much more challenging due to the lack of efficient friction control strategies. Such strategies could in long term provide novel application prospects in, e.g. overhaul at high altitudes and robotic operation within confined environments. In this work, we realize a liquid-crystal-elastomer-based soft robot that can move on a tubular surface through optical control over the grasping force exerted on the surface. Photoactuation allows for remotely switched gripping and friction control which, together with cyclic body deformation, enables light-fueled climbing on tubular surfaces of glass, wood, metal, and plastic with various cross-sections. We demonstrate vertical climbing, moving obstacles along the path, and load-carrying ability (at least 3 × body weight). We believe our design offer new prospects for wirelessly driven soft micro-robotics in confined spacing.publishedVersionPeer reviewe

4D printing: Pragmatic progression in biofabrication

Progress in three-dimensional (3D) printing of shape memory polymers (SMPs) has produced dynamic and 3Dprinted assemblies that can be shaped fast and modified for specific and multifaceted designs. Technology, biochemistry, medicine, computer science and biomaterials are among the areas of specialization, where 3D and four-dimensional (4D) printing techniques have penetrated to herald the next generation of manufacturing processes. Through layer-by-layer addition of diverse materials, 3D printing allows intricate assemblies with high precision. In today’s additive manufacturing (AM), 4D printing encapsulates additional magnitude, which is time. Intelligent materials that deform or change color emit an electrical current that becomes bioactive or performs a specific function in response to an external stimulus overlay to manufacture dynamic 3D structures, through a technique known as 4D printing. With this modern dimension, 3D-printed substances can alter their form by themselves, concluding the impact of peripheral stimuli, such as light, heat, electricity and magnetic field, among others. For instance, the cartilage healing and physiological maturation techniques promote bone marrow to differentiate into osteoblasts. SMPs have also been developed as tools and stages for biomedical study. Summarily, this study focuses on a systematic compendious review of 3D and 4D printing techniques and their implications in biomedical techniques. Specific technologies intend to focus on such intelligent materials, and therefore it is essential to modernize the current voxel-based analysis, design methodology and explore effective printable technologies for fabricating organic components. Health professionals will benefit from 4D printing, especially in areas where 3D printing is not available. 4D printing allows for the construction of a three-dimensional building by layering smart material and using computer-operated computer-aided design (CAD) data. It presents a new level of translation over time, in which elements like heat, moisture, and duration affect printed materials. This breakthrough has the potential to make a difference in the health sector, especially when smarter and more sophisticated surgical implants, equipment, and technology become available. 4D printing methods might now be used by medical researchers to improve quality of care

Future of additive manufacturing: Overview of 4D and 3D printed smart and advanced materials and their applications

© 2020 Elsevier B.V. 4D printing is an emerging field in additive manufacturing of time responsive programmable materials. The combination of 3D printing technologies with materials that can transform and possess shape memory and self-healing capabilities means the potential to manufacture dynamic structures readily for a myriad of applications. The benefits of using multifunctional materials in 4D printing create opportunities for solutions in demanding environments including outer space, and extreme weather conditions where human intervention is not possible. The current progress of 4D printable smart materials and their stimuli-responsive capabilities are overviewed in this paper, including the discussion of shape-memory materials, metamaterials, and self-healing materials and their responses to thermal, pH, moisture, light, magnetic and electrical exposures. Potential applications of such systems have been explored to include advancements in health monitoring, electrical devices, deployable structures, soft robotics and tuneable metamaterials

Interfacial Engineering of Hydrogels Toward Functional Soft Materials

Functional hydrogels engineering is currently transitioning from tuning the global structure and composition of hydrogel networks to focusing on the hydrogel interface. While there are several strategies aimed at fine-tuning the inner network properties, they often lead to compromises in hydrogel bulk properties, and frequently yield hydrogels with amorphous and homogeneous isotropic structure, which are inadequate to meet the functional requirements for advanced applications such as bioelectronics, tissue engineering, soft robotics, adhesion, and actuation. The last few years have seen transformative advances in engineering the soft and hydrated interface of hydrogels, both in academic research and in commercial products. Hydrogels with rational design of multiscale architecture, structural complexity and spatial heterogeneity are fabricated via interfacial engineering. Engineered surface chemistry and architecture has expanded their opportunities in numerous applications, which were previously unattainable with conventional homogeneous bulk hydrogels. However, the field of hydrogel interfacial engineering is still in its infancy and faces challenges including limited functionality and the need to better control various aspects of hydrogel architecture such as length scale, complexity and ambient stability. This thesis aims to address these challenges by presenting a set of fabrication strategies which are facile, universal, and operate under mild reaction conditions, while constructing robust hydrogel interfaces with precise control over architecture and structure across multiple length scales. Through the interfacial precipitation polymerization of two specific water‐soluble monomers that become insoluble during polymerization, a hybrid bilayer hydrogel system was formed, establishing a durable interface between the film and hydrogel. This hierarchical structure offers functionalities akin to human skin, including water loss protection, and tactile, temperature and pressure sensing. Furthermore, this promising synthetic methodology was successfully extent to one monomer in which its polymer is responsive to heat, resulting in the development of robust, tunable, and fast-response hydrogel actuators capable of functioning in diverse environments. Additionally, interfacial precipitation-driven adhesion strategies were developed to enhance the interfacial adhesion of hydrogels to other relatively rigid substrates. Nanoparticle adhesives were designed for hydrogel adhesion through topological entanglement and other noncovalent bonding mechanisms, including metal coordination and hydrogen bonding

Novel 3D bioprinting of biomaterials : application of statistical modeling & machine learning

3D bioprinting, a versatile biofabrication technique, has been widely used in various biomedical research fields. Statistical modeling and machine learning are powerful tools that can expedite the development of pharmaceutical and biomedical research. Within the scope of this dissertation, we applied statistical modeling and machine learning to different fields of bioprinting research. In Chapter 1, we reviewed the latest accomplishments in 3D printed drug delivery devices as well as the major challenges and future perspectives for additive manufacturing-enabled dosage forms and drug delivery systems. In Chapter 2, we provided a comprehensive analysis of 3D bioprinting process parameters that affect bioink printability and cell performance. We further analyzed how these parameters could be tailored to achieve the optimal printing resolution and cell performance. In Chapter 3, a combination of emulsion evaporation and extrusion-based bioprinting technique was employed to formulate polymeric microparticles. We also developed a systemic approach to assess the formulation factor significance and predict drug loading efficiency using comprehensive statistical analysis and machine learning modeling. In Chapter 4, we developed a stepwise approach to evaluate hydrogel printability qualitatively and quantitatively and employed machine learning modelling to predict ink printability. This systemic methodology demonstrates great promises in designing and predicting the properties of newly developed bioinks, expanding the potential of machine learning in biomedical fields. In Chapter 5, we performed the first global bibliometric analysis of the literature on bacteria-mediated cancer therapy from 2012 to 2021. This study provided critical insights into the historical development of this field from 2012 to 2021, which will be helpful for scientists to conduct further investigation into bacteria-mediated cancer therapy. In Appendix A, we provided an overview of the primary routes of bacteria administration for cancer treatment and discussed the advantages as well as limitations of each route. We also highlighted the application prospect of 3D bioprinting in cancer bacteriotherapy, which represents a new paradigm for personalized cancer treatment.  Pharmaceutical Science

Liquid crystals in micron-scale droplets, shells and fibers

peer reviewedThe extraordinary responsiveness and large diversity of self-assembled structures of liquid crystals are well documented and they have been extensively used in devices like displays. For long, this application route strongly influenced academic research, which frequently focused on the performance of liquid crystals in display-like geometries, typically between flat, rigid substrates of glass or similar solids. Today a new trend is clearly visible, where liquid crystals confined within curved, often soft and flexible, interfaces are in focus. Innovation in microfluidic technology has opened for high-throughput production of liquid crystal droplets or shells with exquisite monodispersity, and modern characterization methods allow detailed analysis of complex director arrangements. The introduction of electrospinning in liquid crystal research has enabled encapsulation in optically transparent polymeric cylinders with very small radius, allowing studies of confinement effects that were not easily accessible before. It also opened the prospect of functionalizing textile fibers with liquid crystals in the core, triggering activities that target wearable devices with true textile form factor for seamless integration in clothing. Together, these developments have brought issues center stage that might previously have been considered esoteric, like the interaction of topological defects on spherical surfaces, saddle-splay curvature-induced spontaneous chiral symmetry breaking, or the non-trivial shape changes of curved liquid crystal elastomers with non-uniform director fields that undergo a phase transition to an isotropic state. The new research thrusts are motivated equally by the intriguing soft matter physics showcased by liquid crystals in these unconventional geometries, and by the many novel application opportunities that arise when we can reproducibly manufacture these systems on a commercial scale. This review attempts to summarize the current understanding of liquid crystals in spherical and cylindrical geometry, the state of the art of producing such samples, as well as the perspectives for innovative applications that have been put forward.R-AGR-0505 - IRP15 - UNIQUE (20150401-20180331) - LAGERWALL Ja

Electrospun Nanofibers for Biomedical Applications

Electrospinning is a versatile and effective technique widely used to manufacture nanofibrous structures from a diversity of materials (synthetic, natural or inorganic). The electrospun nanofibrous meshes’ composition, morphology, porosity, and surface functionality support the development of advanced solutions for many biomedical applications. The Special Issue on “Electrospun Nanofibers for Biomedical Applications” assembles a set of original and highly-innovative contributions showcasing advanced devices and therapies based on or involving electrospun meshes. It comprises 13 original research papers covering topics that span from biomaterial scaffolds’ structure and functionalization, nanocomposites, antibacterial nanofibrous systems, wound dressings, monitoring devices, electrical stimulation, bone tissue engineering to first-in-human clinical trials. This publication also includes four review papers focused on drug delivery and tissue engineering applications

Sensitively Humidity-Driven Actuator Based on Photopolymerizable PEG-DA Films

Hydrogels such as poly(ethylene glycol) diacrylate are a class of cross-linked polymers that have the ability to absorb water and change volume. Here, a humidity responsiveness of hydrogel film fabricated by the photopolymerization of poly(ethylene glycol) diacrylate (PEG-DA) monomer is reported. This kind of film could be driven by a small humidity gradient, thus spontaneous deformation and motion can be achieved by placing the film onto a moist filter paper. The influence factors of humidity response sensitivity such as the exposure time and number-average molecular weight of PEG-DA monomer used during the fabrication are investigated. Under different relative humidity, the film displays different degrees of pink color and the intensities of fluorescence under 365 nm illumination are also different, which renders the film to be used as a &quot;humidity test strip.&quot; A humidity-driven walking device is fabricated and the walking velocity is about 3 mm min(-1) under the actuating water vapor. Vapor of volatile polar solvents could also drive the actuator to achieve fast deformation and shows the variety of the film responsivity.</p