3D Bioplotter Research Papers

The development of the effective 3D printing strategy for diverse functional monomers is still challenging. Moreover, the conventional 3D printing hydrogels are usually soft and fragile due to the lack of an energy dissipation mechanism. Herein, a microsphere mediating ink preparation strategy is developed to provide tailored rheological behavior for various monomer direct ink writings. The chitosan microspheres are used as an exemplary material due to their tunable swelling ratio under the acid-drived electrostatic repulsion of the protonated amino groups. The rheological behaviors of the swollen chitosan microsphere (SCM) are independent on the monomer types, and various functional secondary polymers…

Dielectric elastomer transducers (DET) are promising candidates for electrically-driven soft robotics. However, the high viscosity and low yield stress of DET formulations prohibit 3D printing, the most common manufacturing method for designer soft actuators. DET inks optimized for direct ink writing (DIW) produce elastomers with high stiffness and mechanical losses, diminishing the utility of DET actuators. To address the antagonistic nature of processing and performance constraints, principles of capillary suspensions are used to engineer DIW DET inks. By blending two immiscible polysiloxane liquids with a filler, a capillary ink suspension is obtained, in which the ink rheology can be tuned…

Combined photothermal-hygroscopic effects enable novel materials actuation strategies based on renewable and sustainable energy sources such as sunlight. Plasmonic nanoparticles have gained considerable interest as photothermal agents, however, the employment in sunlight-driven photothermal-hygroscopic actuators is still bounded, mainly due to the limited absorbance once integrated into nanocomposite actuators and the restricted plasmonic peaks amplitude (compared to the solar spectrum). Herein, the design and fabrication of an AgNPs-based plasmonic photothermal-hygroscopic actuator integrated with printed cellulose tracks are reported (bioinspired to Geraniaceae seeds structures). The nanocomposite is actuated by sunlight power density (i.e., 1 Sun = 100 mW cm−2). The plasmonic AgNPs…

Geraniaceae seeds represent a role model in soft robotics thanks to their ability to move autonomously across and into the soil driven by humidity changes. The secret behind their mobility and adaptivity is embodied in the hierarchical structures and anatomical features of the biological hygroscopic tissues, geometrically designed to be selectively responsive to environmental humidity. Following a bioinspired approach, the internal structure and biomechanics of Pelargonium appendiculatum (L.f.) Willd seeds are investigated to develop a model for the design of a soft robot. The authors exploit the re-shaping ability of 4D printed materials to fabricate a seed-like soft robot, according…

Photoresponsive soft liquid crystalline elastomers (LCEs) transform light’s energy into dynamic shape changes and are considered promising candidates for production of soft robotic or muscle-like devices. 3D printing allows access to elaborated geometries as well as control of the photoactuated movements; however, this development is still in its infancy and only a limited choice of LCE is yet available. Herein, we propose to introduce biocompatible and sustainable cellulose nanocrystals (CNC) into an LCE in order to facilitate the printing process by direct ink writing (DIW) and to benefit from the anisotropic mechanical properties resulting from the extrusion-induced alignment of such…

The capacity for a soft material to combine remote sensing and remote actuation is highly desirable for many applications in soft robotics and wearable technologies. This work presents a silicone elastomer with a suspension of a small weight fraction of ferromagnetic nickel nanorods, which is capable of both sensing deformation and altering stiffness in the presence of an external magnetic field. Cylinders composed of silicone elastomer and 1% by weight nickel nanorods experience large increases in compressive modulus when exposed to an external magnetic field. Incremental compressions totaling 600 g of force applied to the same silicone–nanorod composites increase the…

3D printing technologies allow control over the alignment of building blocks in synthetic materials, but compositional changes often require complex multimaterial printing steps. Here, 3D printable materials showing locally tunable mechanical properties are produced in a single printing step of Direct Ink Writing. These new inks consist of a polymer matrix bearing biocompatible photoreactive cinnamate derivatives and up to 30 wt% of anisotropic cellulose nanocrystals. The printed materials are mechanically versatile and can undergo further crosslinking upon illumination. When illuminating the material and controlling the irradiation doses, the Young’s moduli can be adjusted between 15 and 75 MPa. Moreover, spatially…

Currently, 3D printing is one of the popular technological production methods, mainly because it offers various options that affect the resulting properties of prints. The aim of the presented work is to manufacture a prosthetic finger with a PIP and DIP joint using multi-material 3D printing, which will allow to mimic the flexion of a physiological finger. The subject of this research and testing is the design of a combination of solid and flexible material for a monolithic finger model, which will allow the required bending in selected areas of the print.

Soft robots and actuators are emerging devices providing more capabilities in the field of robotics. More flexibility and compliance attributing to soft functional materials used in the fabrication of these devices make them ideal for delivering delicate tasks in fragile environments, such as food and biomedical sectors. Yet, the intuitive nonlinearity of soft functional materials and their anisotropic actuation in compliant mechanisms constitute an existent challenge in improving their performance. Topology optimization (TO) along with four-dimensional (4D) printing is a powerful digital tool that can be used to obtain optimal internal architectures for the efficient performance of porous soft actuators.…

Dynamic hydrogels are prepared by either dynamic covalent bonds or supramolecular chemistry. Herein, we develop a dynamic hydrogel by combining both dynamic covalent bonds and supramolecular chemistry that exhibits environmentally adaptive self-healing and pH-tuning properties. To do so, we prepared a gelatin–nanopolysaccharide mixed hydrogel containing pyrogallol/catechol groups and trivalent metal ions. The as-prepared hydrogels are able to heal damage inflicted on them under acidic (pH 3 and 6), neutral (pH 7), and basic (pH 9) environments. The mechanism of healing at acidic and neutral pHs is dominated by coordination bonds between pyrogallol/catechol groups of tannic acid and ferric ions, whilst…

Current three-dimensional (3D) printing allows for the fabrication of controllable 3D printed soft actuators with growing applications in soft robotics, like cell manipulation and drug delivery. Therefore, a precise and computationally efficient control algorithm for robust trajectory tracking of the 3D printed soft actuators has become important. The results of the primary model of the soft actuator deviated from experimental results due to uncertainties such as time-varying characteristics of the actuator. Hence, a second-order type nonsingular terminal sliding mode controller (NTSMC) for robust stabilization and trajectory tracking of the 3D printed actuator is proposed. It is shown via experiments that…

Over the last decays, the use of conductive biopolymer composites has been growing in areas such as biosensors, soft robotics, and wound dressing applications. They are generally soft hydrophilic materials with good elastic recovery and compatible with biological environments. However, their application and removal from the host are still challenging mainly due to poor mechanical strength. This work displays a technique for the fabrication of complex‐shaped conductive structures with improved mechanical strength by wet three‐dimensional (3‐D) printing, which uses a coagulation bath to quickly solidify an epoxy cross‐linked chitosan/carbon microtube composite ink. The fabricated conductive structure demonstrated higher elongation strength…

Recent advances in 3D printing have enabled the fabrication of interesting structures which were not achievable using traditional fabrication approaches. 3D printing of carbon microtube composite inks allows fabrication of conductive structures for practical applications in soft robotics and tissue engineering. However, it is challenging to achieve 3D printed structures from solution‐based composite inks which requires an additional process to solidify the ink. Here, we introduce a wet 3D printing technique which uses a coagulation bath to fabricate carbon microtube composite structures. We show that through facile nanogrooving approach which introduces cavitation and channels on carbon microtubes, enhanced interfacial interactions…

Due to the growing interest in three-dimensional (3D) printed soft actuators, the establishment of an appropriate mathematical model that could effectively predict the actuators’ dynamic behavior has become necessary. This study presents the development of an effective modeling strategy for the dynamic analysis of a 3D printed polyelectrolyte actuator undergoing large bending deformations. The proposed model is composed of two parts, namely electrical and mechanical dynamic models. The electrical model describes the actuator as a gray box model, whereas the mechanical model relates the stored charges to the bending displacement through considering the printed actuator as a discretized system connected…

With increasing utilization of robots in daily tasks, especially in biomedical and environmental monitoring applications, there would be demands for soft, biodegradable, or even edible actuators that provide more versatility than conventional rigid materials (e.g., metals and plastics). Polyelectrolyte hydrogels produce mechanical motion in response to electrical stimulus, making them good candidates for implementation of soft actuators. However, their conventional fabrication process has so far hindered their applicability in a broad range of controlled folding behaviors. A novel application of 3D printing in biodegradable and biocompatible soft robots is presented in this study. It is observed that the contactless electroactive…

Biology uses various cross-linking mechanisms to tailor material properties, and this is inspiring technological efforts to couple independent cross-linking mechanisms to create hydrogels with complex mechanical properties. Here, it is reported that a hydrogel formed from a single polysaccharide can be triggered to reversibly switch cross-linking mechanisms and switch between elastic and viscoelastic properties. Specifically, the pH-responsive self-assembling aminopolysaccharide chitosan is used. Under acidic conditions, chitosan is polycationic and can be electrostatically cross-linked by sodium dodecyl sulfate (SDS) micelles to confer viscoelastic and self-healing properties. Under basic conditions, chitosan becomes neutral, the electrostatic SDS–chitosan interactions are no longer operative, and…

Carrageenan/epoxy amine ionic-covalent entanglement hydrogels were fabricated on a 3D printer. The thermal gel transition behaviour of the biopolymer kappa-carrageenan was exploited to fix the shape of the patterned ink until a covalent polymer network formed by epoxy amine addition chemistry. The printed hydrogels display a work of extension value of 1.4 ± 0.3 MJ m−3.