3D Bioplotter Research Papers

Displaying all papers by A. Kaynak (14 results)

Topology-Optimized 4D Printing of a Soft Actuator

Acta Mechanica Solida Sinica 2020 Volume 33, Pages 418–430

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….

Double dynamic cellulose nanocomposite hydrogels with environmentally adaptive self-healing and pH-tuning properties

Cellulose 2020 Volume 27, Pages 1407–1422

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…

Fabrication of a conductive composite structure with enhanced stretchability using direct-write 3D printing

Materials Research Express 2019 Volume 6, Number 8, Article 085319

High stretchability and mechanical stability are the key properties of a conductive polymer composite structure. In this work, an anisotropic composite is fabricated by wet 3D printing of epoxy crosslinked chitosan/carbon microtubes. The carbon microtubes were synthesized through a high temperature carbonization of chemically purified cellulose fibres. After the chemical treatment and high temperature carbonization, the removal amorphous substrates from the core of cotton fibres results in the formation of a tubular structure. Here, chitosan which is an abundant natural polymer was used as the composite matrix. It was found that the epoxy crosslinking increases the stretchability of composite filaments.

System identification and robust tracking of a 3D printed soft actuator

Smart Materials and Structures 2019 Volume 28, Article 075025

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…

Wet 3‐D printing of epoxy cross‐linked chitosan/carbon microtube composite

Polymers for Advanced Technologies 2019 Volume 30, Issue 7, Pages 1732-1737

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…

Nanogrooved carbon microtubes for wet 3D printing of conductive composite structures

Polymer International 2019 Volume 68, Issue 5, Pages 922-928

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…

Bending Control of a 3D Printed Polyelectrolyte Soft Actuator with Uncertain Model

Sensors and Actuators A: Physical 2019 Volume 288, Pages 134-143

Introduction of 3-dimensional (3D) printing in fabrication and increasing applications of intriguing products in soft robotics have led to studies on controllable 3D printed soft actuators. Therefore, a demand for a precise and computationally efficient model for bending control of the 3D printed soft actuators has arisen. This study initially used a grey box strategy for dynamic modeling of a 3D printed soft actuator which undergoes large bending deformations. Yet, the primary model estimated results deviated from experimental results due to uncertainties such as hysteresis and time varying characteristics of the soft actuator in presence of electric field. Thus, a…

Rigid elements dynamics modeling of a 3D printed soft actuator

Smart Materials and Structures 2019 Volume 28, Issue 2, Article 025003

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…

3D printed soft parallel actuator

Smart Materials and Structures 2018 Volume 27, Number 4, Article 045019

This paper presents a 3-dimensional (3D) printed soft parallel contactless actuator for the first time. The actuator involves an electro-responsive parallel mechanism made of two segments namely active chain and passive chain both 3D printed. The active chain is attached to the ground from one end and constitutes two actuator links made of responsive hydrogel. The passive chain, on the other hand, is attached to the active chain from one end and consists of two rigid links made of polymer. The actuator links are printed using an extrusion-based 3D-Bioplotter with polyelectrolyte hydrogel as printer ink. The rigid links are also…

Polyelectrolyte Soft Actuators: 3D Printed Chitosan and Cast Gelatin

3D Printing and Additive Manufacturing 2018 Volume 5, Issue 2, Pages 138-150

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…

Surface nanogrooving of carbon microtubes

Scientific Reports 2018 Volume 8, Article 9924

Extrusion processing of carbon tubes can be problematic due to their poor interfacial interactions with polymeric matrices. Surface chemical modification of carbon tubes can be utilized to create bonding sites to form networks with polymer chains. However, chemical reactions resulting in intermolecular primary bonding limit processability of extrudate, since they cause unstable rheological behaviour, and thus decrease the stock holding time, which is determinative in extrusion. This study presents a method for the synthesis of carbon microtubes with physically modified surface area to improve the filler and matrix interfacial interactions. The key concept is the formation of a nanogrooved topography,…

Iterative feedback bio-printingderived cell-laden hydrogel scaffolds with optimal geometrical fidelity and cellular controllability

Scientific Reports 2018 Volume 8, Article number: 2802

For three-dimensional bio-printed cell-laden hydrogel tissue constructs, the well-designed internal porous geometry is tailored to obtain the desired structural and cellular properties. However, significant differences often exist between the designed and as-printed scaffolds because of the inherent characteristics of hydrogels and cells. In this study, an iterative feedback bio-printing (IFBP) approach based on optical coherence tomography (OCT) for the fabrication of cell-laden hydrogel scaffolds with optimal geometrical fidelity and cellular controllability was proposed. A custom-made swept-source OCT (SS-OCT) system was applied to characterize the printed scaffolds quantitatively. Based on the obtained empirical linear formula from the first experimental feedback loop,…

Development and Analysis of a 3D Printed Hydrogel Soft Actuator

Sensors and Actuators A 2017 Volume 265, Pages 94–101

Polyelectrolyte hydrogels produce mechanical motion in response to electrical stimulus making them a good candidate for implementation of soft actuators. However, their customary fabrication process has thus far hindered their applicability in a broad range of controlled folding behaviours. This paper employs the 3D printing technology does the development of polyelectrolyte hydrogel soft actuators. A 3D printed soft hydrogel actuator with contactless electrodes is presented for the first time. Initially chitosan as a candidate of polyelectrolytes which possess both printability and stimuli responsive is opted for ink preparation of 3D printing. The printing parameters are optimised for fabrication of desired…

3D Printing of a Photo-thermal Self-folding Actuator

The International Conference on Design and Technology 2017 Pages 15-22

The demand for rapid and accurate fabrication of light-weight, biocompatible, and soft actuators in soft robotics has perused researchers to design and fabricate such products by rapid manufacturing techniques. The self-folding origami structure is a type of soft actuator that has applications in micro electro mechanical systems, soft electronics, and biomedical devices. 3-dimentional (3D) printing is a current manufacturing process that can be used for fabrication of involute soft self-folding products by means of shape memory polymer materials. This paper presents, for the first time, a method for developing a photo thermal self-folding soft actuator using a 3D bioplotter. Easily…