3D Bioplotter Research Papers

Displaying all papers about Electrical Conductivity (18 results)

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.

3D printing of free-standing and flexible nitrogen doped graphene/ polyaniline electrode for electrochemical energy storage

Chemical Physics Letters 2019 Volume 728, August 2019, Pages 6-13

Flexible graphene film can be quickly realized by three-dimensional printing (3D printing), which has the potential in functional electronic devices. With a trace of cobalt ions as crosslinker, the graphene oxide sol can be converted into 3D printed ink, overcoming the disadvantage of insufficient viscosity of pure graphene oxide ink. The various graphene architectures were successfully obtained by 3D printing, moreover, graphene/polyaniline composites were obtained by electropolymerization. The specific capacitance of graphene/polyaniline electrode achieved up to 238 F/g at the current density of 0.5 A/g, which was much higher than that of graphene electrode (35 F/g).

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

Polymers for Advanced Technologies 2019

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…

A method to deliver patterned electrical impulses to Schwann cells cultured on an artificial axon

Neural Regeneration Research 2019 Volume 14, Issue 6, Pages 1052-1059

Information from the brain travels back and forth along peripheral nerves in the form of electrical impulses generated by neurons and these impulses have repetitive patterns. Schwann cells in peripheral nerves receive molecular signals from axons to coordinate the process of myelination. There is evidence, however, that non-molecular signals play an important role in myelination in the form of patterned electrical impulses generated by neuronal activity. The role of patterned electrical impulses has been investigated in the literature using co-cultures of neurons and myelinating cells. The co-culturing method, however, prevents the uncoupling of the direct effect of patterned electrical impulses…

Defect-engineered reduced graphene oxide sheets with high electric conductivity and controlled thermal conductivity for soft and flexible wearable thermoelectric generators

Nano Energy 2018 Volume 54, Pages 163-174

The direct use of graphene for potential thermoelectric material requires the opening of its bandgap without loss of its high electric conductivity. We herein demonstrate a synchronous reduction and assembly strategy to fabricate large-area reduced graphene oxide films with high electric conductivity and optimized low thermal conductivity assembly. The reduced graphene oxide films have a high electric conductivity and low thermal conductivity, which results from high longitudinal carrier mobility of the lattice domains as well as the enhanced scattering of phonons in the defects and their boundary that substantially reduces the mean phonon free path and the thermal conductivity. Flexible…

Voltaglue Bioadhesives Energized with Interdigitated 3D‐Graphene Electrodes

Advanced Healthcare Materials 2018 Volume 7, Issue 21, Article 1800538

Soft tissue fixation of implant and bioelectrodes relies on mechanical means (e.g., sutures, staples, and screws), with associated complications of tissue perforation, scarring, and interfacial stress concentrations. Adhesive bioelectrodes address these shortcomings with voltage cured carbene‐based bioadhesives, locally energized through graphene interdigitated electrodes. Electrorheometry and adhesion structure activity relationships are explored with respect to voltage and electrolyte on bioelectrodes synthesized from graphene 3D‐printed onto resorbable polyester substrates. Adhesive leachates effects on in vitro metabolism and human‐derived platelet‐rich plasma response serves to qualitatively assess biological response. The voltage activated bioadhesives are found to have gelation times of 60 s or less…

Printed, Flexible pH Sensor Hydrogels for Wet Environments

Advanced Materials Technologies 2018 Volume 3, Issue 11, Article 1800137

Current sensors for monitoring environmental signals, such as pH, are often made from rigid materials that are incompatible with soft biological tissues. The high stiffness of such materials sets practical limitations on the in situ utilization of sensors under biological conditions. This article describes a soft yet robust hydrogel‐based pH sensor that can be 3D printed. The pH‐sensitive poly(3,4‐ethylenedioxythiophene) is combined with hydrophilic polyurethane to create novel printable inks with favorable biomechanical properties. These inks are employed to fabricate highly flexible pH sensors that linearly respond to pH in wet environments. The pH sensitive hydrogels can undergo extreme deformations including…

Conductive Composite Fibres from Reduced Graphene Oxide and Polypyrrole Nanoparticles

Journal of Materials Chemistry B 2016 Volume 4, Issue 6, Pages 1142-1179

Continuous composite fibres composed of polypyrrole (PPy) nanoparticles and reduced graphene oxide (rGO) at different mass ratios were fabricated using a single step wet-spinning approach. The electrical conductivity of the composite fibres increased significantly with the addition of rGO. The mechanical properties of the composite fibres also improved by the addition of rGO sheets compared to fibres containing only PPy. The ultimate tensile strength of the fibres increased with the proportion of rGO mass present. The elongation at break was greatest for the composite fibre containing equal mass ratios of PPy nanoparticles and rGO sheets. L929 fibroblasts seeded onto fibres…

Multi‐and mixed 3D‐printing of graphene‐hydroxyapatite hybrid materials for complex tissue engineering

Journal of Biomedical Materials Research Part A 2016 Volume 105, Issue 1, Pages 274–283

With the emergence of 3D-printing (3DP) as a vital tool in tissue engineering and medicine, there is an ever growing need to develop new biomaterials that can be 3D-printed and also emulate the compositional, structural, and functional complexities of human tissues and organs. In this work, we probe the 3D-printable biomaterials spectrum by combining two recently established functional 3D-printable particle-laden biomaterial inks: one that contains hydroxyapatite microspheres (Hyperelastic Bone, HB) and another that contains graphene nanoflakes (3D-Graphene, 3DG). We demonstrate that not only can these distinct, osteogenic and neurogenic inks be co-3D-printed to create complex, multi-material constructs, but that composite…

Three Dimensional Printing of High-Content Graphene Scaffolds for Electronic and Biomedical Applications

ACS Nano 2015 Volume 9, Issue 4, Pages 4636–4648

The exceptional properties of graphene enable applications in electronics, optoelectronics, energy storage, and structural composites. Here we demonstrate a 3D printable graphene (3DG) composite consisting of majority graphene and minority polylactide-co-glycolide, a biocompatible elastomer, 3D-printed from a liquid ink. This ink can be utilized under ambient conditions via extrusion-based 3D printing to create graphene structures with features as small as 100 μm composed of as few as two layers (10 cm thick object). The resulting 3DG material is mechanically robust and flexible while retaining electrical conductivities greater than 800 S/m, an order of magnitude increase over previously reported 3D-printed carbon…

Fabrication of Force Sensor Circuits on Wearable Conductive Textiles

Procedia Technology 2015 Volume 20, Pages 263–269

This paper discusses design and fabrication processes in the development of a wearable and flexible conductive resistive sensor. The design and development of the sensor involve the use of Sn-Ag-Cu (SAC)plated Nylon fabric, precisionfused deposition modeling(FDM) using silicone and petrolatum for etch-resistant masks using the EnvisionTEC GmbH Bioplotter, and wet etching using Chromium, Ammonium Persulphate, and Salt-Vinegar etching solutions. Preliminary testing with other mask types, development processes, and sensor design approaches for various applications are discussed.

From nanoparticles to fibres: effect of dispersion composition on fibre properties

Journal of Nanoparticle Research 2015 Volume 17, Issue 237, Pages 237ff

A polyvinyl alcohol (PVA)-stabilized polypyrrole nanodispersion has been optimised for conductivity and processability by decreasing the quantity of PVA before and after synthesis. A reduction of PVA before synthesis leads to the formation of particles with a slight increase in dry particle diameter (51 ± 6 to 63 ± 3 nm), and conversely a reduced hydrodynamic diameter. Conductivity of the dried nanoparticle films was not measureable after a reduction of PVA prior to synthesis. Using filtration of particles after synthesis, PVA content was sufficiently reduced to achieve dried thin film conductivity of 2 S cm−1, while the electroactivity of the…

A bio-friendly, green route to processable, biocompatible graphene/polymer composites

RSC Advances 2015 Volume 5, Issue 56, 45284-45290

Graphene-based polymer composites are a very promising class of compounds for tissue engineering scaffolds. However, in general the methods of synthesis are environmentally hazardous and residual toxic materials can affect the biocompatibility significantly. In this paper a simple, scalable, environmentally-friendly, microwave-assisted synthesis is described that results in conducting graphene/polycaprolactone composites that retain the processability and biocompatibility of the pristine polymer without introducing possibly hazardous reducing agents. Composites of polycaprolactone and graphene oxide were synthesised in a single step by the ring-opening polymerisation of ε-caprolactone in the presence of dispersed graphene oxide nanosheets under microwave irradiation. The graphene oxide provides a…

Metallic Architectures from 3D‐Printed Powder‐Based Liquid Inks

Advanced Functional Materials 2015 Volume 25, Issue 45, Pages 6985–6995

A new method for complex metallic architecture fabrication is presented, through synthesis and 3D-printing of a new class of 3D-inks into green-body structures followed by thermochemical transformation into sintered metallic counterparts. Small and large volumes of metal-oxide, metal, and metal compound 3D-printable inks are synthesized through simple mixing of solvent, powder, and the biomedical elastomer, polylactic-co-glycolic acid (PLGA). These inks can be 3D-printed under ambient conditions via simple extrusion at speeds upwards of 150 mm s–1 into millimeter- and centimeter-scale thin, thick, high aspect ratio, hollow and enclosed, and multi-material architectures. The resulting 3D-printed green-bodies can be handled immediately, are…

Graphene oxide dispersions: tuning rheology to enable fabrication

Materials Horizons 2014 Volume 1, Issue 3, Pages 326-331

Here, we show that graphene oxide (GO) dispersions exhibit unique viscoelastic properties, making them a new class of soft materials. The fundamental insights accrued here provide the basis for the development of fabrication protocols for these two-dimensional soft materials, in a diverse array of processing techniques.

3D Micro‐Extrusion of Graphene‐based Active Electrodes: Towards High‐Rate AC Line Filtering Performance Electrochemical Capacitors

Advanced Functional Materials 2014 Volume 24, Issue 29, Pages 4706–4716

A facile one-step printing process by 3D micro-extrusion affording binder-free thermally reduced graphene oxide (TRGO) based electrochemical capacitors (ECs) that display high-rate performance is presented. Key intermediates are binder-free TRGO dispersion printing inks with concentrations up to 15 g L−1. This versatile printing technique enables easy fabrication of EC electrodes, useful in both aqueous and non-aqueous electrolyte systems. The as-prepared TRGO material with high specific surface area (SSA) of 593 m2 g−1 and good electrical conductivity of ≈16 S cm−1 exhibits impressive charge storage performances. At 100 and 120 Hz, ECs fabricated with TRGO show time constants of 2.5 ms…

Biocompatibility analysis of an electrically-activated silver-based antibacterial surface system for medical device applications

Journal of Materials Science: Materials in Medicine 2013 Volume 24, Issue 3, Pages 755-760

The costs associated with the treatment of medical device and surgical site infections are a major cause of concern in the global healthcare system. To prevent transmission of such infections, a prophylactic surface system that provides protracted release of antibacterial silver ions using low intensity direct electric current (LIDC; 28 μA system current at 6 V) activation has been recently developed. To ensure the safety for future in vivo studies and potential clinical applications, this study assessed the biocompatibility of the LIDC-activated interdigitated silver electrodes-based surface system; in vitro toxicity to human epidermal keratinocytes, human dermal fibroblasts, and normal human…

Emulsifier-Free Graphene Dispersions with High Graphene Content for Printed Electronics and Freestanding Graphene Films

Advanced Functional Materials 2012 Volume 22, Issue 6, Pages 1136-1144

A novel and highly versatile synthetic route for the production of functionalized graphene dispersions in water, acetone, and isopropanol (IPA), which exhibit long-term stability and are easy to scale up, is reported. Both graphene functionalization (wherein the oxygen content can be varied from 4 to 16 wt%) and dispersion are achieved by the thermal reduction of graphite oxide, followed by a high-pressure homogenization (HPH) process. For the first time, binders, dispersing agents, and reducing agents are not required to produce either dilute or highly concentrated dispersions of single graphene sheets with a graphene content of up to 15 g L−1….