3D Printing - To print or not to print? Aspects to consider before adoption - A supply chain perspective

3D printing is believed by many to be the next industrial revolution. The technology is already deployed in production. However, supply chain literature is still in its infancy regarding this topic, despite 3D printings radical impact on supply chains. A framework has been developed to assess various aspects that need to be considered when deploying such technology as part of the production process. Literature has been drawn from cross-discipline (e.g. social sciences, engineering, and business). The challenge for businesses will be whether to incur the cost impact today or the opportunity cost of tomorrow if 3D printing is not adopted

3D printing and the third mission: The university in the materialization of intellectual capital

The production, diffusion and preservation of knowledge are the main goals of universities, which are critical nodes for mediating intellectual capital. In recent years, 3D printing (additive manufacturing) technologies are emerging as a possible disruptive or transformative force in the knowledge economy and by extension the material economy as consumers are given the affordance of materializing information into real-world objects. To understand the role universities will play in this potential convergence of the material and knowledge economies, this paper surveys current levels of involvement of tertiary institutions in 3D printing. The paper projects how the materialization of data will affect a range of social dynamics for creators-cum-consumers at different scales: community, region and nation-state and applies case studies to the multilevel perspective (MLP) framework. Studies are considered in three empirical cases: Berlin in Germany, Lancashire in the United Kingdom, and the United States. The research indicates that the National Additive Manufacturing Innovation Institute (NAMII) \u27America Makes\u27 Program is a top-down knowledge dissemination program for 3D printing. In contrast, the UK Lancaster University Product Development Unit (LPDU) is a 3D-printing value-network, which has developed organically over a decade of operation. Fablab Berlin is a local initiative loosely coupled with industry and tertiary education providers. The paper proposes a future-oriented conceptual framework to capture a variety of present-day university engagements with additive manufacturing in terms of intellectual capital

Fluidic automation of nitrate and nitrite bioassays in whole blood by dissolvable-film based centrifugo-pneumatic actuation

This paper demonstrates the full centrifugal microfluidic integration and automation of all liquid handling steps of a 7-step fluorescence-linked immunosorbent assay (FLISA) for quantifying nitrate and nitrite levels in whole blood within about 15 min. The assay protocol encompasses the extraction of metered plasma, the controlled release of sample and reagents (enzymes, co-factors and fluorescent labels), and incubation and detection steps. Flow control is implemented by a rotationally actuated dissolvable film (DF) valving scheme. In the valves, the burst pressure is primarily determined by the radial position, geometry and volume of the valve chamber and its inlet channel and can thus be individually tuned over an extraordinarily wide range of equivalent spin rates between 1,000 RPM and 5,500 RPM. Furthermore, the vapour barrier properties of the DF valves are investigated in this paper in order to further show the potential for commercially relevant on-board storage of liquid reagents during shelf-life of bioanalytical, ready-to-use discs

Fabricating electrodes for amperometric detection in hybrid paper/polymer lab-on-a-chip devices

We present a novel, low-resource fabrication and assembly method for creating disposable amperometric detectors in hybrid paper-polymer devices. Currently, mere paper-based microfluidics is far from being able to achieve the same level of process control and integration as state-of-the-art microfluidic devices made of polymers. To overcome this limitation, in this work both substrate types are synergistically combined through a hybrid, multi-component/multi-material system assembly. Using established inkjet wax printing, we transform the paper into a profoundly hydrophobic substrate in order to create carbon electrodes which are simply patterned from carbon inks via custom made adhesive stencils. By virtue of the compressibility of the paper substrate, the resulting electrodeon- paper hybrids can be directly embedded in conventional, 3D polymeric devices by bonding through an adhesive layer. This manufacturing scheme can be easily recreated with readily available off-the-shelf equipment, and is extremely cost-efficient and rapid with turn-around times of only a few hours

Infrared controlled waxes for liquid handling and storage on a CD-microfluidic platform

A novel active valving technique, whereby paraffin wax plugs in microchannels on a centrifugal microfluidic platform are actuated using focused infrared (IR) radiation is demonstrated in this report. Microchannels were simultaneously or sequentially opened using a stationary IR source by forming wax plugs with similar or differing melting points. The presented wax plugs offer key advantages over current active valving techniques, including a less involved fabrication procedure, a simpler actuation process, and the ability to multiplex experiment with active valves. In addition, a new technique for automated liquid reagent storage and release on the microfluidic disc platform, based on the formation and removal of a wax layer, is demonstrated. Overall, the techniques presented in this report offer novel methods for liquid handling, separation, and storage on the centrifugal microfluidic disc platform.close272

An overview of the suitability of hydrogel-forming polymers for extrusion-based 3D-printing

This review evaluates hydrogel-forming polymers that are suitable for soft tissue engineering with a focus on materials that can be fabricated using additive manufacturing (3D-printing). An overview of the specific material requirements for hydrogel-based tissue engineering constructs is presented. This is followed by an explanation of the various hydrogel-forming polymer classes that includes a detailed examination of material properties that are critical for extrusion printing. Specifically, mechanisms for hydrogel formation, degradation, and biological response, activity and compatibility are explored. A discussion of extrusion printing strategies for printable hydrogel-forming polymers is then presented in conjunction with a list of considerations to guide future tissue engineering developments

3D printing of tough hydrogel composites with spatially varying materials properties

Biofabrication is the process of transforming materials into systems that reproduce biological structure and function. Previous attempts to create biomimetic systems have often used single materials shaped into limited configurations that do not mimic the heterogeneous structure and properties of many biological tissues. The identification of new bio-inspired materials alongside the development of appropriate fabrication techniques is the key to overcoming the challenge of replicating the functional gradients of these heterogeneous tissues. This paper presents a new extrusion-based gradient printing system that utilizes custom software to control the rates at which two inks are dispensed through a mixing nozzle. The printer was used to fabricate a range of composite materials containing varying blends of a tough alginate/poly(acrylamide) ionic covalent entanglement hydrogel and an acrylated urethane based UV-curable adhesive material. The hard adhesive material acted as particulate reinforcement within the matrix of composites printed with a large hydrogel volume fraction. The composite materials were characterized mechanically and their performance could be modeled with standard composite theory. The platform of a 3D printer allowed these composite materials to be fabricated directly with a smooth and continuous gradient of modulus between the soft hydrogel and harder acrylated urethane material, which may be useful in the development of bio-inspired structures such as artificial tendons

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

Grapene-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 nucleation centre for the crystallisation of the polymer resulting in polymer-functionalised nanosheets. During polymerisation, the graphene oxide was also reduced to conducting graphene. The resulting graphene/polymer composites were comparable to composites prepared by blending previously highly chemically reduced graphene into polycaprolactone, and they could be easily dispersed in a number of solvents or melt extruded for further processing. These three-dimensional melt extruded materials showed excellent biocompatibility and are promising substrates for tissue engineering scaffolds

Near field electroprinted hydrogel arrays for electrochemical sensing

We report on a new technique known as Near Field Electroprinting (NFEP) to fabricate a gelatin hydrogel based array for use as an electrochemical sensor. Using this technique, an array of gelatin fibers one micron in diameter and spaced approximately 100 micron apart, was patterned and subsequently cross-linked. To validate its use as a sensor, the ends of the array were coated in gold to provide electrical connections and a CV was performed using a ferricyanide redox couple. This work opens up the development of printed hydrogel biosensors exploiting the biocompatibility of hydrogel materials

A simple technique for development of fibres with programmable microsphere concentration gradients for local protein delivery

Alginate has been a biologically viable option for controlled local delivery of bioactive molecules in vitro and in vivo. Specific bioactive molecule release profiles are achieved often by controlling polymer composition/concentration, which also determines the modulus of hydrogels. This largely limits alginate-mediated bioactive molecule delivery to single-factors of uniform concentration applications, rather than applications that may require (multiple) bioactive molecules delivered at a concentration gradient for chemotactic purposes. Here we report a two-phase PLGA/alginate delivery system composed of protein-laden poly-d,l-lactic-co-glycolic acid (PLGA) microspheres wet-spun into alginate fibres. Fluorescein isothiocyanate-conjugated bovine serum albumin (FITC-BSA) was used as a model protein and the developed structures were characterized. The fabrication system devised was shown to produce wet-spun fibres with a protein concentration gradient (G-Alg/PLGA fibre). The two-phase delivery matrices display retarded FITC-BSA release in both initial and late stages compared to release from the PLGA microspheres or alginate fibre alone. In addition, incorporation of higher concentrations of protein-loaded PLGA microspheres increased protein release compared to the fibres with lower concentrations of BSA-loaded microspheres. The programmable microsphere concentration gradient fibre methodology presented here may enable development of novel alginate scaffolds with the ability to guide tissue regeneration through tightly-controlled release of one or more proteins in highly defined spatio-temporal configurations