A combined electrospinning and microestrusion apparatus

Combined electrospinning and microextrusion apparatus, comprising a robotic manipulator (10) provided with a plurality of degrees of freedom, an end effector (20) supported and movable by the robotic manipulator (10), a plurality of extruders (30) housed on the end effector (20), each of the extruders being provided with an interchangeable nozzle (3 1) for the extrusion of at least one material, a working plane (40) configured for the deposition of the extruded material, a pneumatic circuit (120) configured to supply a fluid flow to the extruders (30) for controlling the extrusion of the material, and an electric generator (50) selectively activatable to apply a potential difference between the nozzles (3 1) of the extruders (30) and the working plane (40), whereby the extruders (30) are capable of operating selectively in microextrusion mode with inactive electric generator or in electrospinning mode with active electric generator, in an independent manner from each other

Pectin-Based Scaffolds for Tissue Engineering Applications

Tissue engineering (TE) is an interdisciplinary field that was introduced from the necessity of finding alternative approaches to transplantation for the treatment of damaged and diseased organs or tissues. Unlike the conventional procedures, TE aims at inducing the regeneration of injured tissues through the implantation of customized and functional engineered tissues, built on the so-called ‘scaffolds’. These provide structural support to cells and regulate the process of new tissue formation. The properties of the scaffold are essentials, and they can be controlled by varying the biomaterial formulation and the fabrication technology used to its production. Pectin is emerging as an alternative biomaterial to non-degradable and high-cost petroleum-based biopolymers commonly used in this field. It shows several promising properties including biocompatibility, biodegradability, non-toxicity and gelling capability. Pectin-based formulations can be processed through different fabrication approaches into bidimensional and three-dimensional scaffolds. This chapter aims at highlighting the potentiality in using pectin as biomaterial in the field of tissue engineering. The most representative applications of pectin in preparing scaffolds for wound healing and tissue regeneration are discussed

Physicochemical Characterization of Pectin-Gelatin Biomaterial Formulations for 3D Bioprinting.

AbstractDeveloping biomaterial formulations with specific biochemical characteristics and physical properties suitable for bioprinting of 3D scaffolds is a pivotal challenge in tissue engineering. Therefore, the design of novel bioprintable formulations is a continuously evolving research field. In this work, the authors aim at expanding the library of biomaterial inks by blending two natural biopolymers: pectin and gelatin. Cytocompatible formulations are obtained by combining pectin and gelatin at different ratios and using (3‐glycidyloxypropyl)trimethoxysilane (GPTMS) as single crosslinking agent. It is shown that the developed formulations are all suitable for extrusion‐based 3D bioprinting. Self‐supporting scaffolds with a designed macroporosity and micropores in the bioprinted struts are successfully obtained by combining extrusion‐based bioprinting and freeze‐drying. The presence of gelatin in these formulations allows for the modulation of porosity, of water uptake and of scaffold stiffness in respect to pure pectin scaffolds. Results demonstrate that these new biomaterial formulations, processed with this specific approach, are promising candidates for the fabrication of tissue‐like scaffolds for tissue regeneration

A computational analysis of a novel therapeutic approach combining an advanced medicinal therapeutic device and a fracture fixation assembly for the treatment of osteoporotic fractures: Effects of physiological loading, interface conditions, and fracture fixation materials

: The occurrence of periprosthetic femoral fractures (PFF) has increased in people with osteoporosis due to decreased bone density, poor bone quality, and stress shielding from prosthetic implants. PFF treatment in the elderly is a genuine concern for orthopaedic surgeons as no effective solution currently exists. Therefore, the goal of this study was to determine whether the design of a novel advanced medicinal therapeutic device (AMTD) manufactured from a polymeric blend in combination with a fracture fixation plate in the femur is capable of withstanding physiological loads without failure during the bone regenerative process. This was achieved by developing a finite element (FE) model of the AMTD together with a fracture fixation assembly, and a femur with an implanted femoral stem. The response of both normal and osteoporotic bone was investigated by implementing their respective material properties in the model. Physiological loading simulating the peak load during standing, walking, and stair climbing was investigated. The results showed that the fixation assembly was the prime load bearing component for this configuration of devices. Within the fixation assembly, the bone screws were found to have the highest stresses in the fixation assembly for all the loading conditions. Whereas the stresses within the AMTD were significantly below the maximum yield strength of the device's polymeric blend material. Furthermore, this study also investigated the performance of different fixation assembly materials and found Ti-6Al-4V to be the optimal material choice from those included in this study

Electrospun Structures Made of a Hydrolyzed Keratin-Based Biomaterial for Development of in vitro Tissue Models

The aim of this study is the analysis and characterization of a hydrolyzed keratin-based biomaterial and its processing using electrospinning technology to develop in vitro tissue models. This biomaterial, extracted from poultry feathers, was mixed with type A porcine gelatin and cross-linked with γ-glycidyloxy-propyl-trimethoxy-silane (GPTMS) to be casted initially in the form of film and characterized in terms of swelling, contact angle, mechanical properties, and surface charge density. After these chemical-physical characterizations, electrospun nanofibers structures were manufactured and their mechanical properties were evaluated. Finally, cell response was analyzed by testing the efficacy of keratin-based structures in sustaining cell vitality and proliferation over 4 days of human epithelial, rat neuronal and human primary skin fibroblast cells

Progettazione e realizzazione di un sistema di microfabbricazione multimateriale e multiscala

In questo lavoro di tesi è stata progettato e realizzato un manipolatore parallelo modulare per microfabbricazione di strutture multimateriali e multiscala

Design and fabrication of devices based on Dielectric Elastomer technology for Soft Robotics applications: from materials handling to the Slowbots project

With a view to confirm that dielectric elastomer actuators (DEAs) are one the promising enabling actuation technology for soft robots, this thesis presents the design and fabrication of functional soft robotic devices based on Hydrostically Coupled DEAs (HC-DEAs) with real-world applications. We first propose a soft, compact and light weight platform based on the HC-DEA technology to respond to the need of some areas of the industrial field of systems which can transport/sort delicate objects. This platform, specifically designed to enable the rolling of round objects, consists of an array of HC-DEAs. Experiments on the electromechanical performances on the single HC-DEA are performed and presented. Experimental tests on the proposed platform demonstrate its effectiveness to roll round objects (different in weight and dimensions) when its surface is deformed according to a predetermined pattern of actuation. As example, a 10 mm diameter PVC pipe section and weight of 50 gr, can be transported from one end to the other of the platform at an average speed of around 10 mm/s. In the same context of the previous work, we next present an upgrading design of an existing push-pull Hydrostatically Coupled Dielectric Elastomer Actuator. Its main distinguishing design characteristic is the segmented electrodes which stand as four independent elements on the active membrane. An adequate sequence of activation of the electrodes can generate not only an out of plane motion (push-pull behaviour) but also in plane motion actuation resulting in a multi degree of freedom soft actuator with a roto-translational kinematics. Thanks to its ability to exert both normal and tangential thrusts in any direction in a plane, the novel multi degree of freedom (multi-DoF) HC-DEA enables a variety of possible applications in the field of soft manipulation. In particular, with this thesis intends to demonstrate the possibility of using it as a building block of a modular soft platform aimed at handling delicate objects. Moreover, since each actuator of the platform can be independently controlled by an electric signal, the result could be an easily reprogrammable and reconfigurable soft surface composed by a plane matrix of actuators allowing for both round and flat objects handling. Experimental results demonstrated just two multi-DoF actuation modules, whit a proper actuation cycles of the electrodes, are able to transport a flat object in both translational and rotational directions. Results prove that a Petri dish with a weight of 8 gr and a diameter of 90 mm can be transported in both translational and rotational directions. Specifically, following the application of 3.5 kV as driving voltage, the actuators induced a horizontal translation of the Petri Dish of 3 mm for each actuation cycle and a rotation of about 2.25° for each actuation cycle. Finally, as steps towards to these "soft robotic organisms" this thesis proposes some design concepts with the concrete aim to develop the Slowbots: slow, sustainable, biodegradable and autonomous robots made by soft components. Specifically, it is presented here the fabrication and the electro-mechanical characterisation of pectin based hydrogels with potential application in Slowbots. The hydrogels were fabricated using a solvent casting method dispersing various concentrations of pectin in deionized water and using a CaCl2 solution as crosslinking agent. The electro-mechanical investigation of the hydrogels suggested that due to their low values of apparent elastic modulus (46.45 37.76 kPa) and due to their good conductivity (1.83 S/m is the maximum value recorded) they can be employed as soft conductors for Dielectric Elastomer Actuators on which Slowbots could rely for their locomotive tasks. Moreover, since we found that an increase of temperature in pectin crosslinked matrix can cause an increase of their ionic conductivity, these hydrogels could be used as conductive interface for exteroceptive sensors in order to trigger the activation of the Slowbots on the base of the part of the day, as really happen in organisms in nature. Lastly, pectin hydrogels seem suitable to use in supercapacitors, also called ultracapacitors, to allow the robots to storage energy from the environment and thus to accomplish a set of tasks completely free from tethers

e-garments: Future as "Second Skin"?

Wearing clothing is exclusively a human characteristic. Conventional garment has become the second skin of humans which they missed by nature for the protection purpose that over time transformed the human body into a social and cultural symbol. The history of clothing is immediately linked with the history of textiles, and they are changing every day in line with technological advances and market pressure. Since the 1990s, electronic textiles or e-textiles have been introduced as new emerging concepts and prototypes. Early published literature and journals on the fields of textiles, electronics, and advanced materials have indicated that e-textile-based garment would have a great impact in textile industry to fabricate human second skin replacing the traditional clothes when enhanced properties are needed. More than two decades have elapsed since researchers in this field have begun to work on e-garments achieving excellent results, but these findings have not taken off significantly in terms of market success and consumer adoption. In this chapter, we discuss that a transition from a technology-driven product to a human-driven product can make e-garments the e-second skin for a mass market

Indirect Rapid Prototyping for Tissue Engineering

Tissue engineering (TE) aims at producing patient-specific bio- logical substitutes in an attempt to repair, replace and regener- ate damaged tissues or organs in order to improve the current state of clinical treatments. A three-dimensional substrate, the scaffold, is a key aspect to promote cell organization to form a tissue. Recently, rapid prototyping (RP) technologies have been successfully used to fabricate complex scaffolds, thanks to the ability to create highly reproducible architecture and composi- tional variation across the entire structure, due to their precise controlled computer driven fabrication. The drawback of most of the fabrication principles applied in the RP processes is the requirement of particular conditions (e.g., pressure or tempera- ture) that limit the material choice. Natural polymers, such as collagen, have underlined their superiority for TE solutions but they are challenging to be processed with RP techniques. As al- ternative, scaffold made of natural biomaterial can be produced by indirect fabrication techniques, casting a biomaterial into sacrificial mold realized by RP processes. So far, the indirect rapid prototyping (iRP) has emerged in a number of different ap- proaches with promising results. The present chapter is focused on iRP multistep methods, highlighting strength and weakness and indicating possible future perspectives

Multimaterial and Multiscale Rapid Prototyping of Patient-Specific Scaffold

The majority of strategies used in tissue engineering (TE) employ a scaffold, which is used to guide .the proliferation, the migration and the adhesione of cell in 3D to pruduce an engineered tissue. A new trend in scaffolds’s fabrication is represented by the hybrid Rapid Prototyping technologies. This is a new multimaterial and multiscale fabrication approach which combine the common RP technologies with other micro/nanofabrication techiques to fabricate scaffold that mimick the hetereogenty and hierarchical structure typical of the native extracellular matrix. In this new contest our work present: 1) an innovative device for the fabrication of multi material scaffolds based on an open source FDM 3D printer suitably modified to integrate a multi nozzle deposition tool 2) a design proposal for a multi material and multi scale machine to allow a full control over the modulation of the building materials and of the topography in a scaffold 3) and lastly a CAD workflow to guide the fabrication of RP patient specific scaffolds. Multifunctional hydrogel-based scaffold are fabricated as a demonstration of the validity of the proposed devices. Starting from a clinical case we print a patient-specific scaffold with the aim to recover bone defects at mandibular level as a validation of the proposed CAD process