Designing, modelling and manufacturing composite hydrogels for biomedical applications

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This project has two key objectives: firstly, it aims to contribute to the 4D printing design space; with use of Abaqus and python smart composite materials can be modelled, and their subsequent shape changes simulated. This allows a user to model 4D composite materials and follow their triggered deformation over a period of time. The second objective will be to manufacture a 4D printable bio-inductive hip implant, this will be tested in various campaigns in order to optimise for use in-vivo. The aim is to use 4D materials to provide value to humans.Osteoarthritis affects upwards of 250 million people worldwide; currently there is not a simple effective treatment that addresses the cause of the problem. Hence, one asks, can a 4D material be used to support and regenerate damaged joint interfaces? Both key objectives for the project will be carried out in unison, designed to support and optimise each other; modelling experiments should supplement physical experiments and vice versa.Modelling in the 4D design space will be used to carry out exploratory experiments, allowing time in the laboratory to be focused and succinct. 4D material modelling will investigate the effect of hierarchical structure, i.e., can nano/micro-structures direct macroscopic shape change? This involves composite material modelling that explores micro/nano structures within a larger framework, enabling direct and intelligent shape change to provide support and growth where necessary. 4D material modelling will allow for a holistic material testing approach, many materials can be tested in a relatively short period of time. Thus, generating the most desirable material properties for supporting and stimulating a human hip joint. Following this, it will be possible to pick physical materials that closely match the most desirable material properties. In addition, multiple different material blends will be tested, producing tuneable material properties.A stereolithographic 3D printer will be used to manufacture materials for testing, the printer utilises ultra-violet light to cure a resin instantaneously to produce a solid structure. Various printing methods will be investigated to produce the best material properties, the aim is to mimic material properties found within the body to provide the best support. Additive manufacturing produces anisotropic material properties, paired with complex loading patterns in the hip joint. It is essential that material properties are maximised in the appropriate plane. Thus, experiments will investigate how the angle of printing affects anisotropic material properties giving the optimal printing angle for implant manufacture. Furthermore, greyscale lighting techniques will be used during the cure process to produce functionally graded materials, this will mimic the joint interface that is found in a healthy human to provide further support. Modelling campaigns will supplement multi-material manufacture, in order to provide information on the most effective material blends for implant manufacture. Material testing will initially involve simple compression and shear testing outlined by standard ASTM manuals. As the project progresses, the aim will be to build a pseudo hip-joint in order to mimic the complex loading environment found within a human hip joint. In order for use in-vivo, biocompatibility must be investigated, the structure must interact in a complementary sense with the human body. Thus, experiments will be carried out to determine biocompatibility to avoid complications with implant insertion. Steps will be taken to produce a more advanced implant that stimulates joint regrowth. By incorporating bio-inks within the manufacturing process it is possible to stimulate positive regrowth, the aim will be to manufacture an implant that is bio-inductive. A bio-inductive implant will regenerate the joint interface and subsequently degrade as it is no longer needed.