Injection moulding is recognised as one of the most efficient mass production technologies for manufacturing polymeric components that have been used widely in agricultural,biomedical,mechanical and opto-electronic industries.The performance and functionality of these polymeric microscale devices rely on the precision replication of surface structures.However,the replication of surface structures is complicated and not yet fully understood.Commercial software for injection moulding is available to optimise the mould design for macroscale products,but such software cannot accurately simulate the moulding process and defects for microscale surface structures.Moreover,applications such as optical lenses simultaneously require satisfactory geometric accuracy,surface quality and stress birefringence,which is difficult.This thesis focusses on two typical applications when analysing the filling behaviour of surface structures and developing injection moulding processes to produce polymeric components with high geometric accuracy,adequate replication of surface structures and low residual stress.Firstly,a microfluidic flow cytometer chip with essential surface structures is used as a typical model to study the filling process.Short-shot experiments and single factor experiments are performed to examine filling during the injection and packing stages of the injection moulding process.The influence of process parameters such as shot size,packing pressure,packing time and mould temperature are systematically monitored,characterised and correlated with 3D measurements and physical response of the machine such as screw velocity and screw position.A combined melt flow and creep deformation model is proposed to explain the complex influence of process on replication.An approach of over-shot injection moulding is suggested and is shown to be effective at improving the replication quality of these surface structures.Moreover,a feasible approach to describe the filling of the surface structures using commercial simulation software is developed.Factors including the heat transfer coefficient,venting,wall slip and freeze temperature that were critical for microinjection moulding but not of primary importance for conventional injection moulding are specifically investigated.Based on process monitoring and a series of experiments and validation,the insufficient filling of surface structures is successfully predicted.The heat transfer coefficient is shown to have a significant impact on the replication of surface structures.Venting and wall slip are both critical in simulating the filling process.This approach proved to be effective and can be used to predict defects when moulding surface structures,while the simulation accuracy has scope for further improvement.Secondly,a systematic and comprehensive analysis is conducted of a practical microlens array that is designed for light-field applications.Process parameters are screened and optimised using a two-stage design of experiments approach.Then,a variotherm mould temperature control system is used to further improve the replication.Based on in-line process monitoring and a quantitative and qualitative evaluation being carried out in terms of geometric accuracy,surface quality and stress birefringence,the replication is shown to relate directly to machine settings and dynamic machine responses.Variotherm-assisted injection moulding can significantly reduce residual stresses while maintaining excellent geometric accuracy and surface quality.Afterwards,an innovative in-mould microcompression system was developed to provide high precision compression that is in the magnitude of micrometres during the injection moulding process.In terms of the aforementioned evaluation criteria,the effect is examined based on conventional injection moulding and variotherm assisted injection moulding.The in-mould microcompression system can optimise stress birefringence and both replication and uniformity of geometric accuracy and surface quality of the microlens arrays.Additionally,it can improve the form replication of a typical thick aspheric lens.