Advanced microfluidic platforms and responsive surface technologies for modulating cellular behaviour

Tissue injury, even something as minor as a small scratch, triggers a highly coordinated cascade of cellular events aimed at protecting the body from pathogens and restoring tissue integrity. This process involves immune cell recruitment, phenotype transitions, and extracellular matrix remodelling, all directly interacting with physical (shifting tissue properties, physical restructuring of the extracellular matrix), chemical (communicating cells), and electrical (electrical gradients across the injury) cues in the tissue environment. However, the multifactorial and time-dependent nature of these cellular processes remains challenging to study using conventional static culture systems, which fail to capture the dynamic interplay of biological and physical signals during healing. This thesis addresses this challenge by developing advanced microfluidic and responsive surface platforms that enable precise, real-time modulation of cellular environments, with a focus on how macrophages and fibroblasts respond to dynamic physical stimuli such as electrical and mechanical cues. Central to the work is the development of long-term digital microfluidic (DMF) platforms and light-responsive liquid crystal (LC) surfaces that enable precise control over cell culture environments and immune modulation. First, a long-term DMF platform was engineered based on a multilayer dielectric stack of PVDF and SU-8, providing, for the first time, electrical stability and humidity resistance for up to 60 days. This system maintained high macrophage viability and allowed controlled studies of inflammatory polarisation. Upon stimulation with lipopolysaccharide (LPS) and Interferon gamma (INF-γ), macrophages adopted a pro-inflammatory phenotype, which was reversed by treatment with TCB-2, a selective serotonin 5-HT2A receptor agonist, restoring anti-inflammatory cytokine profile and cell morphology. To further investigate immune modulation through bioelectric signals, the platform was integrated with an electrostimulation module capable of delivering waveform-specific electrical signals to localised injury models. The novel electrode design allows to culture four independent injury models per chip with spatially controlled electrostimulation to injury core or scar tissue surrounding it. The optimised PVDF passivation layers ensured minimal current leakage and high signal fidelity. Electrostimulation was found to modulate the macrophage phenotype in a waveform-dependent manner, where sinusoidal and pulsed signals promoted anti-inflammatory states and suppressed acute-phase cytokine release. Next, the thesis explored the role of dynamic mechanical cues in regulating cell behaviour using light-responsive LC surfaces capable of reversible topographic changes, mimicking dynamic extracellular matrix conditions. Fibroblasts cultured on grooved topographies exhibited enhanced mechanosensitive signalling, increased Yes-associated protein (YAP) nuclear translocation, and localised focal adhesion formation. Sequential exposure to different surface topographies amplified cellular responses, revealing mechanical memory and cellular plasticity. Extending this concept to immune cells, macrophages cultured on LC films showed topography-dependent immune modulation. Grooved surfaces triggered mixed phenotypes with elevated cytokine secretion and increased membrane dynamics, while pillared surfaces maintained a stable anti-inflammatory profile. Sequential exposure further amplified macrophage responsiveness, indicating that previous mechanical stimuli can influence future immune behaviour. Together, these results demonstrate that dynamic electrical and mechanical cues can be harnessed to modulate immune cell behaviour in vitro. The platforms developed in this work provide scalable and biocompatible tools for studying inflammation, immune plasticity, and regenerative processes, paving the way for next-generation electroceutical and mechanoresponsive therapeutic strategies.