Multiphase modelling of an experimental device for conformal coating of pancreatic islets

This paper illustrates the development of an SPH model for the analysis of a relatively complex multiphase flow occurring in an experimental microfluidic device for encapsulation of islets of Langerhans (i.e. pancreatic cells aggregates) through a bio-compatible and permeable polymeric coating. Cell encapsulation guarantees optimal immunoisolation while allowing glucose and insulin diffusion, thus enhancing the possibility of transplantation without immunosuppression in Type-1 diabetic patients to restore correct glucose metabolism. A WCSPH numerical modelling, based on the formulation by Adami et al. (2010), of the multiphase flow in the experimental device proved to be phase conservative with respect to finite volume / finite element models early setups, and is able to accurately mimic the encapsulation process. The SPH model allows evaluating: (i) the feasibility of reproducing the physical phenomenon leading to islet encapsulation, such as surface tension at the interface and physical viscosity of both fluids (as shown experimentally by Suryo & Basaran, 2006); (ii) the influence of modulating different process parameters on the fluid dynamics and coating characteristics; and (iii) to overcome the limits of the early numerical model while increasing the resolution. The model represents a valuable, time-and cost-effective tool for further refinement of the experimental process

Smoothed Particle Hydrodynamics multiphase modelling of an experimental microfluidic device for conformal coating of pancreatic islets

•SPH model of the flow in a device for pancreatic islets conformal coating.•Encapsulation process suitably reproduced while assuring phase conservation.•Simulation of jet fragmentation and surface tension effects on islet coating process.•Evaluation of influence of process parameters on the shape of encapsulated islets. The paper discusses a Smoothed Particle Hydrodynamics (SPH) model for the analysis of the multiphase flow occurring in an experimental microfluidic device for conformal coating of pancreatic islets with a biocompatible and permeable polymer. The proposed numerical model, based on a weakly-compressible SPH approach, accurately mimics the encapsulation process while assuring phase conservation, thus overcoming potential limitations of grid-based models. The proposed SPH model is a triphasic multi-phase model that allows one: (i) to reproduce the physics of islet conformal coating, including the effects of surface tension at the interface of the involved fluids and of the islet diameter; and (ii) to evaluate how modulation of process parameters influences the fluid dynamics within the microfluidic device and the resulting coating characteristics. This model can represent a valuable, time- and cost-effective tool for the definition of optimized encapsulation conditions through in silico screening of novel combinations of conformal coating parameters, including polymeric coating blends, size range of insulin-secreting cell clusters, utilized chemical reagents, device geometry and scale