Investigating the flow dynamics in the obstructed and stented ureter by means of a biomimetic artificial model

Double-J stenting is the most common clinical method employed to restore the upper urinary tract drainage, in the presence of a ureteric obstruction. After implant, stents provide an immediate pain relief by decreasing the pressure in the renal pelvis (P). However, their long-term usage can cause infections and encrustations, due to bacterial colonization and crystal deposition on the stent surface, respectively. The performance of double-J stents - and in general of all ureteric stents - is thought to depend significantly on urine flow field within the stented ureter. However very little fundamental research about the role played by fluid dynamic parameters on stent functionality has been conducted so far. These parameters are often difficult to assess in-vivo, requiring the implementation of laborious and expensive experimental protocols. The aim of the present work was therefore to develop an artificial model of the ureter (i.e. ureter model, UM) to mimic the fluid dynamic environment in a stented ureter. The UM was designed to reflect the geometry of pig ureters, and to investigate the values of fluid dynamic viscosity (μ), volumetric flow rate (Q ) and severity of ureteric obstruction (OB%) which may cause critical pressures in the renal pelvis. The distributed obstruction derived by the sole stent insertion was also quantified. In addition, flow visualisation experiments and computational simulations were performed in order to further characterise the flow field in the UM. Unique characteristics of the flow dynamics in the obstructed and stented ureter have been revealed with using the developed UM

Droplet interfaced parallel and quantitative microfluidic-based separations

High-throughput, quantitative, and rapid microfluidic-based separations has been a long-sought goal for applications in proteomics, genomics, biomarker discovery, and clinical diagnostics. Using droplet-interfaced microchip electrophoresis (MCE) techniques, we have developed a novel parallel MCE platform, based on the concept of combining the Slipchip principle with a newly developed “Gelchip”. The platform consists of two plastic plates, with droplet wells on one plate and separation channels with preloaded/cured gel in the other. A single relative movement of one plate enables generation and then loading of multiple sample droplets in parallel into the separation channels, allowing electrophoretic separation of biomolecules in the droplets in parallel and with high-throughput. As proof of concept, we demonstrated the separation of 30 sub-nL sample droplets containing fluorescent dyes or DNA fragments