Robotic digital microfluidics: a droplet-based total analysis system.

Developing automated platforms for point-of-need testing is a crucial global demand. Digital microfluidics is a promising solution for expanding integrated testing devices featuring ultimate control over the chemical and biological reactions in micro/nanoliter droplets. In this study, robotic digital microfluidics (RDMF) is introduced for the mechanical manipulation of the droplets precisely and inexpensively. A controllable and multifunctional arm equipped with several actuators is responsible for dispensing and manipulating droplets on a disposable superhydrophobic cartridge. The platform has been demonstrated with diverse functions, including droplet dispensing, transport, mixing, aliquoting, and splitting. Moreover, incorporating magnetic and heating modules into the system can realize particle manipulation and droplet heating. The liquid handling operations are investigated from both experimental and modeling perspectives. Handling a wide range of droplet sizes without needing high-voltage electric sources, integrability with different detection techniques, and ease of manufacturing are the main advantages of the RDMF platform compared to conventional digital microfluidic systems. The availability of a complete fluidic toolbox and multiple detection choices make RDMF promising for droplet-based total analysis technology. The system was applied for a urinalysis test to show its versatility in handling complex biochemical assays. The results entirely matched those obtained based on laboratory gold standard techniques.

Experimental evaluation of the effect of positioning and operating parameters on the performance of a surface-piercing propeller.

Today, surface-piercing propellers have been recognized as a suitable choice for higher speeds. Yet, the development of design algorithms for such has been challenged by insufficient knowledge about the parameters affecting their performance. For this reason, developing experimental data and studying the influence of various parameters on their performance is crucial. Aiming to develop experimental knowledge of these propellers, this study investigates the impact of position parameters and Froude Number on model test results of a custom-designed propeller. Moreover, ventilation wake development at different Froude numbers was studied. The experimental results pointed to the favorable impact of increased immersion ratio on propeller's thrust, a positive impact of increasing the inclination angle by 6° on higher thrust and efficiency in the advance direction, and a slight increase of thrust with higher yaw angles up to 10°. The propeller's lateral forces were also extracted in different positions and operational conditions to identify the propeller's behavior and design the required shaft and supports. Finally, regression equations for projecting hydrodynamic coefficients used at the design phase were compared and verified by the experimental results. The results pointed to the insufficient precision of this model for estimating the hydrodynamic coefficients affecting the propeller.