Microfluidic chip development for medical application

The advent of thermoplastics used in bio-medical applications has brought forth the possibility of low cost, mass fabrication of disposable microfluidic devices. Ensuing this new technology, research in the bonding techniques of polymer substrates has gained traction, in aims to produce repeatable, quality high strength joints.! Current research has identified the uncontrollable energy director melt flow as a major problem in manufacturing these microfluidic devices, complicating capillary flow actions, leading to unpredictable fluidic flow.! The present study proposes a novel method in the fabrication of microfluidic chips in aims to attempt to reduce the effect of uncontrollable melt flow with a layer of PDMS introduced with PMMA powder via ultrasonic bonding. Hence, focus is given to the bonding of, resulting bonding strength via a tensile pull test.! Preliminary experimentations done in this project involves the weld time weld mode for the ultrasonic bonding process. Parametric studies established the optimal parameters to be at 0.2 mm depth RPN, 100% vibration amplitude, 100 N weld force, and a welding time of 1.5 s. At these parameter settings, bond weldings produced are with good weld areas with the capability to stand up to forces exceeding 400 N, with bonds withstanding tensile stress exceeding 27 MPa. The introduction of PMMA powder in PDMS layer proved to be effective at PMMA to PDMS weight concentrations of 0.227, however poor welding is being observed at the established optimal parameters, and pull test failure occurred at the spin coating interface between the PDMS layer and PMMA bonding plate (substrate). The results obtained in this project is not conclusive enough to determine the success of controlling energy director melt flow, but it presents a stepping stone for future work to be done to determine the feasibility of the proposed method. Bachelor of Engineering (Mechanical Engineering