Please use this identifier to cite or link to this item:
|Title:||DESIGN, FABRICATION, AND CHARACTERIZATION OF MICRO-ELECTROMAGNETIC DEVICES FOR MANIPULATION OF MAGNETIC PARTICLES|
|Abstract:||Molecular analysis for disease management is performed in equipped laboratories by specialists. This process can be slow, costly, and inaccessible in remote rural areas. This inspires the need for developing highly specific, and robust lab-on-a-chip (LOC) devices. Analyte separation is an essential step for molecular diagnosis. Among micro-scale separation techniques, magnetophoresis benefits from its high throughput, relatively non-invasive nature, integrability, and availability of magnetic particles in variety of sizes and coatings. Magnetic forces are applied on magnetically tagged objects using permanent magnets, ferromagnetic micro/nano-structures (passive), or electromagnets (active). In this thesis, we integrate active and passive elements, by coupling micro/nano-structured electromagnets with ferromagnetic materials, to capture MPs at low currents (< 50 mA). These active-passive devices are fabricated using benchtop techniques such as xurography, polymer induced thin film wrinkling, spin coating, and electrodeposition. An efficient transport of analytes inside LOC platforms is essential for reducing the sample-to-response time and improving the limit-of-detection. Micro-electromagnetic devices are suited for this task due to their high level of controllability over the generated magnetic force. However, the magnetic force attenuates rapidly as we move away from the surface of the device. Elevating the current improves the magnetic strength in expense of destructive Joule heating and high-power consumption. In this work, we investigate the combined role of temperature and magnetic field gradients on the motion of MPs to extent the capture zone of the device beyond its surface. We show that the measured terminal velocities of particles located near the magnetic traps (∼5.5 μm) replicate the values provided by the simualtions. Remarkably, we demonstrate two orders of magnitude deviation between the experimental and simulation results for the terminal velocities of far particles (∼55.5 μm). By modelling the heat transfer of the system, we demonstrate that this inconsistency is due to the fluid movement caused by convection. Magnetophoretic cell manipulation in a free-flow condition is beneficial in terms of high throughput and integrability. Here, after integrating the active-passive device with microfluidic channels, we successfully capture and release magnetically tagged-yeasts in a continuous flow with an applied current of 30 mA. Micro/nanotextured lubricant-infused surfaces can be applied to LOC devices, due to their self-cleaning, frictionless, and high surface area properties. In this thesis, we integrate the wrinkling process and fluorosilanization to develop conductive lubricant-infused surfaces that are electrochemically active, slippery, and anti-biofouling. Self-assembled monolayers of fluorosilane are deposited on gold-coated shrinkable substrates. After creating the micro-wrinkled structures by heating the substrate (160°C), a lubricant is applied to the surfaces. High water contact (~150°) and low sliding angles (<5°), along with manipulation of magnetic droplets in a friction-less fashion, confirm the hydrophobicity and slipperiness of these surfaces. We demonstrate that these surfaces can prevent non-specific adhesion of proteins, which is crucial for surface-based biosensors.|
|Appears in Collections:||Open Access Dissertations and Theses|
Files in This Item:
|Hosseini_Seyed_MA-201901_PhD.pdf||4.49 MB||Adobe PDF||View/Open|
Items in MacSphere are protected by copyright, with all rights reserved, unless otherwise indicated.