Sepsis is an autoimmune disease where a bacterial infection causes organ failure. Early diagnosis is a challenge when using traditional methods. Improvement in early detection is vital in treating patients with sepsis. One method for early detection is through the use of particle deposition patterns from patient urine. Deposition patterns are the remaining particles from an evaporating droplet and can vary based on a variety of factors. To optimize sepsis detection, a digital microfluidic device can be used to manipulate the deposition pattern of a sample to detect target proteins. These devices use microarrays for improved biomarker detection. Microarrays consist of arrays of hundreds or even thousands of sessile droplets on a substrate and can be used in several biological applications. These microarrays rely on the application of an electric field to control particle deposition.
Recent efforts have examined the effects of applying electric fields to evaporating droplets to actively control colloidal transport and deposition in evaporating droplets. To improve target protein detection, electrowetting on dielectric (EWOD) is performed to manipulate particle deposition patterns from evaporating droplets. A further understanding of the affects an electric field has on an evaporating droplet would improve device sensitivity. The ability to manipulate the contact line of a droplet is a critical factor in determining fluid dynamics in a droplet. The dynamics of an evaporating droplet ultimately determine the transport and deposition of particles. This thesis focuses on accurately quantifying the forces that affect droplets with and without particles when EWOD. Understanding the forces acting on a droplet will assist in improving manipulating particle deposition patterns. With this goal in mind, the following has been accomplished within this thesis: proposed a new experimentally validated model for hysteresis under AC electrowetting, verified the proposed model on a variety of different surfaces suitable to EWOD, and performed a preliminary investigation to the effects of particles on hysteresis.
Manufacturing costs limit the availability of many LOC devices as a medical diagnostic tool. Typically, a cleanroom facility with expensive equipment and processing is required to manufacture LOC devices. A potential alternative would be to use an inkjet printer and conductive ink to print electrodes at a much lower cost. These devices could then be coated with a dielectric and hydrophobic layer outside a cleanroom. This thesis verifies if inkjet-printed (IJP) devices are a feasible substitute for cleanroom-fabricated (CRF) devices as EWOD devices.
Mechanical Engineering (MS)
Department, Program, or Center
Mechanical Engineering (KGCOE)
Bernetski, Kimberly, "Contact Line Pinning Under AC Electrowetting" (2019). Thesis. Rochester Institute of Technology. Accessed from
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