Author ORCID Identifier
Semester
Summer
Date of Graduation
2024
Document Type
Dissertation
Degree Type
PhD
College
Eberly College of Arts and Sciences
Department
Chemistry
Committee Chair
Peng Li
Committee Co-Chair
Stephen J. Valentine
Committee Member
Stephen J. Valentine
Committee Member
Justin Legleiter
Committee Member
Blake Mertz
Committee Member
David Klinke
Abstract
Capillary Vibrating Sharp-edge Ionization device (cVSSI device) was developed by our laboratory with a low cost and an easy fabrication procedure. The generation of small liquid droplets by this technique has been used as an ionization source for mass spectrometry analysis platforms. On usual applications incorporating the cVSSI device a syringe pump was connected to the back end of the vibrating sharp tip capillary to ensure continuous loading of sample into the capillary to sustain the ionization process at the tip end of the vibrating sharp tip capillary. We were able to observe that upon the generation of droplets the mechanism induces a pulling effect on the flow of liquid coming out from the vibrating sharp tip capillary. This pulling effect was sufficient to induce a fluid flow through the capillary to sustain the ionization process. In this dissertation I demonstrate the development of the acoustic atomization induced pump based on a vibrating sharp tip capillary and how its vibration performance was optimized for efficient droplet generation. Chapter 2 focuses on the development of the acoustic atomization induced pump based on the vibrating sharp tip capillary. The negative pressure is generated to drive the movement of fluid without the need to fabricate special microstructures or use special channel materials. We hypothesized several strategies that would influence and enhance the pumping effect by vibrating the sharp tip capillary. Thereby we studied the influence of the frequency, input power, internal diameter (ID) of the capillary tip, and liquid viscosity on the pumping flow rate. By adjusting the ID of the capillary from 30 µm to 80 µm and the power input from 1 Vpp to 5 Vpp, a flow rate range of 3 to 520 µL/min can be achieved. We also demonstrated the simultaneous operation of two pumps to generate parallel flow with a tunable flow rate ratio. Finally, the capability of performing complex pumping sequences was demonstrated by performing a bead-based ELISA in a 3D-printed microdevice.
In chapter 3, I demonstrate how the acoustic atomization based vibrating sharp tip capillary pump was miniaturized and was embedded into a microchip. This enabled portability to the microfluidic platform further facilitating the integration of several independently controllable micro pumps embedded into the same microchip. The present method allows the independent control of each pumping unit, and the pumping performance is independent of the channel material and other microstructures. We were able to avoid the use of excessive tubing and narrow down the footprint of the acoustic pump to less than 12 cm2. We studied the relationship between flow rates and other design parameters such as capillary tip OD, input power and frequency. We were able to achieve flow rates in the range of 0.118 – 632.607 µL/min. We further demonstrated the adaptability of this system in studying the kinetics of GAPDH enzyme on a multi-pump setup.
In chapter 4 the enhancement of the vibration performance of the vibrating sharp tip capillary was investigated. Acoustic streaming is generated by dissipating acoustic energy into the boundary layer of the vibrating solid body. The occurrence of this phenomenon as well as the generated streaming patterns depends highly on the geometry of the vibrating solid body. Acoustic streaming generated by a vibrating sharp structure has caught much attention due to its high energy efficiency and its ability of the sharp structures to generate them at low frequencies in the kHz range. Recently, our group developed an acoustically oscillating sharp tip capillary that was able to generate strong acoustic streaming when immersed in a fluid domain. On a previous work the efficiency of the generated acoustic streaming was observed by immersing the vibrating sharp tip into a fluid that carries fluorescent micro particles and measuring the velocities of the streaming patterns. From those previous studies it was concluded that the presence of liquid inside the glass capillary affected the generated streaming patterns by changing the direction of streaming as well as by increasing their velocities thereby increasing the energy efficiency of the vibrating sharp tip capillary. Here in this chapter, I demonstrate how the vibration performance of the liquid filled vibrating sharp tip capillary device was optimized as well as how the energy efficiency was enhanced. We hypothesized and investigated several key geometric parameters that can be used in optimizing the energy efficiency of the vibration performance of the vibrating sharp tip capillary. We studied the effect of tip geometry under 2 key factors namely tip OD & taper length and studied the velocity of the streaming patterns, generated by pulled tip liquid filled capillaries as well as by pulled tip solid probes. Through the observations it was able to conclude that the vibration performance of the pulled tip solid and hollow probes wasn’t an effect from just one parameter (tip OD) but rather a combination of different parameters (tip OD and taper length). The vibration intensity (Indicated by the streaming velocity) is decided upon by the combined effect from OD and taper length. Further it was concluded that liquid filled pulled tip hollow probes offer better vibration efficiency compared to the pulled tip solid probes.
Recommended Citation
Mendis, Balapuwaduge Lihini Tharanga Catherine, "Development of Lab-on-a-Chip platforms incorporating a novel Acoustic atomization induced pump based on a vibrating sharp edge capillary." (2024). Graduate Theses, Dissertations, and Problem Reports. 12586.
https://researchrepository.wvu.edu/etd/12586
Embargo Reason
Publication Pending