APPLICATIONS OF MICROSCOPIC FLUID FLOW: PART A: OBLIQUE DROPLET IMPACT ON MICROHOLED HYDROPHILIC SUBSTRATE PART B: DESIGN OPTIMIZATION OF A FISH-ON-CHIP DEVICE FOR NEUROLOGICAL STUDY

Tushar Nath

doi:10.7273/000007434

Microscopic fluid flow occurs at micrometer to millimeter scales where the flow is usually laminar, dominated by viscous forces over inertial forces and significantly influenced by surface tension, capillary action and wall effects. It plays a crucial role in various engineering and biomedical applications. This thesis explores two distinct yet interconnected aspects of micro-scale fluid interactions: (1) dynamics of oblique droplet impact on microholed hydrophilic substrate and (2) the design optimization of a microfluidic device for zebrafish larval culture to study microbiome-neurological interactions, specifically sensorineural hearing loss. In the first part, I investigated the behavior of a water droplet on an inclined hydrophilic surface with a microhole at the center of it for inclination angles ranging from 0° to 30°. The droplet exhibited asymmetric spreading due to the interplay between surface energy and tangential velocity component. I identified almost consistent normal Weber numbers (WeN) across different jetting (through the microhole) regimes (i.e., no pinch off, single pinch off, multiple pinch off) and established a power-law relationship for maximum spreading of the droplet along the tangential direction, βm ∼ WeN0.27, independent of inclination angle within the experimental range of inclination angles. The power law was found to be in good agreement with the literature models. However, deviation may be anticipated at higher angles which is out of the scope of this study. The time for maximum spreading of the droplet along the tangential direction was found to be quite independent of the inclination angle within the experimental range for a certain WeN. Additionally, jet velocity scaled linearly with impact velocity, while pinch-off time and maximum jet length showed predictable trends with capillary dynamics. In the second part, two Fish-on-Chip (FOC) devices (Design A and Design B) were developed and evaluated for their effectiveness in supporting zebrafish embryo development over a four-day culture period. Design A, while simpler to fabricate, exhibited higher flow rates and lower hatching success due to unfavorable geometry. Design B, with a more complex dual-layer PDMS structure, demonstrated improved flow control and significantly higher hatching rates. However, both designs resulted in reduced larval length compared to controls, indicating the need for further refinement to ensure optimal developmental conditions within the chip environment. Together, these investigations advance understanding of fluid behavior at the microscale and contribute toward the development of microfluidic platforms for biological studies.

APPLICATIONS OF MICROSCOPIC FLUID FLOW: PART A: OBLIQUE DROPLET IMPACT ON MICROHOLED HYDROPHILIC SUBSTRATE PART B: DESIGN OPTIMIZATION OF A FISH-ON-CHIP DEVICE FOR NEUROLOGICAL STUDY

Files and links (1)

Abstract

Metrics

Details