https://dspace.iiti.ac.in:8080/jspui/handle/123456789/9542 2026-05-15T07:12:42Z https://dspace.iiti.ac.in:8080/jspui/handle/123456789/18103 Title: Investigations on laser direct writing and laser micro-3D printing of metals and ceramics towards MEMS structures printing for functional applications [RESTRICTED THESIS-03 Months] Authors: Singh, Arpit Kumar Abstract: The growing demand for high-performance Microelectromechanical Systems (MEMS) in fields such as biomedical devices, energy harvesting, and flexible electronics necessitates advanced micromanufacturing techniques capable of processing multifunctional materials with sub-micron precision. This thesis investigates two laser-based fabrication methodologies-Laser Direct Writing (LDW) and Laser Micro-3D Printing-to develop metallic and ceramic microstructures tailored for MEMS applications. LDW, employing a 10.6 μm CO₂ laser, is utilized for direct synthesis of porous laser-induced graphene (LIG) on polyimide substrates. Optimized parameters (4.5 W laser power, 15 mm/s scan speed) produced uniform graphene structures exhibiting high conductivity and porous morphology, confirmed by Raman spectroscopy with characteristic D (~1350 cm⁻¹), G (~1580 cm⁻¹), and 2D (~2700 cm⁻¹) peaks. The fabricated LIG-based strain sensors demonstrated excellent mechanical resilience, surviving over 1250 bending cycles without degradation. 2026-04-07T00:00:00Z https://dspace.iiti.ac.in:8080/jspui/handle/123456789/18095 Title: Atomistic modeling and experimental investigations of carbon nanotube-based systems for hydrogen storage and leakage mitigation [RESTRICTED THESIS-Six Months] Authors: Mishra, Saurabh Abstract: [Abstract is restricted for Six-Months, due to IPR related issue] 2026-03-14T00:00:00Z https://dspace.iiti.ac.in:8080/jspui/handle/123456789/17607 Title: Thermal management of battery modules using phase change composite and liquid cooled plates Authors: Saxena, Vivek Abstract: This dissertation presents the theoretical and experimental investigations pertaining to the Phase Change Material (PCM) based passive and hybrid thermal management systems for electric vehicle battery modules. The objective of the present study is to analyse the performance of PCM based passive and hybrid thermal management systems for various applications, more specifically for battery modules of electric vehicles. Initially, a theoretical model has been proposed to estimate the effective thermal conductivity (ETC) of open-cell metal foams (MFs) saturated with fluid or phase change materials (PCMs). These models incorporate realistic geometric characteristics (3-D) based on tetrakaidecahedron unit cell structures, incorporating different shapes of ligament and various shapes of node, orientation of ligament, geometry of MFs, coating thickness, and effect of materials. Among various models, the hexagonal-cell model featuring concave triprism ligaments and pyramidal nodes exhibits very good agreement with test data, with deviations below 3% for coated nickel and copper foams. The parametric study further highlights coating thickness as the most influential parameter, followed by the thermal conductivities of the coating material and the filler medium. 2025-12-19T00:00:00Z https://dspace.iiti.ac.in:8080/jspui/handle/123456789/17604 Title: Flow physics of micro particles suspended in viscoelastic fluid in a microchannel Authors: Soni, Prithviraj Abstract: This thesis presents a detailed numerical investigation into the behavior of microparticles in viscoelastic fluid environments within microfluidic channels of varying geometries. The study aims to understand how channel design and fluid properties influence particle migration, focusing particularly on passive manipulation strategies driven by elastic lift forces. Using COMSOL Multiphysics 6.0, a simulation model was first developed and validated by replicating results from a previously published, experimentally verified study. The replicated outcomes closely matched the reported experimental trends, establishing the reliability of the simulation framework. Following this validation, the channel geometry was systematically altered to explore the effects of various symmetric and asymmetric well configurations—such as rectangular, triangular, and curved cavities—on particle deviation and focusing efficiency. Simulations were conducted across a range of flow rates (20–40 μL/min) and PEO (polyethylene oxide) concentrations (500 ppm and 1000 ppm), with fixed particle size (4.8 μm) to mimic red blood cells. Results showed that increasing polymer concentration enhanced viscoelastic lift forces, leading to more pronounced lateral particle migration. Moreover, complex geometries, particularly those with sharp transitions like double-sided triangular wells, produced stronger elastic focusing effects compared to simpler or smoother designs. 2025-07-07T00:00:00Z