Portfolio

2025

1. Unraveling the Processing Parameters for Selective Positioning of Multi-materials Using Laser Decal Transfer

   Arpit Kumar Singh, Anshu Sahu, K. A. Vyvaswath, Kailaash Pandiyan, and 1 more author

   Journal of Materials Engineering and Performance, 2025

   Abs DOI

   3D printing or additive manufacturing has gained popularity due to its high innovation potential, process improvement, and design freedom in industries such as aerospace, dental, medical, and automotive. A detailed investigation into thin film as a feedstock for printing maskless MEMS structures is an important area of current research. In this work, we explore the selective positioning of ZnO ceramic over a NiTi interdigitated structure on an ITO-coated glass substrate using the laser decal transfer technique. A CO2 laser (λ = 10.6 µm) is employed, and the effects of laser processing parameters—including laser fluence, laser pulse overlaps, and stand-off distance—are systematically analyzed. Key experimental findings indicate that a laser fluence of 75 J/cm2 optimally facilitates ZnO transfer while avoiding material burning. A stand-off distance of 12.5 cm allows effective material transfer, whereas off-focus conditions hinder ZnO deposition. Additionally, an optimal laser pulse overlaps of 65% achieves a balance between continuous material transfer and minimal heat-affected zone. The transferred ZnO seed layer, approximately 5 µm thick, is further hydrothermally grown into well-structured ZnO nano-rods, confirmed through SEM and XRD analysis, which identifies a hexagonal wurtzite crystal structure. Finally, using optimized parameters, the feasibility of multi-material transfer is demonstrated, with successful ZnO deposition on a NiTi interdigitated structure (600 µm feature size), forming a layered structure. The proposed laser micro-3D printing via laser decal transfer offers significant advantages for fabricating complex sensors with controlled gradient-based properties.

2024

1. Understanding the Heat Transfer Characteristics and Axis Switching Phenomenon in High Aspect Ratio Elliptical Orifice Impinging Synthetic Jets

   Pawan Sharma, Prakhar Bharadwaj, Kshitij Bhat, K. A. Vyvaswath, and 4 more authors

   In Fluid Mechanics and Fluid Power, Volume 1, 2024

   Abs

   The present experimental study focuses on analyzing the heat transfer characteristics and understanding the axis switching phenomenon for impinging elliptic jets with high aspect ratios. The hot-wire anemometry is used to study the flow characteristics of synthetic jet, while heat transfer characteristics are studied by using a thermal imaging technique. The heat transfer characteristics of elliptical orifices with aspect ratios 10 & 14 are being studied and compared to an equivalent circular orifice. Results show that in the near-field region (}}z/d\backslashle 3}}z/d≤3), the average Nusselt number of elliptical orifices (AR\thinspace=\thinspace10 &14) is obtained to be higher than the circular counterpart. However, with the rise of AR from 10 to 14, thermal performance of elliptical orifices decreases in the near-field region. In the intermediate and far-field region, the thermal performance of such elliptical orifices depreciates, since most of the momentum of the elliptic jet is lost before arriving at the impingement plate due to significant entrainment and substantial mixing with the ambient fluid. It is also observed that with orifice to surface spacing, circular orifice jet produces a single peak in the average heat transfer rate, while elliptical orifice produces double peaks in the average heat transfer rate lying in near-field (z/D\thinspace=\thinspace1 to 3) and mid-field regions (z/D\thinspace=\thinspace6 to 10).

2. A Gesture-Controlled SMA-Actuated Robotic Gripper System and Method Thereof

   2024

   Patent Application No. 202421051320 - Published and under examination