Under this research area, we use optical printing and laser-assisted colloidal assembly represent a coherent and progressive body of work that demonstrates how light–matter interactions can be harnessed for controlled nanoparticle patterning, biological manipulation, and functional device fabrication. His early work laid the foundation for laser-induced assembly by demonstrating the directed immobilisation of biological cells and colloids onto candle soot–coated substrates, where localised laser heating generated thermophoretic and convective flows that enabled selective particle deposition without chemical functionalization or complex lithography [1]. This study provided key mechanistic insights into substrate-mediated laser heating and its role in particle transport and immobilization. Building on this understanding, subsequent work extended optical printing to plasmonic nanoparticles, showing that laser-induced plasmonic heating can be exploited to print nanoparticle patterns with high spatial control while simultaneously enabling thermophoretic assembly of biological cells [2]. These optically printed plasmonic structures functioned as efficient surface-enhanced Raman spectroscopy (SERS) substrates, demonstrating strong Raman enhancement and highlighting the dual utility of optical printing for both nanofabrication and biosensing [2]. A comprehensive mechanistic framework was later developed by systematically comparing plasmonic and non-plasmonic laser-assisted heating, elucidating how material-dependent absorption, thermal gradients, and fluid flow govern colloidal manipulation under optical excitation [3]. This work unified disparate observations across optical trapping, thermophoresis, and printing, providing a generalized understanding applicable to a wide range of materials and experimental configurations. Advancing toward device integration, George and co-workers demonstrated optically printed plasmonic nanostructures on fiber tips, enabling compact, remote SERS probes capable of chemical sensing and single biological cell analysis, thereby extending optical printing beyond planar substrates to three-dimensional and portable architectures [4]. Addressing scalability and throughput limitations inherent to serial laser printing, the group introduced white light–assisted projection optical printing, where digitally defined patterns are projected to achieve rapid, parallel printing of submicron plasmonic nanostructures over large areas without scanning, significantly improving fabrication speed and design flexibility [5]. This approach was further refined through white-light-driven plasmonic nanoparticle printing, establishing broadband illumination as a viable and simplified alternative to lasers for optothermal manipulation and SERS-active pattern formation [6]. Most recently, the development of continuous bubble-free laser printing resolved a critical limitation of optothermal printing by eliminating vapor bubble formation, enabling uniform plasmonic patterns with annealing-free ohmic conduction while simultaneously supporting multifunctional electrothermal trapping and spectroscopic studies [7]. Collectively, these works position optical printing as a robust, scalable, and multifunctional nanomanufacturing platform, bridging fundamental optothermal physics with practical applications in sensing, diagnostics, and advanced functional surfaces.

1. Monisha K., Bankapur A., Chidangil S., George S. D., Laser-induced assembly of biological cells and colloids onto a candle soot-coated substrate, Colloids and Surfaces A: Physicochemical and Engineering Aspects, 616, 126357 (2021). https://doi.org/10.1016/j.colsurfa.2021.126357

2. Monisha K., Suresh K., Bankapur A., George S. D., Optical printing of plasmonic nanoparticles for SERS and thermophoretic assembly of biological cells, Sensors and Actuators B: Chemical, 377, 133047 (2023).

3. Monisha K., Suresh K., George S. D., Colloidal manipulation through plasmonic and non-plasmonic laser assisted heating, Laser & Photonics Reviews, 2300303 (2023).

4. Monisha K., Suresh K., Bankapur A., George S. D., Optically printed plasmonic fiber tip-assisted SERS-based chemical sensing and single biological cell studies, Analytica Chimica Acta, 1317, 342903 (2024).

5. Bannur B., Monisha K., Shivalingegowda S. M., George S. D., White light-assisted projection printing of submicron plasmonic nanostructures for advanced nanofabrication, Materials Horizons, 12, 4875–4883 (2025).

6. Shivalingegowda S. M., George S. D., White-light-driven plasmonic nanoparticle printing for optothermal manipulation and SERS application, Nanoscale, 17, 23436–23442 (2025).

7. Monisha K., Bannur B., Shivalingegowda S. M., George S. D., Continuous bubble-free laser printing of plasmonic nanostructures enabling annealing-free ohmic conduction and multifunctional trapping/spectroscopy studies, Nanoscale Advances, 7, 8085–8092 (2025).