Droplet evaporation driven assembly of nanoscale objects

Solvent evaporation is a widely used, cost effective method for assembling nanoscale materials into uniformly ordered micro and nano structures over large areas. This technique offers an economical alternative to more expensive manufacturing processes. By carefully controlling the deposition of particles at the three-phase contact line (TPCL) during the evaporation of droplets containing gold nano-colloids, we can create intricate micron and nanoscale structures. The microscale features can be fine-tuned by adjusting the fluid dynamics, the texture of the substrate, and the type of solvent used. On the nanoscale, the arrangement is determined by various interactions between particles and their local concentration. We have explored this droplet evaporation method to design a range of fascinating patterns, such as smectic, hexagonal, vertical arrays, and square lattices, using plasmonic particles of various shapes (spherical, rod-like, cubic) and sizes. These ordered assemblies have potential applications in diverse fields, including biosensing, optoelectronics, printing, and patterning technologies. Additionally, we utilize these structured assemblies to enhance weak Raman signals, improving their use in detection and sensing.

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1. S. Khawas, S. Bhattacharjee, S. Mukherjee, A. Sain, S. Srivastava, Directing the formation of tunable superlattice crystalline phases from anisotropic nanoparticles. Colloids and Surfaces A: Physicochemical and Engineering Aspects 690, 133762 (2024).

2. S. Khawas, S. Srivastava, Anisotropic nanocluster arrays to a diminished zone: different regimes of surface deposition of gold nanocolloids. Soft Matter 19, 3580-3589 (2023).

3. S. Bhattacharjee, S. Srivastava, Ordered stripes to crack patterns in dried particulates of DNA-coated gold colloids via modulating nanoparticle–substrate interactions. Soft Matter 19, 2265-2274 (2023).

4. A. Zaibudeen, S. Khawas, S. Srivastava, Understanding multiscale assembly mechanism in evaporative droplet of gold nanorods. Colloid and Interface Science Communications 44, 100492 (2021).

5. S. Srivastava, Z. A. Wahith, O. Gang, C. E. Colosqui, S. R. Bhatia, Dual-Scale Nanostructures via Evaporative Assembly. Advanced Materials Interfaces 7, 1901954 (2020).