Controlled and Continuous Patterning of Organic and Inorganic Materials by Induced Nucleation in an Optical Tweezers

We demonstrate for the first time controlled patterning by inducing nucleation of material from a dense aqueous dispersion or solution in an optical tweezers. A hot spot is formed on a glass surface by the trapping laser due to which a water vapor bubble is formed causing Gibbs-Marangoni convection of material around the bubble. This results in accretion of material around the bubble, which eventually nucleates into a crystalline state of the material. The nucleation site, when moved by translating the microscope stage of the optical tweezers apparatus, forms a pattern. We have demonstrated the technique using exotic inorganic materials such as soft oxometalates, and organic materials such as glycine, paracetamol, and a fluorescent dye such as perylene. We have written patterns over lengths of nearly 1 mm at the rate of 1 Hz, with best resolution of about 1 micron. The technique has potential for a wide range of applications ranging from solution processed printable electronics to controlled catalysis.