Massively Parallel Microbubble Nano-Assembly

Abstract

Abstract Microbubbles are an important tool due to their unique mechanical, acoustic, and dynamical properties. While there has been remarkable progress, it remains challenging to generate addressable microbubbles quickly in a parallel and controlled manner. In this work, we present an opto-electrochemical method that combines the precision of light-based imaging with the relatively low energy bubble formation by hydrolysis. In addition, we show that the inclusion of nanoparticles enables individually addressable microbubbles to be formed in designed patterns. The size of the bubbles can be controlled from a few micrometers to over hundred micrometers with a spatial accuracy of ~ 2 - µm. The light intensity required is only ~ 0.1 W/cm2, which is on par with sunlight and several orders of magnitude lower than that required by other state-of-the-art techniques. The technique is general and permits a wide spectrum of particles to be assembled from suspension, ranging from 40-nm silver nanocrystals, 200 nm polymer nanospheres, to 2-µm-E-coli bacterial cells. We demonstrate particle assembly in well-defined patterns, and show how Ag nanoparticle-bacterial-cell arrays can be formed that permit the spectroscopic detection of cell metabolites. Overall, the reported microbubble tool overcomes multiple key challenges in microbubble-based technologies and promises new opportunities in nanomanufacturing, nanophotonic patterning, nanorobotics, biosensing, and single-cell biotechnology.