Bubble‐pen lithography: Fundamentals and applications

Abstract

Developing on-chip functional devices requires reliable fabrication methods with high resolution for miniaturization, desired components for enhanced performance, and high throughput for fast prototyping and mass production. Recently, laser-based bubble-pen lithography (BPL) has been developed to enable sub-micron linewidths, in situ synthesis of custom materials, and on-demand patterning for various functional components and devices. BPL exploits Marangoni convection induced by a laser-controlled microbubble to attract, accumulate, and immobilize particles, ions, and molecules onto different substrates. Recent years have witnessed tremendous progress in theory, engineering, and application of BPL, which motivated us to write this review. First, an overview of experimental demonstrations and theoretical understandings of BPL is presented. Next, we discuss the advantages of BPL and its diverse applications in quantum dot displays, biological and chemical sensing, clinical diagnosis, nanoalloy synthesis, and microrobotics. We conclude this review with our perspective on the challenges and future directions of BPL.

Multifunctional Laser-Induced Bubble Microresonator for Upconversion Emission Enhancement

“…The temperature gradient produced around the localized plasmonic heating area, resulting in the convective flow of nanomaterials toward the microbubble due to strong Marangoni convection. 27,42 The size of the bubble can be controlled by the irradiation time. The spherical symmetry offered by the bubble provides optical WGMs suitable for photoluminescence enhancements.…”

“…The bubble microresonator formed in this case was due to the localized heating around Ag NPs trapped by the 800 nm laser on the glass surface via plasmonic optothermal effect. , The Ag NP aggregates can couple together to produce new plasmonic resonant modes close to the 800 nm laser irradiation. − The plasmonic heating raised the temperature close to the kinetic limit of superheat at roughly constant pressure, leading to the evaporation of the solvent and the formation of a bubble. The temperature gradient produced around the localized plasmonic heating area, resulting in the convective flow of nanomaterials toward the microbubble due to strong Marangoni convection. , The size of the bubble can be controlled by the irradiation time. The spherical symmetry offered by the bubble provides optical WGMs suitable for photoluminescence enhancements.…”

“…Figure c shows the bubble microresonator size as a function of the intensity of the 800 nm laser, which was used for inducing the bubble. Higher laser powers increase the size of the bubble due to excessive plasmonic heating of the solvents around aggregates of Ag NPs. , Figure d shows the dark-field images of the bubble microresonator increasing in size with larger laser intensities. Additionally, when the bubble microresonator bursts eventually, it leaves behind the Ag NPs over the PMMA/UCNP films (SC2).…”

“…Additionally, when the bubble microresonator bursts eventually, it leaves behind the Ag NPs over the PMMA/UCNP films (SC2). The bubble microresonator then works well toward depositing Ag NPs over the substrate in a controlled manner, i.e., laser-induced bubble-pen lithography or bubble printing. , Figure e shows the dark-field images of printing Ag NPs over PMMA/UCNP film by laser-induced bubbles. The imprinting or assembling of Ag NPs onto the PMMA/UCNP films is relevant to various biological, physical and chemical applications. , …”

“…This platform provides upconversion emissions enhancement by the resonant plasmonic Ag NPs along with the optical WGMs offered by the bubble microresonator, which enhances the emissions from the UCNPs by over 200 times in comparison to only UCNP. In addition, the growth and gradual disintegration of the bubble imprints the Ag NPs onto the PMMA/UCNP film, which can serve as the bubble-pen lithography 27 for obtaining patterns of metallic NPs over the UCNP film. The multiple roles of microbubbles are suitable for making multifunctional devices to fulfill the present sustainable technological needs.…”