Collaborative Research: Direct, Nozzle-Free Printing of Functional Nanomaterials Using Ultrasound Bubble Cavitation

点击翻译按钮获取中文摘要

The project aims to provide a robust understanding of the fundamental science behind the working mechanism of a nozzle-free liquid-jetting system. Widely employed state-of-the-art printing techniques rely primarily on the use of nozzles to deposit materials. Nozzles can get clogged, which adversely affects printing reliability and reproducibility. This problem becomes more significant when the nozzle diameter is reduced for high-resolution printing, which is in increasing demand. Additionally, it is difficult to print inks or pastes that contain particles, flakes, and high-aspect ratio nanomaterials. This award supports research to provide knowledge for the development of a nozzle-free additive manufacturing process, which can eliminate clogs and enable narrower jet streams required for high resolution printing. The ultrasound bubble cavitation process enables deposition of different types, shapes, and sizes of nanomaterials on rigid and flexible substrates. The absence of nozzles eliminates clogging problems. Nanomaterial-based additively manufactured devices find a wide range of applications, from electronics to biomaterials to sensors. Therefore, the results from this study benefits the printing industry and the national economy. This project involves several disciplines including applied physics, electrical engineering, mechanical engineering, bioengineering, and materials science. The multi-disciplinary research creates a unique environment, which helps broaden participation of women and underrepresented groups in research and positively impacts engineering education. The project uses YouTube and other social media platforms to disseminate knowledge to a wider community.The project studies a liquid jetting system enabled by a single cavitation bubble created by laser-generated focused ultrasound to print various nanostructures. The ultrasound bubble cavitation printing process is nozzle-less, thus avoiding the clogging problems in existing nozzle-based additive manufacturing techniques. However, a robust understanding of the fundamental mechanism behind the liquid jetting and energy conversion processes involved is needed to realize the full application potential of using this technique for additive manufacturing. To understand the ultrasonic liquid jetting mechanism, the research team develops models of acoustic interference at the air-liquid interface and cavitation zone, laser-flash shadowgraphy to capture the hydrodynamics of bubble formation and jetting, and bubble formation dynamics as a function of varying physical parameters. To design efficient an optoacoustic transducer, the team studies the effect of laser parameters on thermal transport properties in light-absorbing nanocomposite materials leading to high pressure amplitudes, investigates design aspects of photoacoustic lens leading to high focal gain, and fabricates composite lenses and determines the geometric gain, peak pressure amplitude, and lens breakdown factors. Finally, the team prints nanomaterial films, and compares the quality and characteristics of printed films against those obtained with traditional printing systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.