Session: 12-06-04: Advanced Heat Sinks and Emerging Thermal Applications

Paper Number: 173735

Shrinking Surface Plasmonic Bubble Technique for Ultrasensitive Nanoplastics Detection in Water 

Nanoplastics pose serious environmental and health risks due to their widespread presence in aquatic systems and their potential to penetrate biological membranes, accumulate in food chains, and interfere with physiological processes. Unlike ultrafiltration-based methods, such as pyrolysis-coupled gas chromatography–mass spectrometry (Pyr-GC/MS), which require extensive concentration steps to detect trace amounts of nanoplastics, the Shrinking Surface Bubble Deposition (SSBD) method offers a promising alternative by locally enriching particles through the shrinkage of photothermally generated bubbles. This process leverages Marangoni flow to concentrate suspended nanoplastics onto the bubble surface, which are subsequently deposited on the three-phase contact line after the bubble shrinks and vanishes. To quantify the detection limit of SSBD for nanoplastics in water, 150 nm core–shell gold nanoparticles were employed to enable efficient plasmonic bubble generation and deposition, while also supporting surface-enhanced Raman spectroscopy (SERS) for signal identification. Scanning electron microscopy (SEM) and energy-dispersive x-ray (EDX) spectroscopy were used to visualize the morphology of the nanoplastic particles and confirm their carbon composition, respectively. In the SSBD experiments, testing samples were prepared by mixing a 150 nm core–shell gold nanoparticles suspension with nanoplastic suspensions of various concentrations. The solution was contained in an acrylic cuvette with a glass slide inserted. An 800 nm femtosecond laser was focused onto the surface of the glass slide through a 20× objective lens. The laser was illuminated for several seconds to generate photothermal surface bubbles on the glass substrate. After the surface bubble was generated, it was allowed to grow to approximately 50 μm in diameter before the laser was cut off, and then the bubble started to shrink. Once the bubble shrank and eventually disappeared, suspended plastic and core–shell gold nanoparticles were deposited onto the glass substrate, which was subsequently removed from the solution and dried at room temperature. Results show that the detection limit of SSBD is primarily governed by the size of the target particles: under equal density conditions, smaller particles allow for lower detectable concentrations. For instance, 500 nm polystyrene (PS) particles can be detected at concentrations as low as 10 ng/mL, while 200 nm PS particles can be detected down to 100 pg/mL. Furthermore, the narrowing liquid channel around the plasmonic surface bubble increases the Marangoni flow speed and the probability of trapping nanoplastics at ultralow concentrations, thereby enhancing detection sensitivity. Quantifying the detection limit of SSBD is essential for advancing practical strategies for detecting and monitoring nanoplastics in aquatic environments.

Presenting Author: Yang Liu University of Notre Dame

Presenting Author Biography: Dr. Yang Liu is currently a Postdoctoral Research Associate at the University of Notre Dame, working under the supervision of Prof. Tengfei Luo. His current research focuses on the laser-driven Shrinking Surface Bubble Deposition (SSBD) technique for nanoplastic and biomaterial sensing. He received his Ph.D. in Mechanical Engineering from Northeastern University, USA. His previous research includes far-field and near-field radiative heat transfer, functional photonic metamaterials for non-contact thermal diodes, self-adaptive radiative cooling, and thermophotovoltaic energy harvesting and conversion.

Authors:

Yang Liu University of Notre Dame
Seunghyun Moon University of Notre Dame
Renzheng Zhang University of Notre Dame
Amartya Mandal University of Notre Dame
Eungkyu Lee Kyung Hee University
Tengfei Luo University of Notre Dame