👨‍🎓 About me

• I’m a postdoctoral research associate at the University of Minnesota Twin Cities in the Department of Chemical Engineering and Materials Science. My research focuses on interfacial fluid phenomena including liquid-solid, liquid-liquid multiphase flows as well as the effect of rheology involved. For now, I am working on the collapse of an alveolar-sized bubble using a customized microtensiometer, aiming to understand the role of interfacial rheology in the adsorption of lung surfactants onto a monolayer. Out of research, I enjoyed hiking and exploring the food nearby!

🔥 News

• 2025.07: New Acceptance from AICHE🎉🎉 Direct Measurement of Line Tension, Diffusivity, and Young’s Modulus in Lung Surfactant Monolayers Using a Customized Microtensiometer–Confocal Platform
• 2025.07: New Acceptance from AICHE 🎉🎉 Interfacial Morphology Characterization of Lung Surfactants on Curved Surfaces Using Microtensiometer
• 2025.06: New Acceptance from AICHE 🎉🎉 Understanding Limiting Low Surface Tension Behavior and Measuring Line Tension in Lung Surfactant Monolayers
• 2025.02: New Acceptance from ACS 🎉🎉 Adsorption Dynamics and Interfacial Morphology of Lung Surfactant

📝 Publications

• Tran, H., He, Z., & Pack, M. Y. (2025). Microbubble entrainment on thin liquid films under drop impacts. Journal of Colloid And Interface Science (2024) Full text available at {link}.

Figure: Microbubble formation on an inclined oil film

• Boxun Huang, Steven V. Iasella, Meenal Rathi, Joseph Hassler, Clara O. Ciutara, Ziwen He, David C. Morse, and Joseph A. Zasadzinski. (2025). “New experiments and models to describe soluble surfactant adsorption above and below the critical micelle concentration.” Journal of Colloid And Interface Science. Full text available at {link}.

Figure: Characterizing adsorption dynamics of soluble surfactants below and above CMC using Microtensiometer

• He, Z., Tran, H., & Pack, M. Y. (2024). Capillary wave-assisted collapse of non-Newtonian droplets. Physics of Fluids. Full text available at {link}.

Figure: A schematic of the combined RIM-TIRM technique and the droplet impact setup (not to scale)

• Pirdavari, P., Tran, H., He, Z., & Pack, M. Y. (2024). Drainage-induced spontaneous film climbing in capillaries. Physics Review Fluids. Full text available at {link}.

Figure: Schematic and experimental representation of postdrainage dynamics

• Upoma, M. A., He, Z., Tran, H., & Pack, M. Y. (2024). Effects of Dye Addition on the Rheological Properties of Aqueous Polymer Solutions. Langmuir. Full text available at {link}.

Figure: Dripping onto substrate (DoS) setup for light-induced polymer degradation study

• Pirdavari, P., Pourfattah, F., Tran, H., Wang, L., He, Z., & Pack, M. Y. (2024). Experimental and numerical study on the performance index of mixing for low aspect ratio serpentine microchannels. Engineering Research Express. Full text available at {link}.

Figure: Mixing performance at different Dean numbers for the microfluidic channel with the aspect ratio = 0.1

• Ziwen He, Marufa Akter Upoma, and Min Y. Pack. “Dual nature of volatility on drop wetting dynamics of acetone–isopropanol mixtures on ultrathin smooth oil films.” Physics of Fluids 35, no. 1 (2023). Full text available at {link}.

Figure: Wetting dynamics of Acetone-IPA droplets on ultrathin oil films

• Tran, Huy, Ziwen He, Pooria Pirdavari, and Min Y. Pack. “Interplay of Drop Shedding Mechanisms on High Wettability Contrast Biphilic Stripe-Patterned Surfaces.” Langmuir 39, no. 48 (2023): 17551-17559. Full text avaiable at {link}.

Figure: Drop shedding mechanisms on high wettability contrast biphilic stripe-patterned surfaces

• Tran, Huy, Ziwen He, Jordan Sakakeeny, Yue Ling, and Min Y. Pack. “Oscillation dynamics of drops on immiscible thin liquid films.” Langmuir 38, no. 3 (2022): 1243-1251. Full text avaiable at {link}.

Figure: Drop oscillation dynamics with pinned and mobile contact line

• Ziwen He, Huy Tran, and Min Y. Pack. “Air entrainment dynamics of aqueous polymeric droplets from dilute to semidilute unentangled regimes.” Physics of Fluids 34, no. 11 (2022). Full text available at {link}.

Figure: Dependence of interfacial air layer dynamics on the viscoelasticity of impacting droplets

• Ziwen He, Huy Tran, and Min Y. Pack. “Drop bouncing dynamics on ultrathin films.” Langmuir 37, no. 33 (2021): 10135-10142. Full text available at {link}.

Figure: Contact bouncing on ultrathin water films