Welcome to my personal webpage!
In this page you will find my research activities.
Liquid jet impacting a droplet
The detailed images of a bullet going through an apple are famous. Similarly spectacular is shooting at a liquid droplet. Not with a bullet, but with a focused liquid jet. The results are valuable for a whole new way of injection, without the need for needles. The liquid is the needle! The experiments of impacting a droplet give information about the speed the liquid jet needs to have for traversing the droplet, which help us in the understanding on how to pierce skin. If you want to know more, please look at the paper published on Soft Matter or the short article by MIT News.
Also please go to my gallery to see some slow-motion videos.
A droplet impacting on solid surfaces is a frequently occurring phenomenon found both in our daily lives and in industrial contexts such as in raindrops, inkjet printing and crop-spraying. Of particular importance is understanding and predicting whether a droplet will splash upon impact, i.e., break into a myriad of secondary droplets, spread over or is adhered onto the surface. Consequently, my studies have been focused on predicting the critical conditions for droplet splash on solid surfaces. This research was published in Physical Review Letters and Scientific Reports. A short description of the findings can be found in Physics Today.
Droplet impact on textiles
Water-repellent clothing is designed to keep water droplets out while letting humidity escape, however our research show that it fails to repel water completely. When a droplet impacts a textile, there are three possible outcomes; no penetration, partial and complete penetration. In the former, the droplet gets captured on the substrate. For partial penetration, the droplet penetrates through the surface, but is sucked back by the droplet on the side of the impact, and the whole liquid volume is retained by the textile. In the latter, the droplet penetrates the substrate, forming liquid fingers at the back of the substrate that eventually break into secondary droplets. We determined a critical pore size delimits the two regimes and is inversely proportional to the impact speed, depending on the droplet size and surface tension. For example, for a typical raindrop, the critical pore size for a fabric to avoid complete penetration is approximately is 100 m. This model can also be applied more broadly for design of textiles to protect against more hazardous liquids. The full paper can be found at Soft Matter and Physics Today.
3D printing of liquid latex
Discarded tires remain one of the major sources of waste of the 21st century. By far the largest proportion of discarded tires end up in landfills, with only a small percentage being recycled. A reason for this, is the lack of suitable recycling methods and ability to make new products with the end-of-life material.
We report a new method to reuse discarded tire waste rubber, by making it a component of 3D printed objects. Using liquid latex, we suspend rubber powder to create a colloidal ink suitable for inkjet-based 3D-printing. The in-house designed acoustic based print-head benefits from a higher material compatibility compared to conventional inkjet/extrusion-based printers, allowing the jetting of the viscous ink across a range of particle loadings. We observe consistent jetting, enabling precise deposition in pre-defined patterns, providing the initial step towards 3D constructs. Moreover, we present a new method of manufacturing with liquid latex. Whilst the developed methods require improvements, such as solidification time, particle size and distribution, the results clearly show the feasibility of the idea as well as providing the foundation for further development. If you want to know more please go to Additive Manufacturing with Liquid Latex and Recycled End-of-Life Rubber | 3D Printing and Additive Manufacturing (liebertpub.com).