Why do insulating materials exchange electrical charge during contact?
Welcome to the Soft and Complex Materials Lab!
We are a group of experimental scientists working at the intersection of soft matter physics, materials science, complex fluids, and chemistry. Our work spans from the nanoscale to the macroscale, where many of the phenomena we investigate involve surprising phenomena that occur when liquids and solids interact either physically or chemically. An example at a small scale is tribocharging—the exchange of charge between materials during contact—which recent results suggest could arise due to the exchange of hydroxide ions in adsorbed surface water. A macroscale example is non-Newtonian fluid flow in colloidal suspensions. You can find out more about our research, publications, team members and press in the links above!
Our lab has grown again!
In February, Isaac Lenton joined the lab to start building an optical tweezers experiment to levitate micro-meter sized charged particles. By shaking these particles in a strong electric field and precisely monitoring their behavior within the optical trap, we aim to answer questions about how these particles charge and discharge. This experiment will extend the range of particles our group can levitate: already with acoustics we have levitated particles as large as a fruit fly and with optical tweezers we will soon be able to levitate particles as small as the wavelength of visible light.
Dr. Cécile Clavaud has joined the lab in December. She did her PhD with Bloen Metzger and Yoël Forterre in Marseille. Cécile will investigate Quincke rollers: active particles that roll around when subjected to an electrical field. There are so many possibilities when working with active matter, we are very excited to see what we find! We have tons of questions, and Cécile is getting ready to tackle them one at a time.
ERC Starting Grant!
Our lab has been awarded an ERC Starting Grant! The proposal, ‘Tribocharge: a multi-scale approach to an enduring problem in physics,’ is aimed at understanding charge transfer between insulating materials. We’re going to build a comprehensive set of experiments that address all scales involved, ranging from the macroscale all the way atomic-level carriers.
Challenging for sure, but we’re super excited to get to work!
First paper published
Ever wonder about the role of spatial correlations in donor/acceptor properties in same-material tribochcarging? Or whether or not this might be the key to quantitative charge transfer models? If so, look no further than our article in Physical Review Materials!
We show that correlations act as a ‘knob’ to control the amount of charge transfer, while simultaneously affecting the reproducibility of experiments. We also show that such correlations may arise via interactions of the donors/acceptors during the surface formation process, potentially giving clues to what they are.
Thanks to Galien, Seabass, and Juan Carlos for the hard work.
First group outing!
We celebrated our first few months as a research group by going rock climbing! Learning the ropes was relatively easy, but climbing ~40 meters of wall was not… It definitely gives us something to aspire to in terms of improvement. Afterwards we got some pretty tasty burgers at Weinschenke.
Thanks to Galien, Sebastian, and Juan Carlos for a great first few months! Looking forward to all the group outings to come 🙂
First experiment almost running…
Galien is building a setup to precisely study the charge transfer of small (500 micron) particles as they collide against a target. We’ve got the high-speed camera (right), ultrasonic transducer (center), high-power LED (left), massively fast computer (cables), and plenty of Thorlabs legos. All we’re missing is an amplifier… Fingers crossed it arrives soon!
Sebastian Wald is our first rotation student. (He’s the one on the right throwing the shaka sign.) Sebastian is going to perfect our technique for coating nanometric layers of oxide material onto polymer substrates. He will use many different polymers (e.g. PDMS, PVC, PS,…) and depostion techniques (ALD, sputtering). Using EDS, XPS, and AFM, we’ll find which of these combinations makes the most robust samples. Welcome Seabass!
Filling up the lab
While wading through the legal process for some of the bigger purchases, we’ve been stocking up on the basics: tools and electronics! Everything from BNC cables to function generators. Thank goodness for RS Components <3
Dr. Galien Grosjean joins the lab as the first postdoc! Galien did his Ph.D. with Nicolas Vandewalle in Liège. He’s going to do some awesome tribocharging experiments with us (after he cleans up the group office).
Wet lab ready to go!
Many of our experiments require us to prepare samples, which we will do in the wet lab! Equipped with a fume hood and (soon enough) an oven, dessicator, precision balances, glassware, etc., we’ll be able to prepare atomically smooth soft polymers (for tribocharging experiments) or polyacrylimide hydrogels (for elastic leidenfrost experiments). Pretty confident this is the cleanest we’ll ever see this room 🙂
Optical tables set up!
The optical tables are installed! These are going to support the ‘high precision’ half of the lab, where we will build two very exciting experiments. In the first, we’ll use acoustic levitation to measure the charge exchange as small (500 micron) particles collide against a target. In the second, we’ll use optical tweezers to measure the charge of extremely small particles (5 microns) as individual carriers jump on and off. Stay tuned!
High-speed cameras delivered!
The high-speed cameras are here! The Phantom v1612 takes up to 16kfps (!) at 1 GPix resolution. A smaller Veo640L will do 2kfps at 4 GPix, and the ‘basic’ Veo410L does 5kfps at 1 GPix. Can’t wait till everything else gets here so we can start playing with these!
Right now it’s just an ~70 m^2 empty space, but it’s so exciting to think of all the cutting edge physics we’re going to do in here. The rack you see in the center of the image will go above one of the optical tables. Another optical table goes on the other side of the laser curtain to the left, and the area where the photo is take from is the dedicated ‘messy’ experiment side. Now it’s time to fill it up!