Open Source DIY Optical Tweezers YouTube video by Wfront Principle

We built an open-source DIY optical tweezers setup and turned it into a teaching tool for the lab/classroom. Low-cost, microscope-based optical trapping you can actually build. Curious what you think 👇

www.youtube.com/watch?v=GGlH...

Fabrication and Characterization of Bimetallic Silica-Based and 3D-Printed Active Colloidal Cubes Simulations on self-propelling active cubes reveal interesting behaviors at both the individual and the collective level, emphasizing the importance of developing experimental analogues that allow testing these theoretical predictions. The majority of experimental realizations of active colloidal cubes rely on light actuation and/or magnetic fields to have a persistent active mechanism and lack material versatility. Here, we propose a system of active bimetallic cubes whose propulsion mechanism is based on a catalytic reaction and study their behavior. We realize such a system from synthetic silica cuboids and 3D-printed microcubes, followed by the deposition of gold and platinum layers on their surface. We characterize the colloids’ dynamics for different thicknesses of the gold layer at low and high hydrogen peroxide concentrations. We show that the thickness of the base gold layer has only a minor effect on the self-propulsion speed and, in addition, induces a gravitational torque during sedimentation. For low activity, this gravitational torque orients the particles such that their velocity director is pointing out of the plane, thus effectively suppressing propulsion. We find that a higher active force can remedy the effects of torque, resulting in all possible particle orientations, including one with the metal cap on the side, which is favorable for in-plane propulsion. Finally, we use 3D printing to compare our results to cubes made from a different material, size, and roundness and demonstrate that the speed scaling with increasing particle size originates from the size-dependent drag. Our experiments extend the fabrication of active cubes to different materials and propulsion mechanisms and highlight that the design of active particles with anisotropic shapes requires consideration of the interplay between shape and activity to achieve favorable sedimentation and efficient in-plane propulsion.

Anisotropic active particles cannot always simply turn to change their orientation after having reached a surface: as we show for active colloidal cubes, this can lead to several populations with different particles speeds. Now out in Langmuir! pubs.acs.org/doi/10.1021/...

Nonadditivity in Many-Body Interactions between Membrane-Deforming Spheres Increases Disorder Membrane-induced interactions play an important role in organizing membrane proteins. Measurements of the interactions between two and three membrane deforming objects have revealed their nonadditive ...

There, we didn’t use sticky particles — it makes the experiments much easier to perform. It’s similar to the approach in the paper below:
pubs.acs.org/doi/full/10....
Despite some limitations, the method is experimentally much more straightforward.

By the way, thank you for the very clear and simple explanation in the video. I keep recommending it to people whenever I talk about my PhD work :)

It is super interesting indeed, even for the linear order! Our last piece is still in progress — there we explored different shapes, and yes, we were definitely betting on it :))

Markus Deserno - A Physicist's View on Biological Membranes Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube.

🎥 For more background about this interaction, check out Markus Deserno’s great talk (link below) @markusdeserno.bsky.social

tinyurl.com/3hse4jdj

and the related papers from our group listed:
tinyurl.com/bddhrcax
tinyurl.com/nh9p9bbc
tinyurl.com/38dhasdw

Repulsions and attractions between membrane-deforming spheres, Janus-particles, and opposite tube-like deformations in giant unilamellar vesicles Lipid membrane deformations have been predicted to lead to indirect forces between the objects that induce these deformations. Recent experimental measurements have found an attractive interaction bet...

🔗 Paper link below if you’d like the details.
doi.org/10.1039/d4sm...

🙌 Thanks to @danielajkraft.bsky.social for brilliant work and guidance, and to @leidenphysics.bsky.social for funding the project. Interested in membrane mechanics or how we perform experiments? Feel free to contact me.

💡 What we found
Gentle dents repel bumps, but deeper dents attract them.
The switch happens around a critical curvature—as predicted by theory but never measured before.
Forces are small yet strong enough to steer how curvature-making proteins cluster.

Model system = giant lipid vesicles + membrane adhesive beads + an optical-tweezer-pulled nanotube. Track the bead, map the interaction energy in comparison with thermal motion 🌌➡️🫧

Cell membranes bend when proteins, viruses or nanoparticles stick to them. Two nearby bends “feel” each other through the lipid sheet, a bit like masses interact through curved spacetime. But do they always attract? We set out to measure that directly.

Hello BlueSky.
Hello #Biophotonics.
Hello #OptoFluidics & #MicroRobotics.
@kitkarlsruhe.bsky.social #FLUCS2.0

What type of stage is this? Looks amazing ;)

Spatial atomic layer deposition and it’s magically fast one angstrom per pass!

#ALD #SALD #materialprocessing

Changing your field after your PhD is humbling!

#FeelingSillyEveryday
#LearningSomthingNewEveryday

NWO CHAINS just started! Dealing with optics? I would be happy to chat :)

Mix two motors of opposite polarity with microtubules and they will partition space !
Microtubules will get organized in polar and active barriers, sorting the two motors in separated domains, leading to the emergence of a new type of patterns.
#morphogenesis
doi.org/10.1073/pnas...
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