Manipulation of artificial and living small objects by light driven diffusioosmotic flow

• Published in: Scientific reports Vol. 14; no. 1; pp. 18342 - 13
• Main Authors: Muraveva, Valeriia, Lomadze, Nino, Gordievskaya, Yulia D, Ortner, Philipp, Beta, Carsten, Santer, Svetlana
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 07.08.2024; Nature Publishing Group UK; Nature Portfolio
• Subjects: Chemical speciation; Colloids; Light sources; Microorganisms; Osmotic pressure; Soil microorganisms; Surfactants
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-024-69001-6

Here we report on light-triggered generation of local flow utilizing a bio-compatible non-ionic photo-active surfactant. The mechanism is based on diffusioosmotic phenomenon, where the gradient of relative concentration with respect to different chemical species near a surface leads to an osmotic pressure gradient driving liquid flow along the surface. The application of a photo-responsive surfactant allows for easy and reversible changes in concentration gradient by positioning a light source at the desired place. Along with the so-inscribed concentration gradient one can change reversible the direction and strength of the flow even in a closed system. The phenomenology of light-driven diffusioosmotic flow (LDDO) can be used in a rather flexible way: colloids can be gathered or dispersed and bio-compatibility extends the range of colloid types also to living microorganisms such as soil bacterium Pseudomonas putida. We show that DO flow can be considered a versatile method to set hydrodynamic conditions along the sample for investigating the motility of living cells. Further advantages of employing LDDO are the flexibility of flow generation in a reversible way and with spatiotemporal control, without the need to either change the channel geometry by loading a different device, or the periphery of pumps and connectors.