By introducing geometry-based phoresis kernels, we establish a direct connection between the translational and rotational velocities of a phoretic sphere and the distributions of the driving fields or fluxes. The kernels quantify the local contribution of the field or flux to the particle dynamics. The field kernels for both passive and active particles share the same functional form, depending on the position-dependent surface phoretic mobility. For uniform phoretic mobility, the translational field kernel is proportional to the surface normal vector, while the rotational field kernel is zero; thus, a phoretic sphere with uniform phoretic mobility does not rotate. As case studies, we discuss examples of a self-phoretic axisymmetric particle influenced by a globally-driven field gradient, a general scenario for axisymmetric self-phoretic particle and two of its special cases, and a non-axisymmetric active particle.
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http://dx.doi.org/10.1039/d4sm00360h | DOI Listing |
Soft Matter
December 2024
Mechanical Engineering Department, Birla Institute of Technology and Science, Pilani, Hyderabad Campus, Telangana 500078, India.
Active particles are self-propelling in nature due to the generation of a fore-aft asymmetry in the concentration of solutes around their surface. Both the surface activity and mobility play an important role in the particle dynamics. The solutes are the products of the chemical reaction between the active particle surface and suspending medium.
View Article and Find Full Text PDFNanomaterials (Basel)
November 2024
Université Paris-Saclay, CEA Saclay, CNRS, NIMBE, UMR 3685, LIONS, 91191 Gif-Sur-Yvette CEDEX, France.
This study compares the mobility behaviour, in a HO environment, of three different geometries of hybrid particle made of silica core functionalized by gold (nanoparticles or layer). It is known that the decomposition of HO on gold surfaces drives mobility; however, the link between mobility orientation and the organization of gold on silica surfaces is still questionable. While conventional wisdom posits that asymmetric designs are crucial for generating phoretic forces or localized bubble propulsion, recent research suggests that symmetrical particles may also exhibit motility.
View Article and Find Full Text PDFSoft Matter
November 2024
Department of Mechanical Engineering, University of Hawai'i at Mānoa, 2540 Dole St., Holmes Hall 302, Honolulu, HI 96822, USA.
Many biological microswimmers are capable of chemotaxis, , they can sense an ambient chemical gradient and adjust their mechanism of motility to move towards or away from the source of the gradient. Synthetic active colloids endowed with chemotactic behavior hold considerable promise for targeted drug delivery and the realization of programmable and reconfigurable materials. Here, we study the chemotactic behavior of a Janus particle, which converts "fuel" molecules, released at an axisymmetric chemical patch located on a planar wall, into "product" molecules at its catalytic cap and moves by self-phoresis induced by the product.
View Article and Find Full Text PDFLangmuir
September 2024
Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Manauli 140306, India.
Although cellular transport machinery is mostly ATP-driven and ATPase-dependent, there has been a recent surge in understanding colloidal transport processes relying on a nonspecific physical interaction with biologically significant small molecules. Herein, we probe the phoretic behavior of a biocolloid [composed of a Zn(II)-coordinated metallomicelle and enzymes horseradish peroxidase (HRP) and glucose oxidase (GOx)] when exposed to a concentration gradient of ATP under microfluidic conditions. Simultaneously, we demonstrate that an ATP-independent oxidative biocatalytic product formation zone can be modulated in the presence of a (glucose + ATP) gradient.
View Article and Find Full Text PDFSoft Matter
September 2024
Department of Mechanical Engineering, University of Akron, Akron, OH, USA.
By introducing geometry-based phoresis kernels, we establish a direct connection between the translational and rotational velocities of a phoretic sphere and the distributions of the driving fields or fluxes. The kernels quantify the local contribution of the field or flux to the particle dynamics. The field kernels for both passive and active particles share the same functional form, depending on the position-dependent surface phoretic mobility.
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