title: Motion-based threat detection using microrods: experiments and numerical simulations.
abstract: Motion-based chemical sensing using microscale particles has attracted considerable recent attention. In this paper, we report on new experiments and Brownian dynamics simulations that cast light on the dynamics of both passive and active microrods (gold wires and gold-platinum micromotors) in a silver ion gradient. We demonstrate that such microrods can be used for threat detection in the form of a silver ion source, allowing for the determination of both the location of the source and concentration of silver. This threat detection strategy relies on the diffusiophoretic motion of both passive and active microrods in the ionic gradient and on the speed acceleration of the Au-Pt micromotors in the presence of silver ions. A Langevin model describing the microrod dynamics and accounting for all of these effects is presented, and key model parameters are extracted from the experimental data, thereby providing a reliable estimate for the full spatiotemporal distribution of the silver ions in the vicinity of the source.
authors: Department of Mechanical and Aerospace Engineering, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA. dstn@ucsd.edu.
authors: Barath
authors: B
authors: Ezhilan
authors: Wei
authors: W
authors: Gao
authors: Allen
authors: A
authors: Pei
authors: Isaac
authors: I
authors: Rozen
authors: Renfeng
authors: R
authors: Dong
authors: Beatriz
authors: B
authors: Jurado-Sanchez
authors: Joseph
authors: J
authors: Wang
authors: David
authors: D
authors: Saintillan
mesh_terms: D000393:Air Pollutants / Q000032:analysis; D002623:Chemistry Techniques, Analytical; D004784:Environmental Monitoring; D019216:Metals, Heavy / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D049329:Nanostructures / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods*
chemical_list: D000393:Air Pollutants; D019216:Metals, Heavy