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"Particle-Free" Magnetic Actuation of Droplets on Superhydrophobic Surfaces Using Dissolved Paramagnetic Salts.
Mats, Lili; Logue, Fiona; Oleschuk, Richard D.
Afiliação
  • Mats L; Department of Chemistry, Queen's University , 90 Bader Lane, Kingston, Ontario K7L 3N6, Canada.
  • Logue F; Department of Chemistry, Queen's University , 90 Bader Lane, Kingston, Ontario K7L 3N6, Canada.
  • Oleschuk RD; Department of Chemistry, Queen's University , 90 Bader Lane, Kingston, Ontario K7L 3N6, Canada.
Anal Chem ; 88(19): 9486-9494, 2016 10 04.
Article em En | MEDLINE | ID: mdl-27605120
Magnetic actuation is a droplet manipulation mechanism in digital microfluidics (DMF), where droplets can be actuated over a (super)hydrophobic surface with a magnetic force. Superparamagnetic particles or ferromagnetic liquids are added to the droplets to provide a "handle" by which the magnet can exert a force on the droplet. In this study, we present a novel method of magnetic manipulation, where droplets instead contain paramagnetic salts with molar magnetic susceptibilities (χm) approximately ≈10 000× < that for superparamagnetic particles. Droplet actuation is facilitated by low surface friction on fluorous silica nanoparticle-based superhydrophobic coatings, where <2 µN is required for reproducible droplet actuation. Different paramagnetic salts with χm from ≈4500 to 72 000 (× 10-6 cm3 mol-1) were used to make aqueous solutions of different concentration and tested for droplet actuation and sliding angle using permanent magnets (1.8-2.1 kG). Paramagnetic salts are compared in terms of solubility, minimum required concentration, and maximum droplet velocity before disengagement. There is a strong correlation between the magnetic susceptibility of the salt solution, its concentration, and ease of actuation. As an application example, droplets containing a paramagnetic salt and doxorubicin (leukemia drug) are magnetically actuated and interrogated using laser-induced fluorescence. Signal attenuation due to the MnCl2 salt was examined, and the Stern-Volmer quenching constant was determined.
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Coleções: 01-internacional Base de dados: MEDLINE Idioma: En Ano de publicação: 2016 Tipo de documento: Article
Buscar no Google
Coleções: 01-internacional Base de dados: MEDLINE Idioma: En Ano de publicação: 2016 Tipo de documento: Article