The behavior of microparticles exposed to gravitational and lift forces and to the velocity gradient in flow velocity profile formed in microfluidic conduits is studied from the viewpoint of the transient period (the relaxation) between the moment at which a particle starts to be transported by the hydrodynamic flow and the time at which it reaches an equilibrium position, characterized by a balance of all active forces. The theoretical model allowing the calculation of the relaxation time is proposed. The numerical calculus based on the proposed model is compared with the experimental data obtained under different experimental conditions, namely, for different lengths of microfluidic channels, different average linear velocities of the carrier liquid, and different sizes and densities of the particles used in the study. The results are important for the optimization of microfluidic separation units such as microthermal field-flow fractionation channels in which the separation or manipulation of the microparticles of various origin, synthetic, natural, biological, etc., is performed under similar experimental conditions but by applying an additional thermodynamic force.
- MeSH
- hydrodynamika MeSH
- mikrofluidní analytické techniky MeSH
- velikost částic MeSH
- Publikační typ
- časopisecké články MeSH
The steady-state movement of the spherical and non-spherical particles, such as prolate or oblate rotational ellipsoids, cylinders, or parallelepipeds, suspended in a liquid and exposed to a unidirectional temperature gradient, is analyzed theoretically. The differences in the ratios of the rotational to translational diffusion coefficients of the non-spherical to spherical particles, the heterogeneity of thermal conductivity of the particle body, and the heterogeneity in surface chemical nature make possible to separate the particles according to differences in shape. Preliminary experimental separations of Gram-positive and Gram-negative, nearly spherical and rod-shaped bacteria performed by Microthermal Field-Flow Fractionation confirmed that the fractionation of the cells according to differences in shape is possible.
- Klíčová slova
- chronická lymfocytární leukemie, léčba,
- MeSH
- chlorambucil aplikace a dávkování MeSH
- chronická lymfatická leukemie epidemiologie farmakoterapie MeSH
- epidemiologie MeSH
- financování organizované MeSH
- imunofenotypizace normy MeSH
- incidence MeSH
- lidé MeSH
- monoklonální protilátky aplikace a dávkování MeSH
- prevalence MeSH
- protokoly antitumorózní kombinované chemoterapie aplikace a dávkování MeSH
- stupeň závažnosti nemoci MeSH
- věk při počátku nemoci MeSH
- vidarabin analogy a deriváty aplikace a dávkování MeSH
- Check Tag
- lidé MeSH
The separation of Staphylococcus epidermidis and Rhodococcus erythropolis bacteria was achieved with the use of Micro-Thermal Focusing Field-Flow Fractionation. This is the first performance of separation exploiting the Ludwig-Soret effect (thermal diffusion) of living biological cells, combined with lift forces and resulting in the focusing mechanism of separation. The experiments were carried out under carefully chosen experimental conditions preventing the denaturation of the bacteria.
