Articles by Daniel M. Harris in JoVE
The Diffusion of Passive Tracers in Laminar Shear Flow Manuchehr Aminian1,2, Francesca Bernardi1, Roberto Camassa1, Daniel M. Harris1,3, Richard M. McLaughlin1 1Department of Mathematics, University of North Carolina at Chapel Hill, 2Department of Mathematics, Colorado State University, 3School of Engineering, Brown University A protocol for the study of the diffusion of passive tracers in laminar pressure-driven flow is presented. The procedure is applicable to various capillary pipe geometries.
Other articles by Daniel M. Harris on PubMed
Horizontal Stability of a Bouncing Ball Chaos (Woodbury, N.Y.). Sep, 2016 | Pubmed ID: 27781478 We present an investigation of a partially elastic ball bouncing on a vertically vibrated concave parabolic surface in two dimensions. In particular, we demonstrate that simple vertical motion, wherein the ball bounces periodically at the parabola's vertex, is unstable to horizontal perturbations when the parabolic coefficient defining the surface shape exceeds a critical value. The result is a new periodic solution where the ball bounces laterally over the vertex. As the parabola is further steepened, this new solution also becomes unstable which gives rise to other complex periodic and chaotic bouncing states, all characterized by persistent lateral motion.
Characterization of Tensioned PDMS Membranes for Imaging Cytometry on Microraft Arrays Analytical Chemistry. Apr, 2018 | Pubmed ID: 29510027 Polydimethylsiloxane (PDMS) membranes can act as sensing elements, barriers, and substrates, yet the low rigidity of the elastomeric membranes can limit their practical use in devices. Microraft arrays rely on a freestanding PDMS membrane as a substrate for cell arrays used in imaging cytometry and cellular isolation. However, the underlying PDMS membrane deforms under the weight of the cell media, making automated analytical microscopy (and thus cytometry and cell isolation) challenging. Here we report the development of microfabrication strategies and physically motivated mathematical modeling of membrane deformation of PDMS microarrays. Microraft arrays were fabricated with mechanical tension stored within the PDMS substrate. These membranes deformed 20× less than that of arrays fabricated using prior methods. Modeling of the deformation of pretensioned arrays using linear membrane theory yielded ≤15% error in predicting the array deflection and predicted the impact of cure temperatures up to 120 °C. A mathematical approach was developed to fit models of microraft shape to sparse real-world shape measurements. Automated imaging of cells on pretensioned microarrays using the focal planes predicted by the model produced high quality fluorescence images of cells, enabling accurate cell area quantification (