title: Smart-Phone Based Magnetic Levitation for Measuring Densities.
abstract: Magnetic levitation, which uses a magnetic field to suspend objects in a fluid, is a powerful and versatile technology. We develop a compact magnetic levitation platform compatible with a smart-phone to separate micro-objects and estimate the density of the sample based on its levitation height. A 3D printed attachment is mechanically installed over the existing camera unit of a smart-phone. Micro-objects, which may be either spherical or irregular in shape, are suspended in a paramagnetic medium and loaded in a microcapillary tube which is then inserted between two permanent magnets. The micro-objects are levitated and confined in the microcapillary at an equilibrium height dependent on their volumetric mass densities (causing a buoyancy force toward the edge of the microcapillary) and magnetic susceptibilities (causing a magnetic force toward the center of the microcapillary) relative to the suspending medium. The smart-phone camera captures magnified images of the levitating micro-objects through an additional lens positioned between the sample and the camera lens cover. A custom-developed Android application then analyzes these images to determine the levitation height and estimate the density. Using this platform, we were able to separate microspheres with varying densities and calibrate their levitation heights to known densities to develop a technique for precise and accurate density estimation. We have also characterized the magnetic field, the optical imaging capabilities, and the thermal state over time of this platform.
authors: Department of Biomedical Engineering, University of Connecticut, Storrs, CT, 06269, United States of America.
authors: Stephanie
authors: S
authors: Knowlton
authors: Department of Mechanical Engineering, University of Connecticut, Storrs, CT, 06269, United States of America.
authors: Chu Hsiang
authors: CH
authors: Yu
authors: Department of Computer Science and Engineering, University of Connecticut, Storrs, CT, 06269, United States of America.
authors: Nupur
authors: N
authors: Jain
authors: Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, 02115, United States of America.
authors: Ionita Calin
authors: IC
authors: Ghiran
authors: Department of Biomedical Engineering, University of Connecticut, Storrs, CT, 06269, United States of America; Department of Mechanical Engineering, University of Connecticut, Storrs, CT, 06269, United States of America.
authors: Savas
authors: S
authors: Tasoglu
mesh_terms: D004867:Equipment Design; D005682:Gadolinium / Q000737:chemistry; D060526:Magnetic Fields; D010316:Particle Size; D055585:Physical Phenomena; D066330:Printing, Three-Dimensional; D000068997:Smartphone; D013696:Temperature; D013997:Time Factors
chemical_list: D005682:Gadolinium