Self-Contained Handheld Magnetic Platform for Point of Care Cytometry in Biological Samples

Magnetic levitation is a powerful tool capable of distinguishing micrometer-scale particles based on their densities. When a particle is suspended in a paramagnetic medium and placed in a magnetic field formed by two permanent magnets with like poles facing each other, the particle will experience two forces-a magnetic force and a buoyant force. These forces cause a particle, such as a cell, which does not necessarily have magnetic properties, to levitate at a height inversely proportional to its density. Magnetic levitation has been shown to be useful for a range of applications, including disease diagnostics, material characterization, and quality control. Here, a portable, self-contained device fully independent from a dedicated microscope or smartphone is developed to levitate particles of interest, image them using an embedded low-cost optical system and a camera module, and process the captured images in order to estimate the densities of the particles. The device is user-friendly and inexpensive, offering a great potential for rapid, on-site sample analysis such as white blood cell cytometry.