Single-step centrifugal hematocrit determination on a 10-$ processing device

Abstract

We present a novel concept to process human blood on a spinning polymer disk for the determination of the hematocrit level by simple visual inspection. The microfluidic disk which is spun by a macroscopic drive unit features an upstream metering structure and a downstream blind channel where the centrifugally enforced sedimentation of the blood is performed. The bubble-free priming of the blind channel is governed by centrifugally assisted capillary filling along the sloped hydrophilic side-wall and the lid as well as the special shape of the dead end of the two-layer channel. The hematocrit is indicated at the sharp phase boundary between the plasma and the segregated cellular pellet on a disk-imprinted calibrated scale. This way, we conduct the hematocrit determination of human blood within 5 min at a high degree of linearity (R(2) = 0.999) and at a high accuracy (CV = 4.7%) spanning over the physiological to pathological working range. As all processing steps including the priming, the metering to a defined volume as well as the centrifugation are executed automatically during rotation, the concept is successfully demonstrated in a conventional PC-CDROM drive while delivering the same performance (R(2) = 0.999, CV = 4.3%).

On-chip sample preparations for Point-of-Care cellular analysis of blood

“…The recent advances in the lab-on-a-disk platform for cell analysis were well summarized by Burger et al [60]. Separation of the entire cellular constituent in whole blood can be readily achieved by plasma sedimentation in the lab-ona-disk platform employing straight [61], curved [62], azimuthally inclined [63] and spiral channels [64]. Recently, more and more attention has been drawn to selective separation of target cell populations from whole blood.…”

Centrifugo-Magnetophoretic Purification of CD4+ Cells from Whole Blood Toward Future HIV/AIDS Point-of-Care Applications

“…Lab-on-a-disc strategies have been used in the isolation of macro-fractions of blood such as the hematocrit and plasma. [28][29][30] To further advance the disc strategy, demonstrating that specific cellular phenotypes can also be isolated from medically relevant backgrounds on these systems yet still maintain the amenability to low-cost manufacture and minimal complexity in an associated apparatus is an advantage of lab-on-adisc and of interest to industrial developers. 5 To this end, we examined the ability of our system to isolate the CD4 cellular phenotype from a background of whole blood.…”

Dean flow focusing and separation of small microspheres within a narrow size range

“…Integration of these functions within microfluidics has been demonstrated, employing techniques including sedimentation (Huh et al 2007), centrifugal separation (Riegger et al 2007) and filtration (Prince et al 2007). However, implementation of all these approaches requires relatively high precision, fine and complex geometries.…”