Microfluidic devices, systems, and methods for quantifying particles using centrifugal force

Abstract

Embodiments of the present invention are directed toward microfluidic systems, apparatus, and methods for measuring a quantity of cells in a fluid. Examples include a differential white blood cell measurement using a centrifugal microfluidic system. A method may include introducing a fluid sample containing a quantity of cells into a microfluidic channel defined in part by a substrate. The quantity of cells may be transported toward a detection region defined in part by the substrate, wherein the detection region contains a density media, and wherein the density media has a density lower than a density of the cells and higher than a density of the fluid sample. The substrate may be spun such that at least a portion of the quantity of cells are transported through the density media. Signals may be detected from label moieties affixed to the cells.

What is claimed is: 
     
         1 . An apparatus for measuring a quantity of particles in a fluid sample, the apparatus comprising:
 a substrate, wherein the substrate at least in part defines a channel;   an inlet port in fluid communication with the channel and configured to receive the fluid sample;   a detection region coupled to the channel and defined at least in part by the substrate and configured to contain a density media, wherein the density media has a density lower than a density of the particles and higher than a density of the fluid sample; and   wherein the channel and the detection region are configured to transport the quantity of particles in the fluid sample from the channel through the density media responsive to a centrifugal force, and wherein at least a portion of the fluid sample is restricted from transport through the density media.   
     
     
         2 . The apparatus of  claim 1 , wherein the substrate comprises a disc. 
     
     
         3 . The apparatus of  claim 1 , further comprising a media reservoir defined at least in part by the substrate and in fluid communication with the detection region, wherein the media reservoir and the detection region are configured such that the density media is transported from the media reservoir to the detection region responsive to a centrifugal force. 
     
     
         4 . The apparatus of  claim 1 , further comprising a label reservoir in fluid communication with the channel, wherein the label reservoir is configured to contain label moieties, and wherein the label moieties are configured to label the quantity of particles. 
     
     
         5 . The apparatus of  claim 1 , wherein the density media comprises a plurality of density medias, and wherein the channel and detection region are further configured to transport the quantity of particles to an interface between the plurality of density medias responsive to a centrifugal force. 
     
     
         6 . A system for measuring a quantity of particles in a fluid, the system comprising:
 a disk comprising:
 a substrate, wherein the substrate at least in part defines a channel; 
 an inlet port in fluid communication with the channel and configured to receive the fluid; 
 a detection region coupled to the channel and defined at least in part by the substrate and configured to contain a density media, wherein the density media has a density lower than a density of the particles and higher than a density of the fluid sample; and 
 wherein the channel and detection region are configured to transport the quantity of particles in the fluid sample from the channel through the density media responsive to a centrifugal force, and wherein at least a portion of the fluid sample is restricted from transport through the density media; 
   a motor coupled to the disk, the motor configured to receive a motor control signal and spin the disk responsive to the motor control signal;   a detection module positioned to detect a signal from label moieties affixed to the quantity of particles, wherein the detection module is configured to generate an electronic detection signal based, at least in part, on the signal from the label moieties; and   a processing device coupled to the motor and the detection module, wherein the processing device is configured to generate the motor control signal and provide the motor control signal to the motor, and wherein the processing device is further configured to receive the electronic detection signal from the detection module.   
     
     
         7 . The system of  claim 6 , wherein the signal from the label moieties comprises an optical signal and wherein the detection module comprises a laser. 
     
     
         8 . The system of  claim 7 , wherein the detection module further comprises an actuator coupled to the laser and the processing device, and wherein the actuator is configured to move the laser along the detection region responsive to an actuator control signal received from the processing device. 
     
     
         9 . The system of  claim 7 , wherein the system further comprises an actuator coupled to the motor, and wherein the actuator is configured to move the disk such that the laser is moved along the detection region responsive to an actuator control signal received from the processing device. 
     
     
         10 . The system of  claim 7 , wherein the processing device is further configured to calculate a number of the quantity of particles based, at least in part, on the electronic detection signal. 
     
     
         11 . The system of  claim 10 , wherein the processing device is configured to integrate at least a portion of the electronic detection signal over time to calculate the number of the quantity of particles.