Systems and methods for sample verification
The inventive subject matter is directed to point-of-care analytical devices that accurately determine the volume of test samples using image analysis to improve the accuracy of test results performed on the sample. Most preferably, the image analysis is based on rate changes in optical saturation that parallels sample saturation in a porous structure containing the sample.
1. A device for determining a fluid volume contained in a porous structure, comprising:
a holder configured to retain a container having a sample receiving compartment, wherein the porous structure is at least partially disposed in the sample receiving compartment;
a camera configured to take at least one image of the porous structure; and
a controller communicatively coupled to the camera and configured to:
i. detect an area of the porous structure in the at least one image;
ii. divide the area of the porous structure into a plurality of segments;
iii. determine an optical saturation value for each one of the plurality of segments, wherein each of the optical saturation values correlates with a degree of sample saturation of the porous structure; and
iv. calculate, using the optical saturation value of at least one of the plurality of segments of the porous structure, at least one of a sample volume, a sample saturation speed, an indicator of sample quality, and an adjustment correction factor as a function of the optical saturation value and a wicking time of at least one of the plurality of segments; and
an actuator configured to stop a sample from flowing from a sample application location to the porous structure, and wherein the controller is further configured to calculate the sample volume in the porous structure in real time and to trigger the actuator to stop flow when the sample volume reaches a predetermined threshold.
2. The device of claim 1 , wherein the porous structure comprises a round shape.
3. The device of claim 1 , wherein the controller is further configured to determine if an assay should be performed using the fluid volume.
4. The device of claim 1 , wherein the porous structure is deformable such that the porous structure is capable of repeatedly soaking in and expressing out reagents.
5. The device of claim 1 , wherein the sample receiving compartment is at least partially formed from a transparent polymer, and wherein the camera and a light source are positioned relative to the sample receiving compartment to reduce image capture of light reflected off the transparent polymer.
6. The device of claim 1 wherein the controller is configured to process the optical saturation values in a grayscale.
7. The device of claim 1 wherein the controller is configured to determine the optical saturation value for each one of the plurality of segments at least once every 30 s.
8. A controller for correlating a plurality of optical saturation values of an image of a porous structure with a sample volume in the porous structure, the controller comprising:
a processor configured to divide the image into a plurality of segments and to assign respective optical saturation values for each segment for at least a first and second time point;
wherein the processor is further configured to calculate, using differences between the respective optical saturation values for each segment, at least one of: a normalized optical saturation value for each one of the plurality of segments, a sample saturation of each one of the plurality of segments, a saturation speed, an adjustment factor, and an indicator of sample quality; and
wherein the processor is further configured to provide a control signal to an actuator that regulates sample flow into the porous structure upon reaching a predetermined sample saturation in the porous structure.
9. The controller of claim 8 , wherein the processor is further configured to calculate the differences in grayscale.
10. A method of evaluating sample quality comprising:
measuring an optical saturation value from a porous structure at specified time intervals;
determining a saturation rate;
calculating a difference between the change in saturation rate with a reference saturation rate indicative of at least one of an intact sample and a compromised sample;
using the difference between the saturation rate and the reference saturation rate to generate an indicator of sample quality; and
upon determination of the sample quality as being a degraded sample or a compromised sample, canceling the assay or generating an alert.