Sensor device for and a method of sensing particles
A sensor device for sensing particles of a sample, the sensor device including a sensing unit adapted for sensing a detection signal indicative of the presence of the particles, a viscosity measurement unit adapted for measuring the viscosity of the sample, and a correction unit adapted for correcting the detection signal based on the measured viscosity.
1. A sensor device for sensing magnetic particles of a fluidic sample, the sensor device comprising:
a sensing unit configured to sense a detection signal indicative of presence of the magnetic particles;
a viscosity measurement unit configured to measure viscosity of the sample; and
a correction unit for correcting the detection signal based on the measured viscosity, from a predetermined correlation between viscosity and change of the detection signal;
wherein sensing unit comprises a sensing surface, the magnetic particles of the fluidic sample comprise unbound magnetic particles and bound magnetic particles bound to the sensing surface, the viscosity measurement unit is configured to measure the viscosity of the sample using the unbound magnetic particles and the sensing unit is configured to sense the detection signal indicative of the presence of the bound magnetic particles at the sensing surface.
2. The sensor device of claim 1 , further comprising upper and lower portions, wherein the viscosity of the sample is measured by applying a magnetic force to the magnetic particles of the sample located in the upper portion and by vertically moving the magnetic particles of the sample under the influence of the applied magnetic force to measure a time interval until the magnetic particles reach the lower portion.
3. The sensor device of claim 1 , wherein the viscosity measurement unit is configured to measure the viscosity of the sample by applying a magnetic force to the magnetic particles of the sample and by horizontally moving the magnetic particles of the sample under the influence of the applied magnetic force to measure a time interval until the magnetic particles reach a predefined destination.
4. The sensor device of claim 1 , further comprising a viscosity adjustment unit for adjusting the viscosity of the sample to a predefined viscosity value.
5. The sensor device of claim 1 , wherein the viscosity measurement unit is configured to measure the viscosity of the sample by actuation and detection.
6. The sensor device of claim 5 , wherein the actuation is selected from at least one of a magnetic actuation, an optical actuation, and an electrical actuation.
7. The sensor device of claim 5 , wherein the detection is selected from at one of a magnetic detection, an optical detection and an electrical detection
8. The sensor device of claim 1 , wherein the magnetic particles of the fluidic sample comprise unbound magnetic particles and bound magnetic particles and the viscosity of the sample is measured by applying a magnetic field to the sample and by measuring a velocity of the unbound magnetic particles of the sample in response to the applied magnetic field.
9. The sensor device of claim 8 , wherein the velocity of the unbound magnetic particles indicates a time required by the unbound magnetic particles for moving along a predefined distance in the applied magnetic field.
10. The sensor device of claim 8 , further comprising a pair of magnetic field generators having overlapping reaches that are selectively activated by the viscosity measurement unit.
11. The sensor device of claim 10 , further comprising a magnetic sensor disposed adjacent to at least one of the magnetic field generators for detecting transition of the unbound magnetic particles from one magnetic field generator to the other.
12. The sensor device of claim 10 , further comprising two magnetic sensors disposed at opposite sides of the pair of magnetic field generators.
13. The sensor device of claim 1 , wherein the magnetic particles of the fluidic sample comprise unbound magnetic particles and bound magnetic particles and the viscosity of the sample is measured by monitoring at least one of formation and breaking-up of chains of the unbound magnetic particles.
14. The sensor device of claim 13 , further comprising a magnetic field generator for generating a chain-disrupting magnetic field inside the sample for breaking up the chains of the unbound magnetic particles.
15. The sensor device of claim 13 , wherein the sensing unit has a different sensitivity for the presence of the magnetic particles in regions of chain formation than elsewhere.
16. The sensor device of claim 13 , wherein the optical sensor is configured to detect the formation of chains of the magnetic particles via at least one of a change in transmission, reflectance and frustrated total internal reflectance.
17. The sensor device of claim 13 , further comprising a chain-formation magnet for selectively generating a chain-forming magnetic field inside the sample in which chains of the unbound magnetic particles can build up.
18. The sensor device of claim 17 , wherein the chain-formation magnet is adapted to selectively generate chain-forming magnetic fields in at least two different directions.