Non-invasive method for detecting a deadly form of malaria

Patent metadata

Field	Value
Publication number	US-11249068-B2
Application number	US-201615774657-A
Country	US
Kind code	B2
Filing date	Nov 9, 2016
Priority date	Nov 9, 2015
Publication date	Feb 15, 2022
Grant date	Feb 15, 2022

Abstract

A non-invasive, continuous, and direct system for detecting the presence of malaria parasites that exploits the paramagnetic properties of hemozoin in red blood cells. An electromagnetic probe (EM probe) is comprised of a dual coaxial coil used to detect iron oxide particles by using sensitive lock-in amplification of detector voltage or phase shift.

First claim

What is claimed is:

1. A system for connecting to an alternating current or power supply for detecting the presence of malaria parasites in blood, comprising:
a probe, in electrical communication with the current or power supply, shaped in a configuration so that it may be hand-held comprising a primary wire and a detector wire, the probe comprising a concentrically wound inner coil configured as the primary wire and outer coil configured as the detector wire, and wherein the inner coil is adapted to produce a magnetic field when a time varying voltage or current is applied to the inner coil, wherein the magnetic field induces a voltage or current in the outer coil through inductive coupling;
a ballast resistor in electrical communication with the inner coil to enable a current on the inner coil to follow the applied time varying voltage or current and to maintain the current on the inner coil substantially constant;
a capacitor in electrical communication with the outer coil;
wherein the ballast resistor and capacitor have predetermined values selected to increase sensitivity of the probe and to reduce noise;
wherein the probe is configured to sense a change in a signal on the detector wire when an iron particle is placed adjacent to the probe;
a measurement system, operably connected to the probe and configured to measure a detectable difference in both phase shift and amplitude change in a voltage or current produced thereby in the detector wire when the primary and detector wires are positioned adjacent to the blood and when there is a presence of iron particles in the blood, the measurement system comprising:
a lock-in amplifier in electrical communication with the probe for extracting the signal on the detector wire; and

wherein sensitivity of the probe is increased by configuring the probe so that the primary wire serves as the inner coil, and the detector wire serves as the outer coil.

2. The system according to claim 1 , wherein the probe is a coaxially wound dual coil wherein the dual coil is placed around a rod of spring steel.

3. The system according to claim 2 , wherein the probe is configured so that a self-inductance of the inner coil is less than 69.6 μH and a self-inductance of the outer coil is less than 475.5 μH.

4. The system according to claim 1 , wherein the self-inductance of the inner coil is about 2.4 μH and the self-inductance for the outer coil is about 4.5 μH.

5. The system according to claim 1 , wherein the system is adapted to detect malaria by detecting the presence of magnetic particles in the blood.

6. The system according to claim 5 , where the magnetic particles are iron rich particles called hemozoin.

7. The system according to claim 1 , wherein the probe and measurement system are configured to detect detectable differences in both phase shift and amplitude change in the voltage or current produced thereby in the detector wire in the presence of iron particles on a scale of less than 44 microns.

8. The system according to claim 7 , wherein the capacitor comprises capacitance between 10 pF and 100 pF and the ballast resistor comprises a ballast resistance between 390 ohms and 2200 ohms.

9. The system according to claim 1 , wherein a diameter of the probe has a predetermined diameter selected to increase sensitivity of the probe.

10. The system according to claim 1 , wherein a diameter of the probe is approximately 1.45 mm.

11. The system according to claim 1 , wherein a diameter of the probe is between 1.25 mm and 1.66 mm.

12. The system according to claim 1 , wherein the probe is comprised of one primary coil and one detector coil.

13. The system according to claim 1 , wherein the ballast resistor comprises a ballast resistance of about 800 ohms and the capacitor comprises a capacitance of about 20 picofarads and wherein a dynamic reserve setting of the lock-in amplifier is set to low.

14. The system according to claim 1 , wherein the malaria parasites comprise Plasmodium falciparum.

15. The system according to claim 1 , wherein both the inner coil and the outer coil are concentrically wound.

16. The system according to claim 1 , wherein the voltage or current produced in the detector wire has at least a first and second duty cycle each comprised of multiple peaks and wherein the primary wire and detector wire has inductances and capacitances so a last peak of the voltage or current produced in the first duty cycle coincides on a sloping side of a first peak of the second duty cycle.

17. The system according to claim 1 , wherein a self-inductance of the inner coil is less than approximately 11.7 μH and a self-inductance of the outer coil is less than approximately 15.1 μH.

18. The system according to claim 1 , wherein the alternating current or power supply is configured to provide a non-sinusoidal, asymmetric signal to the probe.

19. The system according to claim 1 , wherein the lock-in amplifier configured to provide a DC output voltage indicative of a detected phase shift between the voltage or current on the primary wire and the voltage or current produced thereby in the detector wire.

20. The system according to claim 1 wherein the primary wire and detector wire are each comprised of a plurality of layers.

21. A system according to claim 1 , further comprising an alert signal generated by the system when iron particles are detected by the system.

22. A system according to claim 1 , wherein the iron particles are hemozoin.

23. The system of claim 1 , wherein the lock-in amplifier extracts the signal on the detector wire from noise on the detector wire.

24. A system for connecting to an alternating current or power supply for detecting the presence of malaria parasites in blood, comprising:
a probe, in electrical communication with the current or power supply, shaped in a configuration so that it may be hand-held comprising a primary wire and a detector wire, the probe comprising a coaxially wound inner coil configured as the primary wire and outer coil configured as the detector wire, and wherein the inner coil is adapted to produce a magnetic field when a time varying voltage or current is applied to the inner coil, wherein the magnetic field induces a voltage or current in the outer coil through inductive coupling;
a ballast resistor in electrical communication with the inner coil to enable a current on the inner coil to follow the applied time varying voltage or current and to maintain the current on the inner coil substantially constant;
a capacitor in electrical communication with the outer coil;
wherein the ballast resistor and capacitor have predetermined values selected to increase sensitivity of the probe and to reduce noise;
wherein the probe is configured to sense a change in a signal in the detector wire when an iron particle is placed adjacent to the probe;
a measurement system, operably connected to the probe and configured to measure a detectable difference in both phase shift and amplitude change in a voltage or current produced thereby in the detector wire when the primary and detector wires are positioned adjacent to the blood and when there is a presence of iron particles in the blood, the measurement system comprising:
a lock-in amplifier in electrical communication with the probe for extracting the signal on the detector wire;

wherein sensitivity of the probe is increased by configuring the probe so that the primary wire serves as the inner coil, and the detector

Assignees

• Ohio State Innovation Foundation

Inventors

• Subramaniam Vishwanath V
• Drew Mark
• Smith Brad
• West Joseph
• Jones Travis H

Classifications

• G01N2333/445

  Plasmodium · CPC title

• A61B5/14546

  for measuring analytes not otherwise provided for, e.g. ions, cytochromes · CPC title

• G01N33/49 Primary

  Blood {(chemical methods for determining blood cell populations G01N33/5094; chemical analysis of blood groups or blood types G01N33/80)} · CPC title

• A61B5/053

  Measuring electrical impedance or conductance of a portion of the body · CPC title

• Y02A50/30

  Against vector-borne diseases, e.g. mosquito-borne, fly-borne, tick-borne or waterborne diseases whose impact is exacerbated by climate change · CPC title