Electrodynamic sensors and applications thereof

• US 20060058694A1
• Filed: 12/09/2002
• Published: 03/16/2006
• Est. Priority Date: 12/07/2001
• Status: Active Grant

• Current Assignee: University of Sussex
• Original Assignee: University of Sussex
• Inventors: Prance, Robert J, Harland, Christopher J, Clark, Terence D
• Granted Patent: US 7,885,700 B2
• Time in Patent Office: Days
• US Class Current: 600/509
• CPC Class Codes: A61B 5/30 Input circuits therefor
• CPC Class Codes: A61B 5/308 for electrocardiography [ECG]
• CPC Class Codes: A61B 5/31 for electroencephalography [EEG]
• CPC Class Codes: A61B 5/313 for electromyography [EMG]
• CPC Class Codes: A61B 5/315 for electrooculography [EOG]; for electroretinography [ERG]
• CPC Class Codes: G01R 29/12 Measuring electrostatic fields or voltage-potential
• CPC Class Codes: G01R 5/28 Electrostatic instruments

Abstract

An electrodynamic sensor comprises a high input impedance electrometer adapted to measure small electrical potentials originating from an object under test and having a pair of input probes, characterised in that at least one of said pair of input probes has no direct electrical contact with said object, wherein the circuit arrangement of said electrometer comprises an amplifier which includes a combination of ancillary circuits cumulatively to increase the sensitivity of said electrometer to said small electrical potentials whilst not perturbing the electrical field associated therewith.

Claims

1. An electrodynamic sensor comprising a high input impedance electrometer adapted to measure small electrical potentials originating from an object under test and having a pair of input probes, characterised in that at least one of said pair of input probes has no direct electrical contact with said object, wherein the circuit arrangement of said electrometer comprises an amplifier which includes a combination of ancillary circuits cumulatively to increase the sensitivity of said electrometer to said small electrical potentials whilst not perturbing the electrical field associated therewith.

3. An electrodynamic sensor according to claim 1 characterised in that it includes ancillary circuits to provide at least two of guarding, bootstrapping, neutralisation, supply rail drift correction, supply modulation and offset correction for said sensor.

13. An electrodynamic sensor according to claim 1 characterised in that a differential signal from two probes is utilised to reduce the effect of undesired noise signals.

14. An electrodynamic sensor according to claim 1 characterised in that multiple probes, arranged in linear or higher dimensional areas are used to produce dynamic potential line profiles or maps to measure or display the electrical activity on the surface of a body or from a location within said body.

15. An electrodynamic sensor according to any claim 1 characterised in that a single probe is scanned over a linear or higher dimensional areas to produce dynamic potential line profiles or maps to measure or display the electrical activity on the surface of a body or from a location within said body.

16. An ambulatory monitor for electrocardiograms, electroencephalograms or electrooculograms including an electrodynamic sensor according to claim 1.

17. An array imaging device including an electrodynamic sensor according to claim 1.

18. A catheter probe including an electrodynamic sensor according to claim 1.

19. A detector for nerve muscle (EMG) or other biodynamic signals including an electrodynamic sensor according claim 1.

20. An artificial limb including an electrodynamic sensor according to claim 1.

21. Remote sensing apparatus for proximity detection or control including an electrodynamic sensor according to claim 1.

22. A machine interfaces for a vital body to implement control functions directly and/or apply biofeedback including an electrodynamic sensor according to claim 1.

23. Apparatus for impedance tomography including an electrodynamic sensor according to claim 1.

24. Apparatus for geophysical surveying including an electrodynamic sensor according to claim 1.

25. Apparatus for crack and corrosion detection of metal structures including an electrodynamic sensor according to claim 1.

26. Apparatus for detection of movement of dielectric objects in a static electric field including an electrodynamic sensor according to claim 1.

27. Apparatus for monitoring of voltages generated by rocks under stress including an electrodynamic sensor according to claim 1.

28. Apparatus for remote capacitive measurements including an electrodynamic sensor according to claim 1.

29. Apparatus for measuring properties of liquid systems or mixtures by immersion of insulating electrodes including an electrodynamic sensor according to claim 1.

31. A signal output system for an electronic device including an electrodynamic sensor according to claim 1.

32. A detector for non-contact detection of signals or signal propagation within a neural network including an electrodynamic sensor according to claim 1.

33. A probe for use with nuclear magnetic resonance or nuclear quadrupole resonance including an electrodynamic sensor according to claim 1.

34. A monitor for single cell biology including an electrodynamic sensor according to claim 1.

35. A monitor for measuring the electrical activity due to single nerve or muscle fibres including an electrodynamic sensor according to claim 1.

36. A smart card including an electrodynamic sensor according to claim 1.

37. A body status monitor including an electrodynamic sensor according to claim 1.

38. An electrocardiogram (ECG) and electroencephalogram (EEG) or electro-oculogram (EOG) produced using an electrodynamic sensor according to claim 1.

39. A method of sensing electrical activity using an electrodynamic sensor according to claim 1.

2. An electrodynamic sensor including a high input impedance electrometer having a pair of probes for the detection of small electrical potentials originating from a body under test characterised in that there is no direct electrical contact between at least one of said pair of probes and said body.

11. An electrodynamic sensor for sensing electrical activity of a vital body according to claim 2 characterised in that it includes an electrode with a guarded coaxial structure.

12. An electrodynamic sensor for sensing electrical activity of a vital body according to claim 11 characterised in that it includes an electrode with a planar tri-plate configuration, with the measurement electrode sandwiched between two guard planes.

4. An electrodynamic sensor for sensing electrical activity of a vital body characterised in that it includes probes which are not in direct conductive contact with said vital body thereby maintaining non-invasive, electrically isolated operation.

5. An electrodynamic sensor for sensing electrical activity of a vital body according to claim 4 characterised in that said sensor is usable to monitor said electrical activity by means of non-invasive, electrically isolated probes in either a contact mode or a remote off-body mode.

6. An electrodynamic sensor for sensing electrical activity of a vital body according to claim 4 characterised in that a capacitive coupling is used for efficient signal transfer from the body to the first stage of the electrometer amplifier.

7. An electrodynamic sensor for sensing electrical activity of a vital body according to claim 6 characterised in that said capacitative coupling comprises an air gap between the body being measured and the sensor.

8. An electrodynamic sensor for sensing electrical activity of a vital body according to claim 7 characterised in that the capacitative coupling comprises a disc electrode with a thin film of insulating material. The oxide thickness is chosen to provide the capacitance required, given the sensor surface area and sensor disc material (substrate).

9. An electrodynamic sensor for sensing electrical activity of a vital body according to claim 8 characterised in that said film comprises an anodised oxide film.

10. An electrodynamic sensor for sensing electrical activity of a vital body according to claim 8 characterised in that the thickness of said thin film is of the order of 1 μ

m.

30. Apparatus for scanning integrated circuits to produce an image thereof including an electrodynamic sensor according to any 1.