Capacitive sensor

• US 20080173303A1
• Filed: 01/19/2007
• Published: 07/24/2008
• Est. Priority Date: 01/19/2007
• Status: Active Grant

• Current Assignee: IPG, LLC
• Original Assignee: IPG, LLC
• Inventors: McLaughlin, Patrick L., Decker, Thomas D.
• Granted Patent: US 8,661,910 B2
• Time in Patent Office: Days
• US Class Current: 128/204.23
• CPC Class Codes: A61M 16/00 Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes stimulating the respiratory movement by mechanical, pneumatic or electrical means, iron lungs combined with gas breathing means A61H31/00
• CPC Class Codes: A61M 16/0051 with alarm devices
• CPC Class Codes: A61M 16/024 including calculation means, e.g. using a processor
• CPC Class Codes: A61M 16/0677 Gas-saving devices therefor
• CPC Class Codes: A61M 16/0858 Pressure sampling ports
• CPC Class Codes: A61M 16/0875 Connecting tubes
• CPC Class Codes: A61M 16/12 by mixing different gases
• CPC Class Codes: A61M 16/20 Valves specially adapted to medical respiratory devices
• CPC Class Codes: A61M 2016/0021 with a proportional output signal, e.g. from a thermistor
• CPC Class Codes: A61M 2016/0027 pressure meter
• CPC Class Codes: A61M 2202/0208 Oxygen
• CPC Class Codes: G01L 9/0072 using variations in capacitance

Abstract

A capacitive sensor for measuring pressure comprises a fixed charge plate integral to a printed circuit board, a flexible charge plate that is grounded, a conductive donut-shaped adhesive spacer between the charge plates, a lid, a non-conductive donut-shaped adhesive spacer between the second charge plate and the lid, means of providing a pressure, fixed or variable, to both sides of the flexible charge plate, wherein a microcontroller controls a power supply and provides a voltage to the first charge plate wherein the accumulative voltage may be measured as a means of determining differential pressure.

Claims

1. A capacitive sensor element for differential pressure sensors, comprising:

a first fixed charge plate with a port coupled to a first pressure source;

a flexible charge plate;

means for securely separating the first fixed charge plate and the flexible charge plate wherein the charge plates are an initial distance apart;

means for electrically grounding the flexible charge plate;

a lid with a port coupled to a second pressure source;

means for securely separating the flexible charge plate and the lid;

means for providing a voltage to the first fixed charge plate;

means for measuring an accumulated voltage across the first fixed charge plate and the flexible charge plate for a given amount of time wherein the accumulated voltage is a function of a variable distance between the first charge plate and the flexible charge plate; and

means for calculating the differential pressure based on the change in the initial distance and the variable distance.

2. A capacitive sensor element according to claim 1, further comprising a printed circuit board wherein the first fixed charge plate is integral thereto and an aperture in the printed circuit board is aligned with the first fixed charge plate port;

3. A capacitive sensor element according to claim 2, further comprising a microcontroller which resides on the printed circuit board and wherein the microcontroller includes the means for measuring the accumulated voltage.

4. A capacitive sensor element according to claim 3, further comprising a power source wherein the microcontroller controls the power source to provide a voltage to the first fixed charge plate.

5. A capacitive sensor element according to claim 4, further comprising a resistor through which the microcontroller applies a pulse of voltage.

6. A capacitive sensor element according to claim 2, wherein print circuit board further comprises a means for electromagnetic shielding the first fixed charge plate.

7. A capacitive sensor element according to claim 1, wherein the means for grounding is for the first fixed charge plate and wherein the means for providing a voltage is to the flexible charge plate and wherein the lid further comprises a means for shielding the flexible charge plate.

8. A capacitive sensor element according to claim 1, wherein the flexible charge plate is metalized Mylar.

9. A capacitive sensor element according to claim 1, wherein the means for securely separating the first fixed charge plate and the flexible charge plate is comprised of a first adhesive spacer.

10. A capacitive sensor element according to claim 9, wherein the first adhesive spacer is in electrical contact with the printed circuit board which further comprises the means for grounding the flexible charge plate.

11. A capacitive sensor element according to claim 1, further comprising means for non-conductively masking the first fixed charge plate from the flexible charge plate.

12. A capacitive sensor element according to claim 11, wherein the means for measuring the accumulated voltage resides in the microcontroller.

13. A capacitive sensor element according to claim 12, wherein the microcontroller is measuring an accumulation of voltage more than once for each of the pulses of voltage applied.

14. A capacitive sensor element according to claim 13, wherein the microcontroller measures more than one accumulation of voltage before a pressure is calculated.

15. A capacitive sensor element according to claim 12, further comprising a means of tracking the accumulated voltage in the microcontroller.

16. A capacitive sensor element according to claim 1, wherein the lid is a second fixed charge plate and the means for providing a voltage to the first fixed charge plate further comprises means to provide the voltage to the second charge plates.

17. An oxygen conserving delivery system and operative to regulate a flow of oxygen during an inspiration event of a respiratory cycle based on a calculated differential air pressure, and comprising:

an oxygen source;

a valve assembly including a valve for receiving oxygen from the oxygen source, and having an output port coupled to a respiration tube;

an inspiration sensor resides on a printed circuit board with an aperture, wherein the inspiration sensor includes;

a first fixed charge plate with an aperture affixed to the printed circuit board wherein the first fixed charge plate aperture and the printed circuit board aperture define a port coupled to the respiration tube;

a flexible charge plate;

means for securely separating the first fixed charge plate and the flexible charge plate wherein the charge plates are an initial distance apart;

means for electrically grounding the flexible charge plate;

a lid with an aperture, thereby defining a second inspiration sensor port which is coupled to ambient pressure;

means for securely separating the flexible charge plate and the lid;

means for providing a voltage to the first fixed charge plate;

means for measuring an accumulated voltage across the first fixed charge plate and the flexible charge plate for a given amount of time wherein the accumulated voltage is a function of a variable distance between the first fixed charge plate and the flexible charge plate; and

means for calculating the differential air pressure based on the change in the accumulated voltage at the initial distance and the variable distance;

a microcontroller for regulating operation of the oxygen conserving delivery system, wherein the microcontroller repeatedly receives a variable signal from the inspiration sensor and there from detects an inspiration event; and

a means for regulating a bolus of oxygen supplied to the respiration tube.

18. An oxygen conserving delivery system according to claim 17, wherein the first fixed charge plate is integral the printed circuit board.

19. An oxygen conserving delivery system according to claim 18, further comprising a microcontroller which resides on the printed circuit board and wherein the microcontroller includes the means for measuring the accumulated voltage.

20. An oxygen conserving delivery system according to claim 19, further comprising a power source wherein the microcontroller controls the power source to provide a voltage to the first fixed charge plate.

21. An oxygen conserving delivery system according to claim 20, further comprising a resistor through which the microcontroller applies a pulse of voltage.

22. An oxygen conserving delivery system according to claim 17, wherein the printed circuit board further comprises a means for electromagnetic shielding the first fixed charge plate.

23. An oxygen conserving delivery system according to claim 17, wherein the means for grounding is for the first fixed charge plate and wherein the means for providing a voltage is to the flexible charge plate and wherein the lid further comprises a means for shielding the flexible charge plate.

24. An oxygen conserving delivery system according to claim 17, wherein the flexible charge plate is comprised of metalized Mylar.

25. An oxygen conserving delivery system according to claim 17, wherein means for securely separating the first fixed charge plate and the flexible charge plate is comprised of a first adhesive spacer.

26. An oxygen conserving delivery system according to claim 25, wherein the first adhesive spacer is in electrical contact with the printed circuit board and which further comprises the means for grounding the flexible charge plate.

27. An oxygen conserving delivery system according to claim 17, further comprising means for non-conductively masking the first fixed charge plate from the flexible charge plate.

28. An oxygen conserving delivery system according to claim 17, wherein the means for measuring the accumulated voltage resides in the microcontroller.

29. An oxygen conserving delivery system according to claim 28, wherein the microcontroller is measuring an accumulation of voltage more than once for each of the pulses of voltage applied.

30. An oxygen conserving delivery system according to claim 29, wherein the microcontroller measures more than one accumulation of voltage before an air pressure is calculated by the microcontroller.

31. An oxygen conserving delivery system according to claim 28, further comprising a means of tracking the accumulated voltage in the microcontroller.

32. An oxygen conserving delivery system according to claim 17, wherein the first inspiration sensor port is coupled to ambient pressure, and wherein the second inspiration sensor port is coupled to the valve assembly output port and with the respiration tube.

33. An oxygen conserving delivery system according to claim 17, wherein the system further comprises a barometer for detecting changes in altitude, wherein the barometer provides a signal to the microcontroller and the microcontroller determines when a sufficient change in altitude warrants a modification in oxygen delivery.

34. An oxygen conserving delivery system according to claim 17, wherein the lid is a second fixed charge plate and the means for providing a voltage to the first fixed charge plate further comprises means to provide the voltage to the second charge plates.

35. A capacitive sensor element for absolute pressure sensors, comprising:

a fixed charge plate with a port coupled to a pressure source;

a flexible charge plate;

means for securely separating the fixed charge plate and the flexible charge plate wherein the charge plates are an initial distance apart;

means for electrically grounding the flexible charge plate;

a lid;

means for securely separating the flexible charge plate and the lid;

means for providing a voltage to the fixed charge plate;

means for measuring an accumulated voltage across the fixed charge plate and the flexible charge plate for a given amount of time wherein the accumulated voltage is a function of a variable distance between the first charge plate and the flexible charge plate; and

means for calculating the pressure source.

36. A capacitive sensor element according to claim 35, wherein the fixed charge plate does not have a port and wherein the lid further comprises a port coupled to a pressure source.

37. A capacitive sensor element according to claim 35, wherein the means for grounding is for the first fixed charge plate and wherein the means for providing a voltage is to the flexible charge plate.

38. A capacitive sensor element according to claim 35, wherein the lid further comprises a means for shielding the flexible charge plate.

39. A capacitive sensor element according to claim 35, further comprising means for shielding the fixed charge plate.

40. A method for monitoring respiration, said method comprising the steps of:

(1) providing a respiration monitor which includes a capacitive pressure sensor assembly;

(2) providing mean of controlling the respiration monitor;

(3) providing means of applying a voltage to the capacitive sensor assembly;

(4) providing a means of measuring an accumulated voltage on the capacitive sensor assembly; and

(5) providing a means of determining respiration based on the measuring of the accumulated voltage.

41. The method as defined in claim 40 wherein the means of applying the voltage results in an asymptotic accumulation of voltage on the capacitive sensor assembly.

42. The method as defined in claim 40 wherein the method further comprises more than one measuring of the accumulated voltage.

43. The method as defined in claim 40 wherein the method further comprises applying a pulse of voltage to the capacitive sensor assembly.

44. The method as defined in claim 40 wherein the method further comprises a capacitive sensor assembly with a metalized Mylar charge plate.

45. A method of producing a capacitive pressure sensor assembly, comprising the steps of:

(1) producing a fixed charge plate and a flexible charge plate;

(2) securing and separating the fixed charge plate and the flexible charge plate a first distance apart;

(3) providing means to ground the flexible charge plate;

(4) producing a lid;

(5) securing and separating the flexible charge plate and the lid;

(6) providing means to apply a first pressure to one side of the flexible charge plate and means to apply a second pressure to the other side of the flexible charge plate;

(6) providing means to apply a voltage to the fixed plate;

(7) providing means to measure an accumulated voltage across the fixed charge plate and the flexible charge plate for a given amount of time wherein the accumulated voltage is a function of a variable distance between the fixed charge plate and the flexible charge plate; and

(8) providing means to calculate a differential between the first pressure and the second pressure.

46. The method as defined in claim 45 wherein the method further comprises more than one measuring of the accumulated voltage.

47. The method as defined in claim 45 wherein the method further comprises applying a pulse of voltage to the capacitive sensor assembly.

48. The method as defined in claim 45 wherein the method further comprises a capacitive sensor assembly with a metalized Mylar charge plate.

49. The method as defined in claim 48 further comprising the steps of heating the metalized Mylar charge plate.

50. A method for supplying oxygen to a user'"'"'s respiratory system during a respiration cycle, said method comprising the steps of:

(1) providing an oxygen conserving delivery system which includes a valve assembly, a capacitive inspiration sensor assembly, a microcontroller for positively controlling operation of the valve assembly and the inspiration sensor assembly, and a power source;

(2) providing a pulse of voltage to the capacitive inspiration sensor assembly wherein the accumulation of voltage on the capacitive inspiration assembly is asymptotic;

(3) providing a means of measuring the accumulation of voltage on the capacitive inspiration sensor assembly;

(4) providing a means of determining an inspiration event based on the measuring of the accumulated voltage; and

(5) providing sufficient energy to open a valve of the valve assembly for supplying oxygen to the user.

51. The method as defined in claim 50 wherein the method further comprises more than one measuring of the accumulation of voltage for each of the pulses of voltage provided to the inspiration sensor assembly.

52. The method as defined in claim 50 further comprising the steps of providing a capacitive inspiration sensor assembly comprising:

(1) producing a fixed charge plate and a flexible charge plate;

(2) securing and separating the fixed charge plate and the flexible charge plate a first distance apart;

(3) providing means to ground the flexible charge plate;

(4) producing a lid;

(5) securing and separating the flexible charge plate and the lid;

(6) providing means to apply a first pressure to one side of the flexible charge plate and means to apply a second pressure to the other side of the flexible charge plate;

(6) providing means to apply a voltage to the fixed plate;

(7) providing means to calculate a differential between the first pressure and the second pressure.

53. The method as defined in claim 52 wherein the flexible charge plate is a metalized Mylar.

54. The method as defined in claim 53 further comprising the step of heating the metalized Mylar flexible charge plate.