Wetness sensor

• US 7,605,710 B2
• Filed: 08/18/2006
• Issued: 10/20/2009
• Est. Priority Date: 08/18/2006
• Status: Active Grant

• Current Assignee: Fresenius Medical Care Holdings Incorporated (Fresenius SE & Co. KGaA)
• Original Assignee: Fresenius Medical Care Holdings Incorporated (Fresenius SE & Co. KGaA)
• Inventors: Levin, Roland, Crnkovich, Martin, Christensen, Peter
• Primary Examiner(s): Pham; Toan N
• Assistant Examiner(s): McNally; Kerri L
• Application Number:
  US11/506,602
• Publication Number:
  US 20080041792A1
• Time in Patent Office: 1,159 Days
• Field of Search: 340/604
• US Class Current: 340/604
• CPC Class Codes: A61F 13/42 with wetness indicator or alarm
• CPC Class Codes: A61M 1/3656 Monitoring patency or flow at connection sites; Detecting disconnections
• CPC Class Codes: A61M 1/367 Circuit parts not covered by the preceding subgroups of group A61M1/3621
• CPC Class Codes: A61M 2205/13 with means for the detection of operative contact with patient, e.g. lip sensor
• CPC Class Codes: A61M 2205/15 Detection of leaks
• CPC Class Codes: A61M 2205/3561 local, e.g. within room or hospital
• CPC Class Codes: A61M 2205/3592 using telemetric means, e.g. radio or optical transmission

Abstract

The present invention relates to a wetness detector system that rapidly detects the presence of wetness due to a liquid leak in a system. The wetness detector system contains a reusable wetness sensor that is able to accurately detect the presence of wetness and, in the case of an extracorporeal blood treatment, the presence of blood. The wetness detector system can quickly alert both a user and medical personnel that a liquid leak has been detected in a treatment system and, if necessary, halt the removal of liquids and/or blood from the patient. If a liquid leak is not detected for a period of time, the wetness sensor can enter a low power state, extending the life of the device. The wetness detector system can monitor a number of wetness sensors simultaneously, which would, for example, eliminate the need for medical personnel to continuously inspect numerous patients visually for potentially fatal blood leaks due to needle dislodgement during an extracorporeal blood treatment.

Claims

1. A wetness detector system for detecting a liquid leak in an extracorporeal blood treatment system comprising:

a wetness sensor comprising;

a solid support comprised of a non-electrically conductive material having first and second surfaces,

an electronic transmitter on the first surface of said solid support,

a trace antenna coupled to said electronic transmitter printed on said first surface of said solid support, for sending a signal via said antenna,

a power source connected to said electronic transmitter,

an open electric circuit connected to said power source and printed on said second surface of said solid support for detecting the presence of wetness,

said electric circuit comprised of two electrodes comprised of one or more electrically conductive materials, wherein exposure of said electric circuit of said wetness sensor to moisture closes the electric circuit and generates a detectable electrical signal,

a microcontroller in communication with said electronic transmitter and said electric circuit, wherein said electrical signal is received by said microcontroller and said microcontroller determines whether the signal is greater than a predetermined wetness detection threshold value, wherein a wetness detection threshold value greater than the predetermined value indicates the presence of a liquid leak, and wherein in response to an indication that a liquid leak has occurred, said microcontroller directs said electronic transmitter to transmit at least one signal that a liquid leak has been detected,

a voltage detection device coupled to said power source and in communication with said microcontroller for detecting a low power supply of said power source; and

an attachment device for attaching said wetness sensor to one or more components of the system; and

a receiver unit integrated with an extracorporeal blood treatment system operation unit, in communication with said wetness sensor comprising;

a receiver for detecting one or more signal transmissions from said wetness sensor,

a controller that controls the extracorporeal blood treatment system operation unit, in communication with said receiver, said controller being capable of discontinuing operation of the extracorporeal blood treatment system upon said receiver detecting one or more signal transmissions from said wetness sensor indicating that a liquid leak has occurred, and

an alert system comprised of one or more alarms selected from the group consisting of the display of a warning message, an audible alarm, and a visual alarm, in communication with said controller, wherein the transmission from the wetness sensor of at least one signal of a liquid leak is received by said receiver of the receiver unit and, in response to said at least one signal, said controller of the receiver unit triggers said alert system, and wherein the receiver unit is in communication with one or more wetness sensors, wherein each of the one or more wetness sensors transmits unique identification information to said receiver of the receiver unit that is recorded by said controller of the receiver unit.

2. The wetness detector system of claim 1, wherein the wetness sensor is attached to one or more liquid lines of the extracorporeal blood treatment system.

3. The wetness detector system of claim 2, wherein the wetness sensor is attached to one or more liquid lines selected from the group consisting of a hydraulic hose, a line for carrying dialysate, and a line for carrying blood.

4. The wetness detector system of claim 1, wherein the wetness sensor is attached to an absorbent material surrounding a needle insertion site.

5. The wetness detector system of claim 1, wherein said microcontroller directs the wetness sensor to enter a low power state for a specified amount of time when no detectable electrical signal is generated during a specific interval of time.

6. The wetness detector system of claim 1, wherein the one or more wetness sensors are further comprised of a wetness sensor receiver and the receiver unit is further comprised of a receiver unit transmitter.

7. The wetness detector system of claim 6, wherein the receiver unit transmitter transmits at every specified interval of time a functionality test signal to the one or more wetness sensors that is received by said wetness sensor receiver and, in response to said signal, the wetness sensor transmits a functionality confirmation signal back to the receiver unit, thereby indicating that the wetness sensor is functional.

8. The wetness detector system of claim 7, wherein the wetness sensor is functional and wherein in response to a lack of transmission of at least one signal of a liquid leak from the one or more wetness sensors during a specific interval of time, the receiver unit transmits a signal to the wetness sensor directing the wetness sensor to enter a low power state for a specified amount of time.

9. The wetness detector system of claim 1, wherein the alert system is reset after one or more selected from the group consisting of the controller is instructed by an external operator to halt the one or more alarms, and moisture is removed from the wetness sensor surface.

10. The wetness detector system of claim 9, wherein the power source of the wetness sensor is one or more batteries.

11. The wetness detector system of claim 10, wherein the microcontroller triggers a low battery alarm when the voltage detected by said voltage detection device is less than a specified voltage, wherein the presence of wetness is not indicated by the wetness sensor.

12. The wetness detector system of claim 11, wherein the low battery alarm is integrated with the receiver unit and is comprised of an audible alarm, a visual alarm or a combination thereof, wherein the low battery alarm differs from the one or more alarms of the alert system.

13. The wetness detector system of claim 12, wherein the microcontroller directs the electronic transmitter to transmit at least one signal to the receiver unit that the voltage of the battery is low and, in response to said at least one signal, the receiver directs the controller to trigger said low battery alarm.

14. The wetness detector system of claim 1, wherein the wetness sensor is further comprised of an illumination device attached to said second surface of the wetness sensor solid support for detecting a presence of blood, the illumination device connected to said power source and in communication with said microcontroller.

15. The wetness detector system of claim 14, wherein the illumination device is comprised of a light emitter and a wavelength-calibrated photodiode detector.

16. The wetness detector system of claim 15, wherein in response to an indication that wetness is present the microcontroller directs the light emitter to produce visible light, wherein a wavelength detected by said photodiode of between about 520 nanometers (nm) and 610 nm indicates that the wetness present is blood.

17. The wetness detector system of claim 15, wherein in response to an indication that wetness is present the microcontroller directs the light emitter to produce near-infrared light, wherein a wavelength detected by said photodiode of between about 740 nm and 820 nm indicates that the wetness present is blood.

18. The wetness detector system of claim 17, wherein in response to a lack of indication that the wetness present is blood during a specific interval of time, the microcontroller directs the wetness sensor to enter a low power state for a specified amount of time.

19. The wetness detector system of claim 18, wherein in response to an indication that the wetness present is blood, said microcontroller directs said electronic transmitter to transmit at least one signal that a needle insertion site blood leak has been detected.

20. A wetness detector system for detecting a liquid leak in an extracorporeal blood treatment system comprising:

one or more wetness sensors each comprising;

a solid support comprised of a non-electrically conductive material having first and second surfaces,

an electronic transmitter on the first surface of said solid support,

a trace antenna coupled to said electronic transmitter printed on said first surface of said solid support,

a power source including one or more batteries connected to said electronic transmitter,

an open electric circuit connected to said power source and printed on said second surface of said solid support for detecting the presence of wetness,

said electric circuit comprised of two electrodes comprised of one or more electrically conductive materials, wherein exposure of said electric circuit of said wetness sensor to moisture closes the electric circuit and generates a detectable electrical signal,

a microcontroller in communication with said electronic transmitter and said electric circuit, wherein said electrical signal is received by said microcontroller and said microcontroller determines whether the signal is greater than a predetermined wetness detection threshold value, wherein a wetness detection threshold value greater than the predetermined value indicates the presence of wetness, and wherein in response to an indication that wetness is present, said microcontroller directs said electronic transmitter to transmit at least one signal that a liquid leak has been detected,

a voltage detection device coupled to said power source and in communication with said microcontroller for detecting a low power supply of said power source, wherein the microcontroller triggers a low battery alarm when the voltage detected by said voltage detection device is less than a specified voltage, wherein the presence of wetness is not indicated by the wetness sensor; and

an attachment device for attaching said wetness sensor to one or more components of the system; and

a receiver unit integrated with an extracorporeal blood treatment system operation unit, the extracorporeal blood treatment selected from the group consisting of oxygenation, detoxification, transfusion, and filtration, in communication with one or more of said wetness sensors,

said receiver unit comprising;

a receiver for detecting one or more signal transmissions from said one or more wetness sensors,

a controller that controls the extracorporeal blood treatment system operation unit, in communication with said receiver, wherein each of the one or more wetness sensors transmits unique identification information to said receiver of the receiver unit that is recorded by said controller of the receiver unit, and

an alert system comprised of one or more alarms selected from the group consisting of the display of a warning message, an audible alarm, and a visual alarm, in communication with said controller, wherein the transmission from the one or more wetness sensors of at least one signal of a liquid leak is received by said receiver of the receiver unit and, in response to said at least one signal, said controller of the receiver unit triggers said alert system and directs the extracorporeal blood treatment system to stop one or more pumps or close one or more blood line valves of the system, and wherein the alert system is reset after one or more selected from the group consisting of the controller resets one or more alarms, and moisture is removed from the wetness sensor surface.

21. The wetness detector system of claim 20, wherein said microcontroller directs the wetness sensor to enter a low power state for a specified amount of time when no detectable electrical signal is generated during a specific interval of time.

22. The wetness detector system of claim 21, wherein the two electrodes of the electric circuit are comprised of one or more electrically conductive materials selected from the group consisting of a metal, polymer, silicon, and carbon.

23. The wetness detector system of claim 22, wherein the low battery alarm is integrated with the receiver unit and is comprised of an audible alarm, a visual alarm or a combination thereof, wherein the low battery alarm differs from the one or more alarms of the alert system.

24. The wetness detector system of claim 23, wherein the microcontroller directs the electronic transmitter to transmit at least one signal to the receiver unit that the voltage of the battery is low and, in response to said at least one signal, the receiver directs the controller to trigger said low battery alarm.