System for protecting circuitry in high-temperature environments

• US 20070096863A1
• Filed: 10/31/2005
• Published: 05/03/2007
• Est. Priority Date: 10/31/2005
• Status: Active Grant

• Current Assignee: Codman Neuro Sciences Sarl (Johnson & Johnson)
• Original Assignee: Codman Neuro Sciences Sarl (Johnson & Johnson)
• Inventors: Ginggen, Alec, Valencia Avila, Benito
• Granted Patent: US 7,713,471 B2
• Time in Patent Office: Days
• US Class Current: 338/22.00R
• CPC Class Codes: A61L 2/07 Steam
• CPC Class Codes: A61M 5/14276 specially adapted for implantation
• CPC Class Codes: A61M 60/122 Implantable pumps or pumping devices, i.e. the blood being pumped inside the patient's body
• CPC Class Codes: A61M 60/876 Implantable batteries
• CPC Class Codes: A61N 1/37 Monitoring; Protecting
• CPC Class Codes: H01H 37/72 Switches in which the opening movement and the closing movement of a contact are effected respectively by heating and cooling or vice versa

Abstract

An electrical device for performing a particular function includes a system circuit for performing the function, and a dedicated power supply for providing power to the circuit. Both the system circuit and the power supply are hermetically sealed within a housing. The device within the housing is intended to be sterilized using high temperature, reaching a sterilization temperature. According to the invention, the device includes a thermal switch which is electrically connected between the system circuit and the power supply. The thermal switch is switchable between an open position wherein the system circuit is electrically isolated from the power supply and receives no power therefrom and a closed position wherein the system circuit is electrically connected to the power supply and receives power therefrom. The thermal switch switches from its closed position to its open position in response to the temperature within the housing rising to a predetermined switch-open temperature value. The thermal switch thereafter switches from its open position to its closed position in response to the temperature within the housing cooling to a switch-closed temperature value. With the present invention, the electrical components of a device are automatically protected from thermal damage during sterilization.

Claims

1. An electrical device for performing a particular function, said device being of the type that requires sterilization using heat, said sterilization process reaching a sterilization temperature, said device comprising:

a system circuit for selectively performing said particular function;

a power supply for selectively providing sufficient power to said system circuit to allow said system circuit to perform said particular function;

a housing for containing said system circuit, said housing being hermetically sealed; and

a thermal-switch electrically connected between said power supply and said system circuit, said thermal switch being switchable between an open position wherein said system circuit is electrically isolated from said power supply and receives no power therefrom and a closed position wherein said system circuit is electrically connected to said power supply and receives power therefrom, said thermal switch switching from said closed position to said open position in response to the temperature within said housing rising to a predetermined switch-open temperature value, said thermal switch thereafter switching from said open position to said closed position in response to the temperature within said housing cooling to a switch-closed temperature value, said system circuit when said thermal-switch being in said open position being protected from thermal damage during sterilization.

2. The electrical device, according to claim 1, wherein said housing further contains said power supply.

3. The electrical device, according to claim 1, wherein said power supply is a battery.

4. The electrical device, according to claim 1, wherein said thermal switch includes a bimetallic operator.

5. The electrical device, according to claim 1, wherein said thermal switch includes a controlling circuit.

6. The electrical device, according to claim 1, wherein said housing further includes said thermal switch.

7. The electrical device, according to claim 1, wherein said thermal switch is positioned outside said housing.

8. The electrical device, according to claim 1, wherein said battery is positioned outside said housing.

9. The electrical device, according to claim 1, wherein said thermal switch includes a deformable member made from a shaped-memory-alloy, wherein said member deforms in response to a predetermined change in temperature, said deformation of said member controlling said electrical communication between said power supply and said system circuit.

10. The electrical device, according to claim 1, wherein said thermal switch includes a positive temperature coefficient resistor wherein the resistance of said resistor changes in response to changing temperature.

19. The electrical device according to claim 1, wherein said housing is to be implanted within a human body and said system circuit is designed to interact with the human body.

20. The electrical device according to claim 19, wherein said device is one of the group consisting of an implantable infusion pump and an implantable pace maker.

11. A method for protecting a system circuit during a thermal-based sterilization process, said system circuit being electrically connected to a power supply, and sealed within a housing, a thermal switch being electrically connected between said power supply and said system circuit, in response to said thermal switch reaching a switch-open temperature, said thermal switch electrically switching from an electrically closed condition wherein said system circuit is powered by said power supply to an electrically open condition wherein said system circuit is electrically isolated from said power supply, said thermal switch returning to said closed condition in response to the effecting temperature cooling to a switch-closed temperature, said protection method including the steps of:

heating said housing so that said system circuit heats to said switch-open temperature;

allowing said thermal switch to move to said open condition so that said system circuit becomes electrically isolated from said power supply;

continuing to heat said housing to a higher sterilization temperature; and

maintaining said housing at said sterilization temperature for a predetermined period of time so that said housing and said system circuit become sterilized.

12. The method of protecting a circuit during said thermal-based sterilization process according to claim 11, after the maintaining step, further comprising the steps of:

cooling said housing to said switch-closed temperature; and

allowing said thermal switch to move to said closed condition so that said system circuitry electrically reconnects with said power supply.

13. An electrical device for performing a particular function, said device being of the type that requires sterilization using heat, said sterilization process reaching a sterilization temperature, said device comprising:

a system circuit for selectively performing said particular function;

a power supply for selectively providing sufficient power to said system circuit to allow said system circuit to perform said particular function;

a housing for containing both said system circuit and said power supply, said housing being hermetically sealed; and

a thermal-switch electrically connected between said power supply and said system circuit, said thermal switch being switchable between an open position wherein said system circuit is electrically isolated from said power supply and receives no power therefrom and a closed position wherein said system circuit is electrically connected to said power supply and receives power therefrom, said thermal switch switching from said closed position to said open position in response to the temperature within said housing rising to a predetermined switch-open temperature value, said thermal switch thereafter switching from said open position to said closed position in response to the temperature within said housing cooling to a switch-closed temperature value, said system circuit when said thermal-switch being in said open position being protected from thermal damage during sterilization.

14. The electrical device, according to claim 13, wherein said power supply is a battery.

15. The electrical device, according to claim 13, wherein said thermal switch includes a bimetallic operator.

16. The electrical device, according to claim 13, wherein said thermal switch includes a controlling circuit.

17. The electrical device, according to claim 13, wherein said housing further includes said thermal switch.

18. The electrical device, according to claim 13, wherein said thermal switch includes a deformable member made from a shaped-memory-alloy, wherein said member deforms in response to a predetermined change in temperature, said deformation of said member controlling said electrical communication between said power supply and said system circuit.