Sensor with signature of data relating to sensor

• US 20080287757A1
• Filed: 05/06/2008
• Published: 11/20/2008
• Est. Priority Date: 09/28/1999
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Mallinckrodt Incorporated (Mallinckrodt plc)
• Inventors: Fein, Michael E., Mannheimer, Paul D., Porges, Charles E., Olson, Bryan, Berson, Thomas A., Schloemer, David
• Granted Patent: US 8,190,226 B2
• Time in Patent Office: Days
• US Class Current: 600/324
• CPC Class Codes: A61B 2562/08 Sensors provided with means for identification, e.g. barcodes or memory chips
• CPC Class Codes: A61B 2562/085 combined with means for recording calibration data
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: G06F 21/6209 to a single file or object, e.g. in a secure envelope, encrypted and accessed using a key, or with access control rules appended to the object itself
• CPC Class Codes: G06F 21/64 Protecting data integrity, e.g. using checksums, certificates or signatures
• CPC Class Codes: G06F 2211/008 Public Key, Asymmetric Key, Asymmetric Encryption
• CPC Class Codes: G06F 2221/2107 File encryption
• CPC Class Codes: H04L 2209/805 Lightweight hardware, e.g. radio-frequency identification [RFID] or sensor
• CPC Class Codes: H04L 2209/88 Medical equipments
• CPC Class Codes: H04L 9/3247 involving digital signatures

Abstract

A sensor has codes useful for a monitor which can be authenticated as accurate. The sensor produces a signal corresponding to a measured physiological characteristic and provides codes which can be assured of being accurate and authentic when used by a monitor. A memory associated with the sensor stores both data relating to the sensor and a digital signature. The digital signature authenticates the quality of the code by ensuring it was generated by an entity having predetermined quality controls, and ensure the code is accurate.

Claims

1. A pulse oximeter sensor comprising:

an emitter capable of emitting light into tissue;

a detector configured to detect light from the emitter after passing through at least a portion of the tissue and capable of converting the detected light into an electrical signal for use by a monitor; and

a memory storing a digital signature, wherein the digital signature comprises functional data residing completely within the digital signature, the functional data capable of facilitating proper operation of the monitor with the pulse oximeter sensor.

2. The pulse oximeter sensor of claim 1, wherein the functional data comprises a sensor-dependent calibration curve coefficient for use by the monitor to calculate oxygen saturation.

3. The pulse oximeter sensor of claim 1, wherein the functional data comprises information indicative of whether certain components of the data require a specific monitor functionality to be utilized.

4. The pulse oximeter sensor of claim 1, wherein the emitter comprises one or more light emitting diodes.

5. The pulse oximeter sensor of claim 1, wherein the functional data comprises a threshold used to indicate when the sensor is not in proper contact with the tissue.

6. The pulse oximeter sensor of claim 1, wherein the functional data comprises thermistor calibration coefficients appropriate for sensors comprising a thermistor.

7. The pulse oximeter sensor of claim 1, comprising a cable configured to communicatively couple the sensor with the monitor.

8. The pulse oximeter sensor of claim 7, wherein the memory is disposed within the cable.

9. The pulse oximeter sensor of claim 1, comprising a body housing the emitter and the detector.

10. A pulse oximeter comprising:

a processing circuit;

a sensor input configured to receive a signal from a pulse oximeter sensor indicative of a measured physiological characteristic;

a first oximeter memory capable of receiving and storing a digital signature from a sensor memory of the pulse oximeter sensor;

a second oximeter memory capable of storing a signature translation program, the signature translation program capable of cooperating with the processing circuit to verify authenticity of the digital signature and capable of acquiring functional data from the digital signature to facilitate operation of the pulse oximeter with the pulse oximeter sensor; and

an output configured to present data indicative of a value of the measured physiological characteristic based at least in part upon the signal and/or the functional data.

11. The pulse oximeter of claim 10, wherein the first and second oximeter memories comprise different portions of the same physical memory.

12. The pulse oximeter of claim 10, wherein the processing circuit comprises a microprocessor.

13. The pulse oximeter of claim 10, wherein the signature translation program comprises a public key of a private key and public key pair.

14. The pulse oximeter of claim 10, wherein the functional data comprises a sensor-dependent calibration curve coefficient for use by the monitor to calculate oxygen saturation.

15. A method comprising:

receiving a digital signature from the pulse oximeter sensor;

verifying that the digital signature is authentic;

retrieving functional data from within the digital signature;

performing an operation on a signal from the sensor indicative of a physiologic characteristic based at least in part upon the functional data; and

providing an output indicative of a value of the physiological characteristic based at least in part on the signal and/or the functional data.

16. The method of claim 15, comprising determining whether to provide the output based at least in part upon authenticity of the digital signature.

17. The method of claim 15, comprising translating the digital signature to retrieve a sensor-dependent calibration curve coefficient used to calculate oxygen saturation.

18. The method of claim 17, comprising calculating an oxygen saturation value based at least in part upon the sensor-dependent calibration curve coefficient and/or the signal.

19. The method of claim 15, wherein receiving the digital signature from the pulse oximeter sensor comprises communicating with a memory of the pulse oximeter sensor disposed in a cable or a body associated with the pulse oximeter sensor.

20. The method of claim 15, comprising translating the digital signature to retrieve information indicative of whether certain components of the functional data require a specific monitor functionality to be utilized.