Methods, Devices, and Systems Which Determine a Parameter Value of an Object or an Environment From a Voltage Reading Associated With a Common Mode Signal of a Balanced Circuit

• US 20140023112A1
• Filed: 07/18/2012
• Published: 01/23/2014
• Est. Priority Date: 07/18/2012
• Status: Active Grant

• Current Assignee: Millar Instruments
• Original Assignee: Millar Instruments
• Inventors: Millar, Huntly D., Pauly, Robert L., Thornton, Richard T.
• Granted Patent: US 9,429,479 B2
• Time in Patent Office: Days
• US Class Current: 374/143
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• CPC Class Codes: A61B 2562/0271 Thermal or temperature sensors
• CPC Class Codes: A61B 2562/029 Humidity sensors
• CPC Class Codes: A61B 5/1073 Measuring volume, e.g. of limbs
• CPC Class Codes: A61B 5/11 Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb for measuring pulse A61B5/02 ;A61B5/1038 takes precedence; motion detection to correct for motion artifacts in physiological signals A61B5/721
• CPC Class Codes: A61B 5/14539 for measuring pH
• CPC Class Codes: A61B 5/14542 for measuring blood gases A61B5/14551 takes precedence
• CPC Class Codes: G01K 13/20 Clinical contact thermometers for use with humans or animals
• CPC Class Codes: G01K 7/20 in a specially-adapted circuit, e.g. bridge circuit
• CPC Class Codes: G01L 1/2262 involving simple electrical bridges
• CPC Class Codes: G01L 1/2281 for temperature variations
• CPC Class Codes: G01L 9/045 with electric temperature compensating means non electric temperature compensating means G01L19/04
• CPC Class Codes: G01L 9/065 with temperature compensating means non electric temperature compensating means G01L19/04
• CPC Class Codes: G01R 17/10 AC or DC measuring bridges

Abstract

A method for determining a value of a parameter of an object or an environment includes positioning a device having a balanced circuit in or on an object or within a particular environment, wherein the balanced circuit comprises elements which are operationally sensitive to changes in a parameter of the object or the environment. The method further includes measuring a common mode signal of the balanced circuit and determining, from the common mode signal, a value of the parameter. An exemplary implementation of the method includes determining temperature using a resistive sensor having a Wheatstone bridge circuit with two variable resistors and two fixed resistors. Embodiments of systems and devices configured to employ such methods are provided, particularly medical probes, electronic signal monitoring devices, and systems employing such devices.

Claims

1. A method for determining a value of a parameter of an object or an environment, wherein the method comprises:

positioning a device having a balanced circuit in or on an object or within a particular environment, wherein the balanced circuit comprises elements which are operationally sensitive to changes in a parameter of the object or the environment;

measuring a voltage derived from the balanced circuit which correlates to a common mode signal of the balanced circuit; and

determining, from the measured voltage, a value of the parameter.

2. The method of claim 1, wherein the parameter is selected from a group consisting of temperature, pressure, volume, velocity, pH, oxygen concentration and humidity.

3. The method of claim 1, further comprising:

measuring a differential mode voltage of the balanced circuit; and

determining, from the differential mode voltage, a value of another distinct parameter of the object or environment.

4. The method of claim 3, wherein the steps of measuring the voltage correlating to the common mode signal and measuring the differential mode voltage are conducted simultaneously.

5. The method of claim 3, wherein the step of measuring the voltage correlating to the common mode signal is performed prior to or subsequent to the step of measuring the differential mode voltage.

6. A method for determining temperature using a resistive sensor having a Wheatstone bridge circuit with at least two variable resistors, wherein the method comprises:

positioning the resistive sensor such that the at least two variable resistors of the Wheatstone bridge circuit are arranged in an environment in which temperature is to be determined;

measuring, while the two variable resistors are arranged in the environment, a temperature detection voltage between;

a first voltage derived from the Wheatstone bridge circuit which is proportional to a summed voltage of signal output nodes of the Wheatstone bridge circuit; and

a second voltage which is proportional to a reference voltage for the Wheatstone bridge circuit; and

determining, from the temperature detection voltage, a temperature of the environment.

7. The method of claim 6, wherein the method of determining the temperature comprises computing the temperature from a polynomial equation having the temperature detection voltage as a variable.

8. The method of claim 6, further comprising:

measuring a differential voltage between the signal output nodes of the Wheatstone bridge circuit; and

determining, from the differential voltage, a pressure of the environment.

9. The method of claim 8, wherein at least one of the steps of measuring the differential voltage and determining the pressure is performed simultaneously with at least one of the steps of measuring the temperature detection voltage and determining the temperature.

10. The method of claim 8, wherein the step of measuring the differential voltage is performed prior to or subsequent to the step of measuring the temperature detection voltage.

11. The method of claim 6, wherein the resistive sensor is disposed within a medical probe.

12. A medical probe, comprising:

a Wheatstone bridge circuit with at least two variable resistors;

compensation circuitry coupled to the Wheatstone bridge circuit which is configured to compensate for variations of a resistive coefficient of a conductive material comprising the Wheatstone bridge circuit due to ambient temperature changes of the conductive material; and

temperature detection circuitry coupled to the Wheatstone bridge circuit which generates a first voltage which is proportional to a summed voltage of signal output nodes of the Wheatstone bridge circuit.

13. The medical probe of claim 12, wherein the compensation circuitry comprises one or more fixed resistors in parallel with at least one of the two variable resistors of the Wheatstone bridge circuit.

14. The medical probe of claim 12, wherein the temperature detection circuitry is disposed within an electrical connector of the medical probe.

15. The medical probe of claim 12, wherein the temperature detection circuitry is disposed within a tip of the medical probe.

16. The medical probe of claim 12, wherein the Wheatstone bridge circuit, the compensation circuitry and the temperature detection circuitry comprise a resistive sensor, and wherein the medical probe is absent a temperature sensor distinct from the resistive sensor.

17. The medical probe of claim 12, further comprising reference voltage circuitry for generating a biased reference voltage relative to an excitation voltage applied to the Wheatstone bridge circuit.

18. The medical probe of claim 12, wherein the medical probe is a catheter.

19. An electronic signal monitoring device for monitoring and processing signals received from a balanced circuit of a medical probe, wherein the electronic signal monitoring device comprises:

a first means for receiving output signals from the balanced circuit;

a second means for determining from one or more of the received output signals a voltage which correlates to a common mode signal of the balanced circuit; and

program instructions which are executable by a processor for determining, from the voltage, a temperature of an environment in which a tip of the medical probe is arranged.

20. The electronic signal monitoring device of claim 19, further comprising a third means for measuring a differential mode voltage of the balanced circuit, wherein the program instructions are further executable by a processor for determining, from the differential voltage, a pressure of the environment.

21. The electronic signal monitoring device of claim 20, wherein the electronic signal monitoring device is configured to utilize the third means and the second means substantially simultaneously.

22. A system, comprising:

a medical probe having a resistive sensor with a Wheatstone bridge circuit including at least two variable resistors;

an electronic signal monitoring device configured for electrical communication with the medical probe to measure electrical parameters of the resistive sensor;

temperature detection circuitry coupled to the Wheatstone bridge circuit that is configured to generate a first voltage which is proportional to a summed voltage of signal output nodes of the Wheatstone bridge circuit, wherein the electronic signal monitoring device comprises a means for measuring a temperature detection voltage between the first voltage and a second voltage which is proportional to a reference voltage for the Wheatstone bridge circuit; and

a storage medium comprising program instructions which are executable by a processor for determining, from the temperature detection voltage, a temperature of an environment in which a tip of the medical probe is arranged.

23. The system of claim 22, wherein the temperature detection circuitry is configured for coupling between the medical probe and the electronic signal monitoring device.

24. The system of claim 22, wherein the temperature detection circuitry is disposed within the medical probe.

25. The system of claim 22, wherein the temperature detection circuitry is disposed within the electronic signal monitoring device.

26. The system of claim 22, wherein the electronic signal monitoring device comprises another means for measuring a differential voltage between the signal output nodes of the Wheatstone bridge circuit, and wherein the program instructions are further executable by a processor for determining, from the differential voltage, a pressure of the environment.