Combined flow, pressure and temperature sensor
First Claim
1. A device for determining pressure, temperature and a flow parameter of a flowing fluid, comprisingi) a sensor support body (13) mounted for insertion into a vessel of a living body and having a diaphragm (15) covering a cavity (14) formed in said support body (13);
- ii) a pressure sensitive element (41), having a known temperature dependence, mounted on said diaphragm (15), and providing an output indicative of a pressure;
iii) a temperature sensitive resistor (42) mounted in the vicinity of said pressure sensitive element (41) and having a known temperature dependence, providing an output signal indicative of a temperature, said resistor (42) also functioning as a temperature reference means for said pressure sensitive element (41); and
iv) an electrical circuit (43, 44, 45, 46), connected to the pressure sensitive element and to the temperature sensitive resistor, for calculation of a flow parameter of said flowing fluid on the basis of the temperature signals.
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Accused Products
Abstract
The invention relates to a device for measuring pressure, temperature and/or flow velocity. It includes a sensor (6) with a sensor support body (13) provided with a diaphragm (15) covering a cavity (14) formed in the support body (13). A pressure sensitive element (41) is mounted on the diaphragm, for recording pressure. Furthermore, a temperature sensitive resistor (42) is mounted in the vicinity of the pressure sensitive resistor and has a known temperature dependence, for recording temperature. It also includes an electrical circuit (43, 44, 45, 46) selectively outputting signals from either of the pressure sensitive element and the temperature sensitive resistor.
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Citations
36 Claims
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1. A device for determining pressure, temperature and a flow parameter of a flowing fluid, comprising
i) a sensor support body (13) mounted for insertion into a vessel of a living body and having a diaphragm (15) covering a cavity (14) formed in said support body (13); -
ii) a pressure sensitive element (41), having a known temperature dependence, mounted on said diaphragm (15), and providing an output indicative of a pressure;
iii) a temperature sensitive resistor (42) mounted in the vicinity of said pressure sensitive element (41) and having a known temperature dependence, providing an output signal indicative of a temperature, said resistor (42) also functioning as a temperature reference means for said pressure sensitive element (41); and
iv) an electrical circuit (43, 44, 45, 46), connected to the pressure sensitive element and to the temperature sensitive resistor, for calculation of a flow parameter of said flowing fluid on the basis of the temperature signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A guide wire and sensor assembly for determining pressure, temperature and a flow parameter of a fluid flowing in a living body, comprising
i) a guide wire (2) having a distal and a proximal end; -
ii) a sensor element (6) provided at the distal end of said guide wire, said sensor element comprising a) a sensor support body (13) provided with a diaphragm (15) covering a cavity (14) formed in said support body;
b) a pressure sensitive element (41) having a known temperature dependence and mounted on said diaphragm (15), recording pressure; and
c) a temperature sensitive resistor (42) mounted in the vicinity of said pressure sensitive element (41) and having a known temperature dependence, recording temperature, said resistor (42) also functioning as a temperature reference for the pressure sensitive element (41) and to provide temperature signals for calculation of a flow parameter; and
iii) an electrical circuit comprising a double Wheatstone bridge, including a first (42, 43, 44, 46) and a second (41, 42, 45, 46) bridge, said two bridges together comprising six resistive elements, said double Wheatstone bridge having two resistors in common, whereby the second bridge includes said pressure sensitive element (41) and said temperature sensitive resistor (42), and the first bridge includes the temperature sensitive resistor (42).
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14. A guide wire and sensor assembly for determining pressure, temperature and a flow parameter of a fluid flowing in a vessel, comprising
i) a guide wire (2) having a distal and a proximal end; -
ii) a sensor element (6) provided at the distal end of said guide wire, said sensor element comprising a) a sensor support body (13) provided with a diaphragm (15) covering a cavity formed in said support body (13);
b) a pressure sensitive element (41) having a known temperature dependence and mounted on said diaphragm (15), recording pressure; and
c) a temperature sensitive resistor (42) mounted in the vicinity of said pressure sensitive element and having a known temperature dependence, recording temperature, said resistor also functioning as a temperature reference for the pressure sensitive element and to provide temperature signals for calculation of a flow parameter; and
iii) an electrical circuit selectively recording output signals from either of said pressure sensitive element and said resistor, said circuit comprising a Wheatstone bridge (51, 52, 53, 54), wherein the output from the bridge is indicative of pressure, and the total impedance of the bridge is indicative of temperature. - View Dependent Claims (15, 16, 17, 18)
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19. A method of determining pressure, temperature and a flow parameter of fluid flowing in vessels, comprising the following steps:
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a) providing a pressure sensitive element and a resistor on a sensor element at a measurement site in a vessel of a living body, said pressure sensitive element and said resistor being part of an electric circuit yielding a pressure indicative output and a temperature indicative output, said pressure sensitive element and said resistor having known temperature dependencies, whereby the resistor is used as a reference for the pressure sensitive element;
b) subjecting said sensor element to flowing fluid and monitoring the pressure and temperature of said fluid by continuously recording said pressure indicative output and said temperature indicative output from said electric circuit;
c) subjecting said resistor to a changed thermal environment;
d) registering the change in said temperature indicative output resulting from said changed thermal environment; and
e) calculating a flow parameter from said change in said temperature indicative output. - View Dependent Claims (20, 21, 22, 23)
wherein V is the volume of injected liquid Tm is the measured temperature Tl is the temperature of injected liquid To is the temperature of the blood, i.e. 37°
C.Q is the volume flow to is the point in time where a temperature change is detected t1 is the point in time where the temperature is regarded as having reached normal temperature.
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22. The method of claim 19, wherein said changed thermal environment is achieved by said resistor being heated by passing a current through it, whereby said fluid cools said resistor such that the actual temperature of said resistor is lower than the expected temperature, that would have been obtained, had said resistor not been subjected to said flowing fluid, and calculating a flow parameter from said deviation from said expected temperature value, said flow parameter being a quantity proportional to the flow velocity.
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23. The method of claim 22, wherein a flow velocity is calculated using the equation
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24. A method of diagnosing small vessel disease, comprising performing a measurement at a site in a vessel distally of a suspected stricture according to the following steps:
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a) providing a pressure sensitive element and a resistor on a sensor element at a measurement site, said pressure sensitive element and said resistor being part of an electric circuit yielding a pressure indicative output and a temperature indicative output, said pressure sensitive element and said resistor having known temperature dependencies, whereby the resistor is used as a reference for the pressure sensitive element;
b) subjecting said sensor element to flowing fluid and monitoring the pressure and temperature of said fluid by continuously recording said pressure indicative output and said temperature indicative output from said electric circuit;
c) subjecting said resistor to a changed thermal environment;
d) registering the change in said temperature indicative output resulting from said changed thermal environment; and
e) calculating a flow parameter from said change in said temperature indicative output; and
f) comparing the calculated flow parameter and the measured pressure with corresponding quantities representative of a healthy patient. - View Dependent Claims (25)
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26. A method of diagnosing small vessel disease, comprising performing measurements at a site in a vessel distally of a suspected stricture according to the following steps:
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a) providing a pressure sensitive element and a resistor on a sensor element at a measurement site, said pressure sensitive element and said resistor being part of an electric circuit yielding a pressure indicative output and a temperature indicative output, said pressure sensitive element and said resistor having known temperature dependencies, whereby the resistor is used as a reference for the pressure sensitive element;
b) subjecting said sensor element to flowing fluid and monitoring the temperature of said fluid by continuously recording said temperature indicative output from said electric circuit;
c) subjecting said resistor to a changed thermal environment;
d) registering the change in said temperature indicative output resulting from said changed thermal environment;
e) calculating a flow parameter (Qrest) from said change in said temperature indicative output;
f) injecting a vaso dilating drug in said vessel to simulate a work condition;
g) monitoring the pressure (Pwork,dist) and temperature of said fluid by continuously recording said pressure indicative output and said temperature indicative output from said electric circuit;
h) subjecting said resistor to a changed thermal environment;
i) registering the change in said temperature indicative output resulting from said changed thermal environment;
j) calculating a flow parameter (Qwork) from said change in said temperature indicative output;
k) determining the proximal pressure (Pprox,work);
l) calculating
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27. A device for biological pressure and temperature measurements, comprising:
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a guide wire;
a pressure sensor mounted on the guide wire;
a temperature sensor mounted on the guide wire in the vicinity of the pressure sensor; and
an electronic circuit to generate and output an indication of temperature based on signals from the temperature sensor. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35, 36)
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Specification