Fluid temperature and flow sensor apparatus and system for cardiovascular and other medical applications

Abstract

Apparatus ( 100 ) is provided comprising an optical micro-sensor ( 10 ) for directly measuring a fluid temperature and flow by thermoconvection, which suitable for medical applications, e.g. using minimally-invasive cardiovascular techniques. A multi-sensor apparatus ( 100 ) may take the form of a micro-catheter or steerable guidewire, equipped with a plurality of miniaturized optical sensors ( 10 ) arranged along a length of the distal end ( 101 ), each coupled via optical fibers ( 11 ) to a proximal end ( 102 ) comprising an input/output connector ( 112 ) to the control system ( 110 ), without the need for electrical connections. This enables direct measurement of blood flow, temperature and/or blood pressure simultaneously at several locations within the blood vessels or the heart, including transvalvular measurements. Preferably, the distal end portion has a diameter of 0.89 mm (0.035″) or less, and more preferably 0.46 mm (0.018″) or less, so that there is negligible effect on valve movement, transvalvular pressure gradient and flow during measurement.

1 . Sensor apparatus for measuring a fluid temperature and flow by a thermoconvection effect, comprising:
 optical flow sensor means, integrated within a microcatheter or a guidewire, comprising an optical fiber coupled at a distal end to a Micro-Opto-Mechanical-System (MOMS) sensor element capable of being optically heated and having a temperature dependent optical characteristic, and optical input/output means at a proximal end of the optical fiber for optically coupling the sensor element to a control means for detecting said optical characteristic indicative of temperature, for optically heating the sensor element, and for detecting a change in temperature of the MOMs sensor element indicative of fluid flow.   
     
     
         2 . Sensor apparatus according to  claim 1  comprising an assembly of a plurality of MOMs sensor elements and a plurality of optical fibers integrated within the microcatheter or guidewire, each MOMS sensor element coupled by a respective individual optical fiber to the optical input/output means. 
     
     
         3 . Sensor apparatus according to  claim 1  wherein the MOMS sensor element comprises a Fabry-Pérot MOMS sensor having a temperature dependent cavity length. 
     
     
         4 . Sensor apparatus according to  claim 1 , wherein the control means comprises an optical source and detection means for detecting the temperature dependent optical characteristic of the MOMS sensor element, an optical heating means for heating the MOMS sensor element, and processing means comprising hardware and/or software for processing optical data indicative of temperature and flow values to derive therefrom fluid temperature and fluid flow measurements. 
     
     
         5 . An apparatus for measuring a cardiovascular temperature and flow by thermoconvection comprising:
 a sensor assembly integrated within a micro-catheter or a guidewire comprising a distal end portion and a distal tip having a diameter suitable for introduction intravascularly or intraluminally through small vessels; and   the sensor assembly comprising optical sensor means within the distal end portion comprising at least one optical sensor element having a temperature dependent optical characteristic and capable of being optically heated for measurement of flow by thermoconvection, an aperture in the micro-catheter or guidewire adjacent each sensor element for fluid contact, and each sensor element being optically coupled by a respective individual optical fiber to optical input/output means at a proximal end of the sensor assembly for connection to a control system for detecting said optical characteristic indicative of temperature, for heating the sensor element and optically detecting a change in temperature of the sensor element indicative of a flow.   
     
     
         6 . An apparatus according to  claim 5 , wherein distal end portion has an outside diameter of 0.89 mm (0.035″) or less. 
     
     
         7 . An apparatus according to  claim 5 , wherein the distal end portion has an outside diameter of 0.46 mm (0.018″) or less. 
     
     
         8 . (canceled) 
     
     
         9 . (canceled) 
     
     
         10 . An apparatus according to  claim 5  wherein each sensor element comprises a semiconductor material having a temperature dependent bandgap, and wherein the semiconductor material comprises one of: a bulk direct-bandgap material, a multilayer semiconductor structure and a multiquantum well structure. 
     
     
         11 . (canceled) 
     
     
         12 . An apparatus according to  claim 5  wherein each sensor element comprises a MOMS sensor. 
     
     
         13 . An apparatus according to  claim 12  wherein the MOMS sensors comprise Fabry-Pérot MOMS sensors having a temperature dependent cavity length. 
     
     
         14 . An apparatus according to  claim 5 , wherein a plurality of said sensor elements are provided along a length of 4 cm to 7 cm of the distal end portion. 
     
     
         15 . (canceled) 
     
     
         16 . (canceled) 
     
     
         17 . (canceled) 
     
     
         18 . An apparatus according to  claim 5  wherein the sensor assembly is integrated within a guidewire further comprising torque steering components for guiding the sensor assembly. 
     
     
         19 . An apparatus according to  claim 18  wherein the torque steering components comprise a mandrel extending axially along the length of the sensor assembly and an outer layer comprising a coil of the guidewire having an external diameter along the length of the distal end portion of 0.89 mm (0.035″) or less, and preferably has a diameter of 0.46 mm (0.018″) or less. 
     
     
         20 . An apparatus according to  claim 19  wherein wherein the distal tip comprises a J-tip. 
     
     
         21 . (canceled) 
     
     
         22 . An apparatus according to  claim 5  wherein the optical input/output means comprises a connector for removably coupling the sensor assembly and the control system. 
     
     
         23 . (canceled) 
     
     
         24 . (canceled) 
     
     
         25 . An apparatus according to  claim 22  wherein the connector provides for an electrical connection for electrically heating the sensor element. 
     
     
         26 . An apparatus according to  claim 22  wherein the control system comprises:
 an optical controller for optically heating each sensor element and for measuring a change in the optical characteristic indicative of a temperature change. 
 
     
     
         27 . A control system for the apparatus of  claim 5 , wherein the control system comprises a heating means, and a light source and detection means for coupling to each of the optical sensors for measuring the optical characteristic. 
     
     
         28 . A control system according to  claim 27  wherein the heating means comprises an optical heating means. 
     
     
         29 . A control system according to  claim 27  further comprising processing means comprising hardware and/or software for processing optical data indicative of temperature and flow values to derive therefrom temperature and flow measurements. 
     
     
         30 . (canceled) 
     
     
         31 . (canceled)