Optical Pressure Measurement

Abstract

Sensing apparatus, consisting of a housing, including a medium having an elastic, transparent outer surface configured to contact a tissue within a living body and to deform in response to a force exerted by the body tissue on the surface. The apparatus has a radiation source contained in the housing and configured to direct radiation toward the surface, as well as a radiation detector contained in the housing and configured to sense the radiation that is reflected from the surface and to output a signal indicative of an amplitude of the reflected radiation. The apparatus further has a processor, which is coupled to measure a change in the signal due to deformation of the surface and, responsively to the change, to output an indication of the force.

We claim: 
     
         1 . An optical pressure sensing apparatus comprising:
 a cylindrically shaped transparent solid medium attached to a housing, the solid medium having a proximal end, a distal end, an axis of symmetry and an elastic distal transparent outer surface configured to contact a tissue within a living body and to deform in response to a force exerted by the body tissue on the distal outer surface;   a radiation source contained in the housing and coupled to a proximal surface of the transparent solid medium to direct radiation through the transparent solid medium toward the distal outer surface, the proximal surface being opposite the distal outer surface; and   a radiation detector contained in the housing and mounted to the proximal surface of the transparent solid medium.   
     
     
         2 . The apparatus according to  claim 1 , wherein the radiation source is fixedly mounted on a further outer surface of the medium opposite the elastic outer surface. 
     
     
         3 . The apparatus according to  claim 1 , wherein the radiation source is coupled to a further outer surface of the medium opposite the elastic outer surface with a radiation guide. 
     
     
         4 . The apparatus according to  claim 1 , wherein the radiation detection is fixedly mounted on a further outer surface of the medium opposite the elastic outer surface. 
     
     
         5 . The apparatus according to  claim 1 , wherein the radiation detector is coupled to a further outer surface of the medium opposite the elastic outer surface with a radiation guide. 
     
     
         6 . The apparatus according to  claim 1 , wherein the housing comprises an external wall of a catheter probe. 
     
     
         7 . Apparatus to sense force, comprising:
 an elastic transparent solid medium having a proximal end and distal end with an axis of symmetry, the solid medium includes a first outer surface on the distal end configured to contact a tissue within a living body and to deform in response to a force exerted by the tissue on the first outer surface;   a radiation source mounted directly to a second outer surface of the medium, the second outer surface being opposite the first outer surface in a direction along the axis of symmetry, the radiation source configured to direct radiation toward the first outer surface; and   a radiation detector mounted directly to the second outer surface of the medium.   
     
     
         8 . The apparatus according to  claim 7 , wherein the radiation source is fixedly mounted to the second outer surface. 
     
     
         9 . The apparatus according to  claim 7 , wherein the radiation source is connected to the second outer surface with a radiation guide. 
     
     
         10 . The apparatus according to  claim 7 , wherein the radiation detector is connected to the second outer surface with a radiation guide.