System For Sensing a Mechanical Property of a Sample

Abstract

A sensing element for sensing a mechanical property of a sample defining a sample surface using a contact force exerted the sample surface. The sensing element includes: a deformable element defining a contact surface and a deformable section in register with the contact surface, the deformable section being deformable between an undeformed configuration and a deformed configuration; a deformation sensor operatively coupled to the deformable section for sensing and quantifying a deformation of the deformable section between the deformed and undeformed configurations, the deformation sensor being an optical deformation sensor; and a force sensor operatively coupled to the deformable element for sensing the contact force exerted on the contact surface.

1 . A sensing element for sensing a mechanical property of a sample defining a sample surface using a contact force exerted on said sensing element by said sample surface, said sensing element comprising:
 a deformable element defining a deformable element first end and a substantially opposed deformable element second end, said deformable element defining a contact surface and a deformable section substantially in register with said contact surface between said deformable element first and second ends, said deformable section being deformable between an undeformed configuration and a deformed configuration, wherein said deformable section is in said undeformed configuration when no external forces are exerted on said contact surface and said deformable section is in said deformed configuration when said contact force is exerted on said contact surface;   a deformation sensor operatively coupled to said deformable section for sensing and quantifying a deformation of said deformable section between said deformed and undeformed configurations, said deformation sensor being an optical deformation sensor; and   a force sensor operatively coupled to said deformable element for sensing said contact force exerted on said contact surface;   whereby, when said contact and sample surfaces are abutted against each other and biased toward each other
 said contact force is created on said contact surface and sensed by said force sensor; and 
 said deformable section achieves said deformed configuration, said deformed configuration being sensed and quantified by said deformation sensor. 
   
     
     
         2 . A sensing element as defined in  claim 1 , wherein said deformation sensor includes a deformation sensor interrupted optical waveguide defining a deformation sensor waveguide first segment, a deformation sensor waveguide second segment and a deformation sensor gap extending therebetween, said deformation sensor gap being provided substantially in register with said deformable section, said deformation sensor waveguide first and second segments being optically coupled to each other across said deformation sensor gap and secured to said deformable element with said deformation sensor waveguide first and second segments fixed with respect to said deformable section substantially adjacent said deformation sensor gap, whereby optical coupling between said deformation sensor waveguide first and second segments varies as said deformable section is moved between said undeformed and deformed configurations. 
     
     
         3 . A sensing element as defined in  claim 2 , wherein said deformable element defines a waveguide receiving surface opposed to said contact surface, said deformation sensor interrupted optical waveguide being secured to said waveguide receiving surface. 
     
     
         4 . A sensing element as defined in  claim 3 , wherein said deformation sensor interrupted optical waveguide is a deformation sensor optical fiber, said deformation sensor waveguide first and second segments being respectively a deformation sensor fiber first segment and a deformation sensor fiber second segment. 
     
     
         5 . A sensing element as defined in  claim 4 , wherein said waveguide receiving surface defines a substantially elongated fiber receiving groove extending thereinto, said deformation sensor fiber first and second segments being provided in said fiber receiving groove. 
     
     
         6 . A sensing element as defined in  claim 5 , wherein said deformation sensor waveguide first and second segments are bonded to said deformable element in said fiber receiving groove. 
     
     
         7 . A sensing element as defined in  claim 2 , wherein
 said deformation sensor waveguide first segment extends between said deformable element first end and said deformation sensor gap; and   said deformation sensor waveguide second segment extends between said deformable element second end and said deformation sensor gap.   
     
     
         8 . A sensing element as defined in  claim 2 , wherein said deformation sensor waveguide first segment extends between said deformable element first end and said deformation sensor gap, and said deformation sensor waveguide second segment extends from said deformation sensor gap towards said deformable element second end and is provided with a light reflective end surface opposed to said deformation sensor gap. 
     
     
         9 . A sensing element as defined in  claim 2 , wherein
 said deformable element defines an auxiliary light guiding element provided between said deformation sensor gap and said deformable element second end;   said deformation sensor waveguide first segment extends between said deformable element first end and said deformation sensor gap;   said deformation sensor waveguide second segment extends between said deformation sensor gap and said auxiliary light guiding element;   said deformation sensor interrupted optical waveguide defines a deformation sensor waveguide third segment extending between said deformable element first end and said auxiliary light guiding element;   said auxiliary light guiding element optically couples said deformation sensor waveguide second and third segments.   
     
     
         10 . A sensing element as defined in  claim 9 , wherein said auxiliary light guiding element includes a mirror. 
     
     
         11 . A sensing element as defined in  claim 9 , wherein said auxiliary light guiding element includes a pair of mirrors configured for changing a light direction propagation of light incoming at said mirrors by about 180 degrees. 
     
     
         12 . A sensing element as defined in  claim 9 , wherein said deformation sensor waveguide second and third segments are in a substantially parallel and spaced apart relationship relative to each other. 
     
     
         13 . A sensing element as defined in  claim 2 , further comprising a base, said base and said deformable element extending in a substantially parallel and spaced apart relationship relative to each other. 
     
     
         14 . A sensing element as defined in  claim 13 , further comprising a first spacing element extending between said base and said deformable element substantially adjacent said deformable element first end. 
     
     
         15 . A sensing element as defined in  claim 14 , wherein said deformable element second end is movable with respect to said base. 
     
     
         16 . A sensing element as defined in  claim 14 , further comprising a second spacing element extending between said base and said deformable element substantially adjacent said deformable element second end. 
     
     
         17 . A sensing element as defined in  claim 2 , wherein in said undeformed configuration, said deformation sensor waveguide first and second segments have substantially coaxial optical axes. 
     
     
         18 . A sensing element as defined in  claim 1 , wherein said deformation sensor includes at least two deformation sensor interrupted optical waveguides each defining a respective deformation sensor waveguide first segment, a respective deformation sensor waveguide second segment and a respective deformation sensor gap extending therebetween, said deformation sensor gaps being provided substantially in register with said deformable section, said respective deformation sensor waveguide first and second segments being optically coupled to each other across said respective deformation sensor gaps and each secured to said deformable element with said deformation sensor waveguide first and second segments fixed with respect to said deformable section substantially adjacent said deformation sensor gaps, whereby optical coupling between said deformation sensor waveguide first and second segments varies as said deformable section is moved between said undeformed and deformed configurations. 
     
     
         19 . A sensing element as defined in  claim 18 , wherein said deformation sensor interrupted optical waveguides extend substantially parallel to each other in a laterally spaced apart relationship relatively to each other. 
     
     
         20 . A sensing element as defined in  claim 18 , wherein said deformation sensor gaps are longitudinally offset with respect to each other. 
     
     
         21 . A sensing element as defined in  claim 1 , further comprising
 a base, said base and said deformable element extending in a spaced apart relationship relative to each other; and   a first spacing element extending between said base and said deformable element.   
     
     
         22 . A sensing element as defined in  claim 21 , wherein said base and said deformable element extend in a substantially parallel relationship relative to each other. 
     
     
         23 . A sensing element as defined in  claim 21 , wherein said force sensor is an optical force sensor. 
     
     
         24 . A sensing element as defined in  claim 21 , wherein said force sensor includes a force sensor interrupted optical waveguide defining a force sensor waveguide first segment, a force sensor waveguide second segment and a force sensor gap extending therebetween, said force sensor waveguide first segment extending through said first spacing element and being fixed relative thereto substantially adjacent said force sensor gap, said force sensor waveguide second segment being supported by said base and fixed relative thereto substantially adjacent said force sensor gap, said force sensor waveguide first and second segments being optically coupled to each other across said force sensor gap, said first spacing element including a first support resiliently deformable section provided between said base and said force sensor optical waveguide first segment, whereby, when said first support resiliently deformable section is compressed, said force sensor waveguide first segment is moved relative to said force sensor waveguide second segment, which changes optical coupling between said force sensor waveguide first and second segments. 
     
     
         25 . A sensing element as defined in  claim 24 , wherein said force sensor interrupted optical waveguide is a force sensor optical fiber, said force sensor waveguide first and second segments being respectively a force sensor fiber first segment and a force sensor fiber second segment. 
     
     
         26 . A sensing element as defined in  claim 25 , wherein said force sensor fiber first and second segments are inserted respectively through a first ferrule and a second ferrule, said first ferrule extending through said first spacing element and said second ferrule being supported by said base. 
     
     
         27 . A sensing element as defined in  claim 24 , wherein said first support resiliently deformable section is made out of a material selected from the group consisting of Polydimethylsiloxane (PDMS), silicone rubbers, epoxy, and rubbers. 
     
     
         28 . A sensing element as defined in  claim 21 , wherein said first spacing element is substantially adjacent said deformable element first end. 
     
     
         29 . A sensing element as defined in  claim 21 , further comprising a second spacing element extending between said base and said deformable element, said first and second spacing elements being spaced apart from each other and respectively provided substantially adjacent said deformable element first and second ends. 
     
     
         30 . A sensing element as defined in  claim 29 , wherein said force sensor includes
 a force sensor first interrupted optical waveguide defining a force sensor first waveguide first segment, a force sensor first waveguide second segment and a force sensor first gap extending therebetween, said force sensor first waveguide first segment extending through said first spacing element and being fixed relative thereto substantially adjacent said force sensor first gap, said force sensor first waveguide second segment being supported by said base and fixed relative thereto substantially adjacent said force sensor first gap, said force sensor first waveguide first and second segments being optically coupled to each other across said force sensor first gap, said first spacing element including a first support resiliently deformable section provided between said base and said force sensor first waveguide first segment;   a force sensor second interrupted optical waveguide defining a force sensor second waveguide first segment, a force sensor second waveguide second segment and a force sensor second gap extending therebetween, said force sensor second waveguide first segment extending through said second spacing element and being fixed relative thereto substantially adjacent said force sensor second gap, said force sensor second waveguide second segment being supported by said base and fixed relative thereto substantially adjacent said force sensor second gap, said force sensor second waveguide first and second segments being optically coupled to each other across said force sensor second gap, said second spacing element including a second support resiliently deformable section provided between said base and said force sensor second waveguide first segment;   whereby, when said first support resiliently deformable section is compressed, said force sensor first waveguide first segment is moved relative to said force sensor first waveguide second segment, which changes optical coupling between said force sensor first waveguide first and second segments, and when said second support resiliently deformable section is compressed, said force sensor second waveguide first segment is moved relative to said force sensor second waveguide second segment, which changes optical coupling between said force sensor second waveguide first and second segments.   
     
     
         31 . A sensing element as defined in  claim 21 , wherein said force sensor includes a piezoresistive or a piezoelectric element provided between said first spacing element and said base. 
     
     
         32 . A system for measuring a mechanical property of a sample defining a sample surface using a contact force by said sample surface, said system comprising:
 a sensing element as defined in  claim 2 ;   a light source optically coupled to said deformation sensor waveguide first segment opposed to said deformation sensor gap for emitting a source light in said deformation sensor waveguide first segment;   a light detector optically coupled to said deformation sensor waveguide second segment opposed to said deformation sensor gap for detecting an intensity of light received from said deformation sensor waveguide second segment;   a controller operatively coupled to said light detector for receiving said intensity of light received from said deformation sensor waveguide second segment when said source light is emitted in said deformation sensor waveguide first segment and computing a deformation of said deformable section using a power loss of said source light across said sensing element; and   an output element for outputting said deformation.   
     
     
         33 . A system for measuring a mechanical property of a sample defining a sample surface using a contact force exerted on said sensing element by said sample surface, said system comprising:
 a sensing element as defined in  claim 2 ;   a light source optically coupled to said force sensor waveguide first segment opposed to said force sensor gap for emitting a source light in said force sensor waveguide first segment;   a light detector optically coupled to said force sensor waveguide second segment opposed to said force sensor gap for detecting an intensity of light received from said force sensor waveguide second segment;   a controller operatively coupled to said light detector for receiving said intensity of light received from said force sensor waveguide second segment when said source light is emitted in said force sensor waveguide first segment and computing said contact force exerted on said contact surface using a power loss of said source light across said sensing element; and   an output element for outputting said contact force.   
     
     
         34 . (canceled) 
     
     
         35 . (canceled)