Fiber Optic Probes

• US 20020041724A1
• Filed: 09/07/2001
• Published: 04/11/2002
• Est. Priority Date: 09/07/2000
• Status: Active Grant

• Current Assignee: Medxense AS
• Original Assignee: Invivosense ASA
• Inventors: Ronnekleiv, Erlend, Berg, Arne, Ellingsen, Reinold, Kringlebotn, Jon Thomas, Hjeime, Dag Roar
• Granted Patent: US 7,003,184 B2
• Time in Patent Office: Days
• US Class Current: 385/12
• CPC Class Codes: A61B 2562/0266 Optical strain gauges
• CPC Class Codes: A61B 5/01 Measuring temperature of body parts ; Diagnostic temperature sensing, e.g. for malignant or inflamed tissue clinical contact thermometers G01K13/20
• CPC Class Codes: A61B 5/02154 by optical transmission
• CPC Class Codes: A61B 5/036 by means introduced into body tracts A61B5/032 and A61B5/035 take precedence
• CPC Class Codes: G01N 2021/7723 Swelling part, also for adsorption sensor, i.e. without chemical reaction
• CPC Class Codes: G01N 21/45 using interferometric methods; using Schlieren methods
• CPC Class Codes: G01N 21/774 the reagent being on a grating or periodic structure
• CPC Class Codes: G02B 6/022 using mechanical stress, e.g. tuning by compression or elongation, special geometrical shapes such as "dog-bone" or taper G02B6/02204 takes precedence; optical modulation using photo-elastic effect G02F1/0131
• CPC Class Codes: G02B 6/241 Light guide terminations

Abstract

A body compatible fiber optic sensor probe for invasive medical use is provided. The probe includes at least one sensing location at which the fiber is configured to provide at least one detectable changeable optical property responsive to strain within the fiber, and at least one sensing element which undergoes a volumetric change in response to an in body parameter to be sensed. The sensing element is coupled to the fiber in such a way that the volumetric change induces strain within the fiber so as to vary the detectable optical property or properties.

Claims

1. A body compatible fiber optic sensor probe for invasive medical use, the probe including:

a fiber;

a sensing location at which the fiber is configured to provide at least one detectable changeable optical property responsive to a strain within the fiber;

at least one sensing element which undergoes a volumetric change in response to an in body parameter to be sensed;

wherein the sensing element is coupled to the fiber in such a way that the volumetric change induces the strain within the fiber so as to vary the detectable changeable optical property.

2. A probe as claimed in claim 1 wherein the at least one sensing element comprises a mass of reactive material.

3. A probe as claimed in claim 1 wherein the sensing element creates a radial and/or a longitudinal strain within the fiber in such a way as to change an optical response of the fiber.

4. A probe as claimed in claim 1 wherein said fiber comprises a fiber core having one or more fiber Bragg gratings (FBG'"'"'s) written the fiber core.

5. A probe as claimed in claim 4 wherein the length of an FBG is between 1 and 70 mm.

6. A probe as claimed in claim 1 comprising an active fiber laser including said fiber.

7. A probe as claimed in claim 1 which comprises at least one sensing location including an active FBG laser or a passive FBG device providing a birefringent optical output or response dependent upon at least one parameter to be measured.

8. A probe as claimed in claim 1 wherein comprising a plurality of sensing locations spaced apart at a distance between 1 and 100 mm.

9. A probe as claimed in claim 1 wherein said fiber has a fibre cladding and comprising at least one sensing location provided with a sensing element in the form of a reactive coating which is disposed directly or indirectly on the fiber cladding, and wherein the coating is configured to create a strain within the fiber responsive to at least one body parameter to be measured, the strain providing a change in at least one detectable optical property of the fiber.

10. A probe as claimed in claim 9 wherein the coating is formed from one or more of a plurality of different materials, each material responsive to a selected physical or chemical parameter within the body.

11. A probe as claimed in claim 10 wherein said parameters are selected from the group comprising temperature, pressure, radiation including non-ionizing radiation and ionizing radiation, a particular chemical or biological substance, and chemical or biological, including immunological, interactions.

12. A probe as claimed in claim 9 wherein the reactive coating is formed of a body compatible material such that the coating is able in use directly to contact a biological material within the body.

13. A probe as claimed in claim 9 further comprising a protective membrane arranged over the reactive coating, said membrane allowing measurement of a particular parameter but providing in use a barrier between said coating and a body material.

14. A probe as claimed in claim 13 wherein the membrane is arranged to allow selected target molecules to diffuse from the body side through to the coating material forming the sensing element.

15. A probe as claimed in claim 9 wherein the fiber has a fiber axis and the reactive coating is provided at a number of different regions spaced along the fiber axis.

16. A probe as claimed in claim 1 wherein the sensing element is coupled to the fiber at two or more axially spaced locations.

17. A probe as claimed in claim 16 wherein the sensing element comprises a cylinder fitted over the optical fiber and secured thereto at axially spaced locations.

18. A probe as claimed in claim 16 wherein the cylinder comprises a first end and a second end and wherein said first end engages a flange extending outwardly from the fiber, and said second end of the cylinder is suitably bonded to the fiber.

19. A probe as claimed in claim 1 wherein the sensing element is arranged to engage a piston carried by or coupled to the fiber.

20. A probe as claimed in claim 1 wherein the sensing element is contained within a cylinder.

21. A probe as claimed in claim 20 wherein the sensing element is a solid or semi-solid material located within the cylinder.

22. A probe as claimed in claim 20 wherein the sensing element is a flowable liquid or gel which expands within the cylinder.

23. A probe as claimed in claim 20 wherein the measurand to be sensed is temperature and the cylinder is formed of a material having a good thermal conductivity.

24. A probe as claimed in claim 20 wherein the probe is a sensor for chemical or biological material, and the cylinder is formed of a material provided with means to enable the molecules of the chemical or biological material to be sensed to permeate through the cylinder walls.

25. A probe as claimed in claim 20 wherein the piston/cylinder arrangement is acted on by first and second sensing elements arranged to apply force to the fiber in opposite directions, the first and second sensing elements each providing a similar response in relation to a first set of parameters, but a different response in relation to a selected measurand.

26. A probe as claimed in claim 1 wherein a rigid or semi-rigid housing or a sleeve is provided around the fiber at the sensing location or locations thereof, wherein a or the sensing element is provided in an annular cavity defined between the housing or sleeve and the fiber.

27. A probe as claimed in claim 26 wherein the measurand to be sensed is temperature and the sleeve or housing is formed of a material with good thermal conductivity.

28. A probe as claimed in claim 26 wherein the sensor is a chemical or biochemical sensor, and wherein the sleeve or housing is configured to allow the ingress of a target measurand.

29. A probe as claimed in claim 1 wherein the sensing element applies a sideways force on a sensing region of the fibre to establish a bending strain therein.

30. A probe as claimed in claim 29 comprising first and second sensing elements mounted within a housing, said first sensing element being arranged to urge a free end of the fibre in a first direction and said second sensing element being arranged to urge the free end of the fibre in a second direction, said second direction being opposite to the first direction.

31. A probe as claimed in claim 30 wherein said first sensing element is reactive to a particular chemical or biological substance, and the second sensing element is insensitive to said particular chemical or biological substance but is otherwise of similar construction to the first sensing element.

32. A probe as claimed in claim 1 wherein the optical fiber is birefringent.

33. A probe as claimed in claim 32 wherein the fiber comprises one or more side holes at the sensing location.

34. A probe as claimed in claim 33 wherein a or the sensing element is provided in said side hole.

35. A probe as claimed in claim 34 wherein the fibre is provided with a membrane at a free end thereof allowing a chemical or biological substance to diffuse through the membrane so as to contact the sensing element material within the side-hole.

36. A probe as claimed in claim 1 wherein said sensing element comprises a reactive material immobilized on a solid support medium.

37. A probe as claimed in claim 36 wherein the reactive material is mechanically, electrostatically or chemically immobilized.

38. A probe as claimed in claim 36 wherein the solid support medium is a polymer, copolymer, or a glass.

39. A probe as claimed in claim 36 wherein the support medium is inert to the reaction being analysed.

40. A probe as claimed in claim 36 wherein the support itself acts as a selective element.

41. A probe as claimed in claim 40 wherein the solid support is selective through controlled porosity.

42. A probe as claimed in claim 1 wherein the sensing element comprises a reactive material dispersed or immobilized in a fluid or gel, wherein the fluid or gel swells or contracts in response to a target measurand.

43. A probe as claimed in claim 1 wherein a separate body compatible membrane is provided covering or enclosing the sensing element.

44. A probe as claimed in claim 43 wherein the membrane is selective of the measurand species based on one of size selectivity through controlled porosity of the membrane;

chemical/biochemical selectivity through chemical reactions;

or ionic selectivity through electrostatic interactions.

45. A probe as claimed in claim 1 wherein the sensing element comprises a coating of paint or bonding material such as a polymer gel network.

46. A probe as claimed in any of claims 1 wherein the sensing element comprises a coating of a porous material such as sol-gel glass or ceramics.

47. A probe as claimed in claim 1 wherein the sensing element comprises micro-spherical balls, provided with additives generating chemical selectivity for a selected group of molecules.

48. A probe as claimed in claim 1 wherein the sensing element comprises ionic N-Isopropylacrylamide (NIPA) polymer gel copolymerised by sodium acrylate (SA).

49. A probe as claimed in claim 1 wherein the sensing element comprises a hydrogel.

50. A probe as claimed in claim 1 wherein the optical fiber has a body compatible surface.

51. A probe as claimed in claim 1 wherein the fiber has a length and wherein the probe is provided with a polymer coating along said length.

52. A probe as claimed in claim 1 wherein the probe is sterilised.

53. A probe as claimed in claim 1 wherein the fibre at the sensing location or locations is provided within a rigid or semi-rigid tubular housing.

54. A probe as claimed in claim 53 wherein the housing is perforate.

55. A probe as claimed in claim 1 wherein the sensing location of the fiber is provided with a removable, retractable protective housing.

56. A probe as claimed in claim 1 wherein the diameter of the fiber core of the fiber probe is between 4 and 15 μ

m.

57. A probe as claimed in claim 56 wherein the diameter of the fiber core is 6 to 10 μ

m.

58. A probe as claimed in claim 57 wherein the fiber core diameter is approximately 8 μ

m.

59. A probe as claimed in claim 1 wherein the fiber cladding diameter is within the range 80 to 200 μ

m

60. A probe as claimed in claim 59 wherein the diameter of the fiber cladding is between 100 to 150 μ

m.

61. A probe as claimed in claim 60 wherein the fiber cladding diameter is approximately 125 μ

m

62. A probe as claimed in claim 1 comprising a protective sleeve or housing enclosing the sensing region of the probe, said protective sleeve or housing having a diameter of the order of 0.2 to 2 mm.

63. A probe as claimed in claim 2 wherein the mass of reactive material comprises a coating having a coating thicknesses of between 10 and 1000 μ

m.

64. A probe as claimed in claim 1 having an overall fibre optic probe length between 10 and 100 mm.

65. A probe as claimed in claim 1 wherein the probe is formed of a single fiber optic element.

66. A sensor or probe as claimed in claim 1 wherein the probe is formed of multiple axially connected fibre optic elements, wherein the length of the probe is between 20 and 150 mm.

69. A probe as claimed in claim 68 wherein the sensing element creates a radial and/or a longitudinal strain within the fiber in such a way as to change an optical response of the fiber.

70. A probe as claimed in claim 67 wherein said active fiber laser comprises a fiber having a fiber cladding and wherein said sensing location is provided with a sensing element in the form of a reactive coating which is disposed directly or indirectly on the fiber cladding, and wherein the coating is configured to create a strain within the fiber responsive to at least one body parameter to be measured, the strain providing a change in at least one detectable optical property of the fiber.

71. A probe as claimed in claim 70 wherein the coating is formed from one or more of a plurality of different materials, each material responsive to a selected physical or chemical parameter within the body.

72. A probe as claimed in claim 70 wherein the reactive coating is formed of a body compatible material such that the coating is able in use directly to contact a biological material within the body.

73. A probe as claimed in claim 70 further comprising a protective membrane arranged over the reactive coating, said membrane allowing measurement of a particular parameter but providing in use a barrier between said coating and a body material.

74. A probe as claimed in claim 73 wherein the membrane is arranged to allow selected target molecules to diffuse from the body side through to the coating material forming the sensing element.

75. A probe as claimed in claim 70 wherein the fiber has a fiber axis and the reactive coating is provided at a number of different regions spaced along the fiber axis.

76. A probe as claimed in claim 68 wherein the sensing element is coupled to the fiber at two or more axially spaced locations.

77. A probe as claimed in claim 76 wherein the sensing element comprises a cylinder fitted over the optical fiber and secured thereto at axially spaced locations.

78. A probe as claimed in claim 76 wherein the cylinder comprises a first end and a second end and wherein said first end engages a flange extending outwardly from the fiber, and said second end of the cylinder is suitably bonded to the fiber.

79. A probe as claimed in claim 68 wherein the sensing element is arranged to engage a piston carried by or coupled to the fiber.

80. A probe as claimed in claim 67 wherein a rigid or semi-rigid housing or a sleeve is provided around the fiber at the sensing location thereof, wherein a sensing element is provided in an annular cavity defined between the housing or sleeve and the fiber.

81. A probe as claimed in claim 80 wherein the measurand to be sensed is temperature and the sleeve or housing is formed of a material with good thermal conductivity.

82. A probe as claimed in claim 80 wherein the sensor is a chemical or biochemical sensor, and wherein the sleeve or housing is configured to allow the ingress of a target measurand.

83. A probe as claimed in claim 68 wherein the sensing element applies a sideways force on a sensing region of the fibre to establish a bending strain therein.

84. A probe as claimed in claim 83 comprising first and second sensing elements mounted within a housing, said first sensing element being arranged to urge a free end of the fibre in a first direction and said second sensing element being arranged to urge the free end of the fibre in a second direction, said second direction being opposite to the first direction.

85. A probe as claimed in claim 84 wherein said first sensing element is reactive to a particular chemical or biological substance, and the second sensing element is less sensitive to said particular chemical or biological substance but is otherwise of similar construction to the first sensing element.

86. A probe as claimed in claim 67 wherein the optical fiber is birefringent.

87. A probe as claimed in claim 86 wherein the fiber comprises one or more side holes at the sensing location.

88. A probe as claimed in claim 87 wherein a sensing element is provided in said side hole.

89. A probe as claimed in claim 88 wherein the fibre is provided with a membrane at a free end thereof allowing a chemical or biological substance to diffuse through the membrane so as to contact the sensing element material within the side-hole.

90. A probe as claimed in claim 68 wherein said sensing element comprises a reactive material immobilized on a solid support medium, said solid support medium acting as a selective element.

91. A probe as claimed in claim 68 wherein the sensing element comprises a reactive material dispersed or immobilized in a fluid or gel, wherein the fluid or gel swells or contracts in response to a target measurand.

92. A probe as claimed in claim 67 wherein a separate body compatible membrane is provided covering or enclosing the sensing location.

93. A probe as claimed in claim 1 wherein a coating of paint or bonding material such as a polymer gel network is provided at the sensing location.

94. A probe as claimed in any of claims 1 wherein a coating of a porous material such as sol-gel glass or ceramics is provided at the sensing location.

95. A probe as claimed in claim 68 wherein the sensing element comprises micro-spherical balls, provided with additives generating chemical selectivity for a selected group of molecules.

96. A probe as claimed in claim 68 wherein the sensing element comprises a hydrogel.

97. A probe as claimed in claim 67 wherein the sensing location of the fiber is provided with a removable, retractable protective housing.

183. A probe as claimed in claim 1 comprising an active fiber laser including said fiber.

184. A probe as claimed in claim 1 which comprises at least one sensing location including an active FBG laser or a passive FBG device providing a birefringent optical output or response dependent upon at least one parameter to be measured.

206. A sterile pack including one or more probes as claimed in claim 1.

207. A method of medical or biological treatment, analysis or diagnosis, involving the use of one or more probes as described in claim 1.

67. A body compatible fiber optic probe for invasive medical use which is configured to provide in at least one sensing location an active fiber laser providing a varying optical output in use dependent upon at least one parameter to be measured within a human or animal body.

68. A body compatible fiber optic probe for invasive medical use which is configured to provide in at least one sensing location an active fiber laser providing a varying optical output in use dependent upon at least one parameter to be measured within a human or animal body, said probe further comprising at said sensing location at least one sensing element comprising a mass of reactive material.

98. A body compatible fiber optic probe for invasive medical use which comprises at least one sensing location including an active FBG laser or a passive FBG device providing a birefringent optical output or response dependent upon at least one parameter to be measured within a human or animal body.

101. A probe as claimed in claim 98 wherein said fiber has a fibre cladding and wherein said sensing location is provided with a sensing element in the form of a reactive coating which is disposed directly or indirectly on the fiber cladding, and wherein the coating is configured to create a strain within the fiber responsive to at least one body parameter to be measured, the strain providing a change in at least one detectable optical property of the fiber.

102. A probe as claimed in claim 101 wherein the coating is formed from one or more of a plurality of different materials, each material responsive to a selected physical or chemical parameter within the body.

103. A probe as claimed in claim 102 wherein the reactive coating is formed of a body compatible material such that the coating is able in use directly to contact a biological material within the body.

104. A probe as claimed in claim 101 further comprising a protective membrane arranged over the reactive coating, said membrane allowing measurement of a particular parameter but providing in use a barrier between said coating and a body material.

105. A probe as claimed in claim 104 wherein the membrane is arranged to allow selected target molecules to diffuse from the body side through to the coating material forming the sensing element.

106. A probe as claimed in claim 101 wherein the fiber has a fiber axis and the reactive coating is provided at a number of different regions spaced along the fiber axis.

111. A probe as claimed in claim 98 wherein a rigid or semi-rigid housing or a sleeve is provided around the fiber at the sensing location thereof, wherein a sensing element is provided in an annular cavity defined between the housing or sleeve and the fiber.

112. A probe as claimed in claim 111 wherein the measurand to be sensed is temperature and the sleeve or housing is formed of a material with good thermal conductivity.

113. A probe as claimed in claim 111 wherein the sensor is a chemical or biochemical sensor, and wherein the sleeve or housing is configured to allow the ingress of a target measurand.

115. A probe as claimed in claim 114 comprising first and second sensing elements mounted within a housing, said first sensing element being arranged to urge a free end of the fibre in a first direction and said second sensing element being arranged to urge the free end of the fibre in a second direction, said second direction being opposite to the first direction.

116. A probe as claimed in claim 115 wherein said first sensing element is reactive to a particular chemical or biological substance, and the second sensing element is less sensitive to said particular chemical or biological substance but is otherwise of similar construction to the first sensing element.

117. A probe as claimed in claim 98 wherein said optical fiber comprises at least one side hole.

118. A probe as claimed in claim 117 wherein a sensing element is provided in said side hole.

119. A probe as claimed in claim 118 wherein the fibre is provided with a membrane at a free end thereof allowing a chemical or biological substance to diffuse through the membrane so as to contact the sensing element material within the side-hole.

127. A probe as claimed in claim 98 wherein the sensing location of the fiber is provided with a removable, retractable protective housing.

129. A probe as claimed in claim 128 wherein said fiber comprises a fiber core having one or more fiber Bragg gratings (FBG'"'"'s) written the fiber core.

130. A probe as claimed in claim 128 comprising an active fiber laser including said fiber.

131. A probe as claimed in claim 128 which comprises at least one sensing location including an active FBG laser or a passive FBG device providing a birefringent optical output or response dependent upon at least one parameter to be measured.

132. A probe as claimed in claim 128 wherein the coating is formed from one or more of a plurality of different materials, each material responsive to a selected physical or chemical parameter within the body.

133. A probe as claimed in claim 128 wherein the reactive coating is formed of a body compatible material such that the coating is able in use directly to contact a biological material within the body.

134. A probe as claimed in claim 128 further comprising a protective membrane arranged over the reactive coating, said membrane allowing measurement of a particular parameter but providing in use a barrier between said coating and a body material.

135. A probe as claimed in claim 134 wherein the membrane is arranged to allow selected target molecules to diffuse from the body side through to the coating material forming the sensing element.

136. A probe as claimed in claim 128 wherein the fiber has a fiber axis and the reactive coating is provided at a number of different regions spaced along the fiber axis.

137. A probe as claimed in claim 128 wherein the optical fiber is birefringent.

138. A probe as claimed in claim 137 wherein the fiber comprises one or more side holes at the sensing location.

139. A probe as claimed in claim 128 wherein said sensing element comprises a reactive material immobilized on a solid support medium, said solid support medium acting as a selective element.

140. A probe as claimed in claim 128 wherein the sensing element comprises a reactive material dispersed or immobilized in a fluid or gel, wherein the fluid or gel swells or contracts in response to a target measurand.

141. A probe as claimed in claim 128 wherein a separate body compatible membrane is provided covering or enclosing the sensing element.

142. A probe as claimed in claim 128 wherein the sensing element comprises a coating of paint or bonding material such as a polymer gel network.

143. A probe as claimed in claim 128 wherein the sensing element comprises a coating of a porous material such as sol-gel glass or ceramics.

144. A probe as claimed in claim 128 wherein the sensing element comprises micro-spherical balls, provided with additives generating chemical selectivity for a selected group of molecules.

145. A probe as claimed in claim 128 wherein the sensing element comprises a hydrogel.

146. A probe as claimed in claim 128 wherein the sensing location of the fiber is provided with a removable, retractable protective housing.

148. A probe as claimed in claim 147 wherein said fiber comprises a fiber core having one or more fiber Bragg gratings (FBG'"'"'s) written the fiber core.

149. A probe as claimed in claim 147 comprising an active fiber laser including said fiber.

150. A probe as claimed in claim 147 which comprises at least one sensing location including an active FBG laser or a passive FBG device providing a birefringent optical output or response dependent upon at least one parameter to be measured.

151. A probe as claimed in claim 147 wherein the optical fiber is birefringent.

152. A probe as claimed in claim 147 wherein said sensing element comprises a reactive material immobilized on a solid support medium, said solid support medium acting as a selective element.

153. A probe as claimed in claim 147 wherein the sensing element comprises a reactive material dispersed or immobilized in a fluid or gel, wherein the fluid or gel swells or contracts in response to a target measurand.

154. A probe as claimed in claim 147 wherein a separate body compatible membrane is provided covering or enclosing the sensing element.

155. A probe as claimed in claim 147 wherein the sensing element comprises a hydrogel.

156. A probe as claimed in claim 147 wherein the sensing element of the fiber is provided with a removable, retractable protective housing.

158. A probe as claimed in claim 157 wherein said fiber comprises a fiber core having one or more fiber Bragg gratings (FBG'"'"'s) written the fiber core.

159. A probe as claimed in claim 157 comprising an active fiber laser including said fiber.

160. A probe as claimed in claim 157 which comprises at least one sensing location including an active FBG laser or a passive FBG device providing a birefringent optical output or response dependent upon at least one parameter to be measured.

161. A probe as claimed in claim 157 wherein the sensing element is a solid or semi-solid material located within a cylinder.

162. A probe as claimed in claim 157 wherein the sensing element is a flowable liquid or gel which expands within the cylinder.

163. A probe as claimed in claim 157 wherein the probe is a sensor for chemical or biological material, and the cylinder is formed of a material provided with means to enable the molecules of the chemical or biological material to be sensed to permeate through the cylinder walls.

164. A probe as claimed in claim 157 wherein the piston/cylinder arrangement is acted on by first and second sensing elements arranged to apply force to the fiber in opposite directions, the first and second sensing elements each providing a similar response in relation to a first set of parameters, but a different response in relation to a selected measurand.

165. A probe as claimed in claim 157 wherein the optical fiber is birefringent.

166. A probe as claimed in claim 157 wherein said sensing element comprises a reactive material immobilized on a solid support medium, said solid support medium acting as a selective element.

167. A probe as claimed in claim 157 wherein the sensing element comprises a reactive material dispersed or immobilized in a fluid or gel, wherein the fluid or gel swells or contracts in response to a target measurand.

168. A probe as claimed in claim 157 wherein a separate body compatible membrane is provided covering or enclosing the sensing element.

169. A probe as claimed in claim 157 wherein the sensing element comprises a hydrogel.

170. A probe as claimed in claim 157 wherein the sensing location of the fiber is provided with a removable, retractable protective housing.

172. A probe as claimed in claim 171 wherein said fiber comprises a fiber core having one or more fiber Bragg gratings (FBG'"'"'s) written the fiber core.

173. A probe as claimed in claim 171 comprising an active fiber laser including said fiber.

174. A probe as claimed in claim 171 which comprises at least one sensing location including an active FBG laser or a passive FBG device providing a birefringent optical output or response dependent upon at least one parameter to be measured.

175. A probe as claimed in claim 171 wherein said sensing element comprises a reactive material immobilized on a solid support medium, said solid support medium acting as a selective element.

176. A probe as claimed in claim 171 wherein the sensing element comprises a reactive material dispersed or immobilized in a fluid or gel, wherein the fluid or gel swells or contracts in response to a target measurand.

177. A probe as claimed in claim 171 wherein a separate body compatible membrane is provided covering or enclosing the sensing element.

178. A probe as claimed in claim 171 wherein the sensing element comprises a hydrogel.

179. A probe as claimed in claim 171 wherein the housing is perforate

180. A probe as claimed in claim 171 wherein the sensing location of the fiber is provided with a removable, retractable protective housing.

182. A probe as claimed in claim 181 wherein said fiber comprises a fiber core having one or more fiber Bragg gratings (FBG'"'"'s) written the fiber core.

185. A probe as claimed in claim 181 wherein the fibre is provided with a membrane at a free end thereof allowing a chemical or biological substance to diffuse through the membrane so as to contact the sensing element material within the side-hole.

186. A probe as claimed in claim 181 wherein said sensing element comprises a reactive material immobilized on a solid support medium, said solid support medium acting as a selective element.

187. A probe as claimed in claim 181 wherein the sensing element comprises a reactive material dispersed or immobilized in a fluid or gel, wherein the fluid or gel swells or contracts in response to a target measurand.

188. A probe as claimed in claim 181 wherein a separate body compatible membrane is provided covering or enclosing the sensing element.

189. A probe as claimed in claim 181 wherein the sensing element comprises a hydrogel.

190. A probe as claimed in claim 181 wherein the sensing location of the fiber is provided with a removable, retractable protective housing.

192. A probe as claimed in claim 191 wherein the at least one sensing element comprises a mass of reactive material.

193. A probe as claimed in claim 191 wherein said fiber comprises a fiber core having one or more fiber Bragg gratings (FBG'"'"'s) written the fiber core.

194. A probe as claimed in claim 191 comprising an active fiber laser including said fiber.

195. A probe as claimed in claim 192 which comprises at least one sensing location including an active FBG laser or a passive FBG device providing a birefringent optical output or response dependent upon at least one parameter to be measured.

196. A probe as claimed in claim 191 comprising first and second sensing elements mounted within a housing, said first sensing element being arranged to urge a free end of the fibre in a first direction and said second sensing element being arranged to urge the free end of the fibre in a second direction, said second direction being opposite to the first direction.

197. A probe as claimed in claim 196 wherein said first sensing element is reactive to a particular chemical or biological substance, and the second sensing element is less sensitive to said particular chemical or biological substance but is otherwise of similar construction to the first sensing element.

198. A probe as claimed in claim 191 wherein the optical fiber is birefringent.

199. A probe as claimed in claim 191 wherein said sensing element comprises a reactive material immobilized on a solid support medium, said solid support medium acting as a selective element.

200. A probe as claimed in claim 191 wherein the sensing element comprises a reactive material dispersed or immobilized in a fluid or gel, wherein the fluid or gel swells or contracts in response to a target measurand.

201. A probe as claimed in claim 191 wherein a separate body compatible membrane is provided covering or enclosing the sensing element.

202. A probe as claimed in claim 191 wherein the sensing element comprises a hydrogel.

203. A probe as claimed in claim 191 wherein the sensing location of the fiber is provided with a removable, retractable protective housing.

99. A body compatible fiber optic probe for invasive medical use which comprises at least one sensing location including an active FBG laser or a passive FBG device providing a birefringent optical output or response dependent upon at least one parameter to be measured within a human or animal body, said probe further comprising a sensing element at said sensing location, said sensing element comprising a mass of reactive material.

100. A probe as claimed in claim 99 wherein the sensing element creates a radial and/or a longitudinal strain within the fiber in such a way as to change an optical response of the fiber.

107. A probe as claimed in claim 99 wherein the sensing element is coupled to the fiber at two or more axially spaced locations.

108. A probe as claimed in claim 107 wherein the sensing element comprises a cylinder fitted over the optical fiber and secured thereto at axially spaced locations.

109. A probe as claimed in claim 108 wherein the cylinder comprises a first end and a second end and wherein said first end engages a flange extending outwardly from the fiber, and said second end of the cylinder is suitably bonded to the fiber.

110. A probe as claimed in claim 99 wherein the sensing element is arranged to engage a piston carried by or coupled to the fiber.

114. A probe as claimed in claim 99 wherein the sensing element applies a sideways force on a sensing region of the fibre to establish a bending strain therein.

120. A probe as claimed in claim 99 wherein said sensing element comprises a reactive material immobilized on a solid support medium, said solid support medium acting as a selective element.

121. A probe as claimed in claim 99 wherein the sensing element comprises a reactive material dispersed or immobilized in a fluid or gel, wherein the fluid or gel swells or contracts in response to a target measurand.

122. A probe as claimed in claim 99 wherein a separate body compatible membrane is provided covering or enclosing the sensing element.

123. A probe as claimed in claim 99 wherein the sensing element comprises a coating of paint or bonding material such as a polymer gel network.

124. A probe as claimed in claim 99 wherein the sensing element comprises a coating of a porous material such as sol-gel glass or ceramics.

125. A probe as claimed in claim 99 wherein the sensing element comprises micro-spherical balls, provided with additives generating chemical selectivity for a selected group of molecules.

126. A probe as claimed in claim 99 wherein the sensing element comprises a hydrogel.

128. A body compatible fiber optic probe for invasive medical use, wherein at least one sensing location of the fiber is provided with a reactive coating configured to create strain within the fiber responsive to at least one body parameter to be measured, such strain providing a change in at least one detectable optical property of the fiber.

147. A fiber optic sensor comprising a sensing element coupled to the fiber at two or more axially spaced locations thereon, and wherein the sensing element is configured to provide a generally axially directed compressive or extensive force on the fiber between such locations in response to a particular parameter to be measured, such a force providing a changing optical response of the fiber.

157. A fiber optic sensor in which at least one region of the optical fiber provides a varying optical response depending on axial compressive or extensive strain within the fiber, there being a piston and/or cylinder arrangement including a sensing element coupled to said region of the fiber and arranged to provide such strain in response to a parameter to be measured.

171. A fiber optic sensor whose optical response changes at one or more measuring locations in response to generally radially applied stress, the fiber being surrounded at such location or locations by a rigid or semi-rigid housing or sleeve, a reactive sensing element being provided between the sleeve and the fiber, the element being arranged to swell in response to a measurand in order to provide strain within the fiber and to change its optical response.

181. An optical fiber sensor comprising an optical fiber provided with one or more side-holes adjacent at least one sensing region of the fiber, a reactive sensing element provided in one or more side-holes such that the element changes volume to create strain in the fiber in response to one or more measurands to be detected, such strain changing at least one detectable optical property of the fiber.

191. An optical fiber sensor comprising an optical fiber provided with at least one sensing region and a sensing element wherein the sensing element is configured to apply a sideways force on a sensing region of the fiber to establish a bending strain therein causing a change in a detectable optical property or properties of the fiber.

204. A body compatible fiber optic sensor probe for invasive medical use, the probe including:

a fiber;

a sensing location at which the fiber is configured to provide at least one detectable changeable optical property responsive to a strain within the fiber;

at least one sensing element which undergoes a volumetric change in response to an in body parameter to be sensed;

wherein the sensing element is coupled to the fiber in such a way that the volumetric change induces the strain within the fiber so as to vary the detectable changeable optical property and wherein said fiber comprises a pair of pi phase-shifted fiber Bragg gratings.

205. A body compatible fiber optic probe for invasive medical use comprising a sensor element formed from a polymer gel material whose volume changes in response to at least one body parameter to be measured, such change in volume creating strain within the fiber to change at least one detectable optical property thereof.

208. A method of medical or biological treatment, analysis or diagnosis, involving the use in vivo, ex-vivo or in vitro of an optical fiber sensor, such sensor having at least one sensing location having a sensing element coupled to the fiber, and the method further comprising detecting a changing optical property of the fiber dependent on a parameter which causes a volumetric change in the sensing element, such volumetric change creating strain within the fiber whereby the change in optical response is created.

209. A method of medical or biological treatment, analysis or diagnosis, in which an optical fiber sensor is exposed to biochemical or biological material, such sensor including at least one active fiber laser providing an output which changes depending on at least one parameter to be measured relating to the material.