Ex-Vivo Measurement of the pH in Aqueous Humor Samples by a Tapered Fiber-Optic Sensor

A practical demonstration of pH measurement in real biological samples with an in-house developed fiber-optic pH sensor system is presented. The sensor uses 8-hydroxypyrene-1,3,6-trisulfonate (HPTS) fluorescent dye as the opto-chemical transducer. The dye is immobilized in a hybrid sol-gel matrix at the tip of a tapered optical fiber. We used 405 nm and 450 nm laser diodes for the dye excitation and a photomultiplier tube as a detector. The sensor was used for the measurement of pH in human aqueous humor samples during cataract surgery. Two groups of patients were tested, one underwent conventional phacoemulsification removal of the lens while the other was subjected to femtosecond laser assisted cataract surgery (FLACS). The precision of the measurement was ±0.04 pH units. The average pH of the aqueous humor of patients subjected to FLACS and those subjected to phacoemulsification were 7.24 ± 0.17 and 7.31 ± 0.20 respectively.

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Sol-Gel and RF Sputtering Thin Film Coatings for Fiber Optic Sensor Applications

MRS Proceedings ◽

10.1557/proc-244-287 ◽

1991 ◽

Vol 244 ◽

Author(s):

M. R. Shahriari ◽

J. Y. Ding ◽

C. M. Wang ◽

C. H. Lin ◽

G. H. Sigel

Keyword(s):

Thin Film ◽

Optical Waveguides ◽

Fiber Optic ◽

Sol Gel ◽

Rf Sputtering ◽

Silica Matrix ◽

Hydrogen Gas ◽

Fiber Optic Sensor ◽

Sensor Applications ◽

Optic Sensor

ABSTRACTThin film coating techniques appear to have many advantages over other techniques for immobilization and incorporation of chemical indicators to optical waveguides in developing dye based fiber optic chemical sensors. We have fabricated thin films of composites by using sol-gel and RF sputtering techniques. Different organic and inorganic indicators were immobilized in these films and incorporated into optical waveguides for sensor applications. A fiber optic pH sensor has been developed by introducing pH indicators into a silica matrix and coated as a thin film onto a porous glass fiber by a sol-gel technique. Also, a hydrogen gas fiber optic sensor has been developed by using a RF sputtered WO3/Pd coated porous optical fiber.

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Chromophore Dynamics in Sol-Gel Glasses and Xerogel Clad Fiber Optic Sensors

MRS Proceedings ◽

10.1557/proc-346-579 ◽

1994 ◽

Vol 346 ◽

Cited By ~ 1

Author(s):

Drew L'Esperance ◽

Clarice A. Browne ◽

Eric L. Chronister

Keyword(s):

Energy Transfer ◽

Fiber Optic ◽

Rotational Diffusion ◽

Sol Gel ◽

Fiber Optic Sensors ◽

Fiber Optic Sensor ◽

Time Resolved ◽

Optic Sensor ◽

Sensor Device ◽

Gel Glasses

ABSTRACTTime-resolved depolarization measurements are used to investigate rotational diffusion and optical energy transfer dynamics of chromophores incorporated into silica and aluminosilica solutions, gels, and glasses. The use of an organically doped sol-gel clad waveguide as a novel intrinsic fiber optic sensor device is also demonstrated, and advantages of time-resolved detection of the fiber optic sensor are illustrated.

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Fiber Optic Sensor for Real-time Monitoring of Freezing–Thawing Cycle in Cryosurgery

Applied Sciences ◽

10.3390/app10031053 ◽

2020 ◽

Vol 10 (3) ◽

pp. 1053

Author(s):

Dimosthenis Spasopoulos ◽

George Rattas ◽

Archontis Kaisas ◽

Thomas Dalagiannis ◽

Ioannis D. Bassukas ◽

...

Keyword(s):

Real Time ◽

Optical Transmission ◽

Fiber Optic ◽

Expert Knowledge ◽

Ex Vivo ◽

Fiber Optic Sensor ◽

Real Time Monitoring ◽

Fiber Array ◽

Optic Sensor ◽

Optical Fiber Array

Cryosurgery/cryotherapy is a widely used, freezing–thawing technique for the renewal or destruction of pathological tissues by applying localized rapid cooling; however, it still relies on the subjective “expert knowledge” of the physicians without, up to now, real-time monitoring of the treatment. This work focused on assessing the depth of freezing using optical transmission and backscattering measurements from frozen/unfrozen porcine ex-vivo skin samples. An optical fiber-array sensor was subsequently developed to determine the depth of freezing and the associated kill zone during freeze–thawing cycles with sub-millimeter accuracy within the skin tissue.

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