Optical Sensor Module Research Articles

Fiber optic oxygen sensor based on phosphorescence quenching of erythrosin B trapped in silica-gel glasses

Experimental results from a phosphorescence-based fiber-optical oxygen sensor are presented. The optical oxygen sensor module has overall dimensions of 6 × 6 × 12 mm 3. Erythrosin B immobilized in sol–gel silica, which showed strong phosphorescence quenching by oxygen, was used in the sensor probe. Oxygen sensing is effective from 0.014 to 600 mbar. On account of the long phosphorescence lifetime (∼0.28 ms) and high phosphorescence yield (∼2%) of erythrosin B in sol–gel silica at room temperature, the sensitivity of the sensor improves by a factor of 10 as compared to transition-metal complex-based optical fiber oxygen sensors. The phosphorescence quenching effect is highly selective to oxygen. The sensor is inert to commonly found gases such as nitrogen and argon. Time-decay of phosphorescence is also studied.

Compact integrated optical immunosensor using replicated chirped grating coupler sensor chips

A novel compact multichannel integrated optical sensor module isdescribed. Its performance is demonstrated by measurement of the mass adsorption of an analyte molecule to the transducer surface by refractometry in an immunosensor experiment. The signal transduction is achieved by means of chirped grating couplers, which allow simple yet highly functional sensor modules to be built. The experiments were performed with high-sensitivity replicated polycarbonate TiO(2) waveguide sensor chips for detecting the binding of rabbit immunoglobulin to immobilized protein A. Aresolution of ?3 pg/mm(2) surface mass coverage was obtained in a dual-channel module with size 10 cm x 10 cm x10 cm.

Compact integrated optical immunosensor using replicated chirped grating coupler sensor chips

A novel compact multichannel integrated optical sensor module isdescribed. Its performance is demonstrated by measurement of the mass adsorption of an analyte molecule to the transducer surface by refractometry in an immunosensor experiment. The signal transduction is achieved by means of chirped grating couplers, which allow simple yet highly functional sensor modules to be built. The experiments were performed with high-sensitivity replicated polycarbonate TiO(2) waveguide sensor chips for detecting the binding of rabbit immunoglobulin to immobilized protein A. Aresolution of ?3 pg/mm(2) surface mass coverage was obtained in a dual-channel module with size 10 cm x 10 cm x10 cm.

Optical oxygen sensor instrumentation based on the detection of luminescence lifetime

Optical oxygen sensors are mainly based on the principle of luminescence quenching. In contrast to already existing intensity-based systems, the measurement of the luminescence lifetime provides certain advantages, such as insensitivity to photobleaching or leaching of the dye, or changes in the intensity of excitation light. This facilitates the use of simple optical systems or optical fibres. A new family of oxygen-sensitive dyes, the porphyrin-ketones, has been introduced, which exhibits favorable spectral properties and decay times in the order of tens and hundreds of microseconds. This allows the use of simple opto-electronic circuitry and low-cost processing electronics. An optical oxygen sensor module has been developed with the dimensions of only 120 × 60 × 30 mm. The prototype is based on the measurement of the decay time of the luminophore by measuring the phase shift between the square-wave excitation and the detected square-wave of the emission coming from the sensor. The instrument is based on semiconductor devices (light-emitting diodes, photodiodes) and may be used for the detection of oxygen in gaseous or liquid samples. The measurement range of the device is from 0 to 200 hPa oxygen partial pressure with a resolution of < 1 hPa over the whole measurement range. The overall measurement accuracy of < ± 1 hPa has been obtained for periods of 24 h of continuous measurement in a thermostatted environment. The sensor response times t 90 are typically < 1 s for gases and 0.5 to 5 min for liquid samples.

Planar waveguide ion-selective sensors

A potassium ion-selective planar waveguide total internal reflection (TIR) mode optical sensor was prepared for flow injection application by casting thin film optode membranes onto a glass substrate. For this sensor, a potassium selective ionophore is incorporated in plasticized polyvinyl chloride film sensitized with a hydrogen selective ionophore. The sensor response to potassium ion is determined by measuring the attenuation of a HeNe laser propagated in this thin film device. The laser was coupled into and out of the sensor using grating couplers providing an inexpensive, environmentally stable sensor. The sensitivity of the waveguide based flow injection device is approximately 0.05 mM K +, while the rate of analysis is about 180 samples per hour.

Miniaturized luminescence lifetime-based oxygen sensor instrumentation utilizing a phase modulation technique

Optical oxygen sensors are mainly based on the principle of luminescence quenching. In contrast to already existing intensity-based systems, the measurement of the luminescence lifetime provides certain advantages, such as insensitivity to photobleaching or leaching of the dye or changes in the intensity of excitation light. This facilitates the use of simple optical fibers. Phase measurement techniques have shown to be a powerful tool for indirect measurement of luminescence lifetimes. Here, dyes with luminescence decay times in the order of tens or hundreds of microseconds allow the use of simple opto-electronic circuitry and low-cost processing electronics. An optical oxygen sensor module has been developed with the dimensions of only 120 × 60 × 30 mm. The instrument is based on the measurement of the decay time of the luminophore by measuring the phase shift between the square-wave excitation and the detected square-wave of the emission coming from the sensor. The instrument is based on semiconductor devices (light-emitting diodes, photodiodes) and may be used for the detection of oxygen in gaseous or liquid samples. Platinum(II) octaethylporphyrin-ketone, which is incorporated in an oxygen-permeable polymer and which has an unquenched lifetime of approximately 60 μs, is used as the oxygen-sensitive dye. The typical measurement range of the device is from 0 to 200 hPa oxygen partial pressure with a resolution of <1 hPa over the whole measurement range. Measurement accuracy of < ± 1 hPa has been obtained for periods of 24 h of continuous measurement. The sensor response times t90 are typically <1 s for gases and 1–5 min for liquid samples.

Fiber optic biosensor for fluorimetric detection of DNA hybridization

Single stranded deoxyribonucleic acid (ssDNA) thymidylic acid icosanucleotides (dT 20) were grown onto optical fibers. The fibers were first derivatized with γ-aminopropyltriethoxysilane (APTEs) onto which a spacer arm of 1,10 decanediol bis-succinate terminated with 5′-O-dimethoxytrityl-2′-deoxythymidine was covalently attached. The synthetic route used to grow the ssDNA was the well established solid-phase phosphoramidite methodology. The covalently immobilized oligormers were able to hybridize with available complementary ssDNA (cDNA) which was introduced into the local environmnet to forum double stranded DNA (dsDNA). This event was detected by the use of the fluorescent DNA stain ethidium bromide (EB). The sampling configuration utilized total internal reflection of optical radiation within the fiber, resulting in an intrinsic mode optical sensor. The non-optimized procedure used standard hybridization assay techniques to provide a detection limit of 86 ng ml −1 cDNA, a sensitivity of 83% fluorescence intensity increase per 100 ng ml −1 of cDNA initially present, with a hybridization analysis time of 46 min. The sensor has been observed to sustain activity after prolonged storage times (3 months) and harsh washing conditions (sonication).