Microfluidic Enhanced Fabry-Perot Etalon Based Optical Biosensor for the Detection of Biological Substances in Liquid with Refractive Index Measurement

A new microfluidic optical biosensor was demonstrated for refractive index measurements with high sensitivity and accuracy in the range of few micrometers liquid channels utilizing a Fabry-Perot cavity formed between two reflective semitransparent surfaces. The transmitted light through the cavity forms interference peaks in the transmission spectrum which is dependent upon the refractive index of the fluid in the microfluidic channel. We demonstrate the biosensor using Fabry-Perot to provide high accuracy and sensitivity with real-time measurement. The sensor can resolve refractive index changes with the shift of peak wavelength of transmitted spectrum. In our Fabry- Perot etalon based biosensor, two thin film coated glass substrates were used to detect the biological substances in liquid. Silver thin film is used on the glass substrates as the semitransparent layer to reflect the light repeatedly and cause interference of light. The SiO2 layer coated on the silver layer created a hydrophilic surface in addition to protecting the silver layer from oxidation. The hydrophilic behavior of the SiO2 films together with a capillary action allowed the tested liquids to easily flow into and wet the cavity between the two pieces of glass substrates. The device was utilized for measurement of the refractive index of sugar, glucose, potassium and sodium solution of different concentration at room temperature. The contact angle measurer, spectrophotometer and Dektak surface profilometer were used for characterization of the sensor. The proposed sensor has high refractive index sensitivity, fast response, accurate, good linear response, and easy fabrication with super-hydrophilic microfluidic active layer. The result obtained from the experiment are in good agreement with the theoretical result and other reported result

Efficacy of Methotrexate in Combination with Antioxidant Vitamins (A, C & E) versus Methotrexate alone in the Treatment of Rheumatoid Arthritis

Background: There is evidence that oxidative stress plays an important role in autoimmune diseases, such as rheumatoid arthritis (RA). Despite the supporting evidence for a beneficial effect of antioxidants on clinical characteristics of RA, the right balance for optimal effectiveness of antioxidants is largely unknown. A study was designed to determine the potential beneficial effects of antioxidant intervention on clinical parameters of RA.Methods: Randomized clinical trial of 152 patients with positive rheumatoid factor (RF) and a Disease Activity Score (DAS 28) higher than 3.2 were enrolled in the study. Patients were divided into two groups (Group A and Group B) randomly and group A received methotrexate and antioxidant vitamins (A, C and E in a fixed dose) and group B methotrexate only. They were followed up for three visits (baseline, 10th week and 14th week). The intervention was stopped after 10 weeks and was followed by a ‘wash-out’ period of 4 weeks. At baseline, 10th week and 14th week patient’s condition were assessed by means of DAS-28 score. P- Value less than <0.05 was considered significant.Results: The numbers of swollen and tender joints were significantly reduced and general health was improved reflected by improved DAS-28 score at 10th week.The antioxidant effect was considered beneficial as compared to the scores of 1st visit at baseline; the DAS-28 score was significantly reduced at 2nd visit at 10th week. Increment of the DAS-28 score among the group A patients who were on antioxidant up to10 weeks, after the “wash-out period” of four weeks i.e. at 14th week confirmed a significant relation between changes in clinical condition and antioxidants.Conclusion: This study was designed to assess the potential beneficial effect of antioxidants (Vitamin A, C and E) in combination with methotrexate in the treatment of RA

Highly Sensitive Detection of Biological Substances using Microfluidic Enhanced Fabry-Perot Etalon-Based Optical Biosensors

A microfluidic based optical biosensor is introduced to detect concentrations of biochemical substances in solution using refractive index measurement with high sensitivity and accuracy. The sensor consists of a liquid channel forming a Fabry-Perot cavity between two semitransparent Ag/SiO_2 reflective surfaces. Light is transmitted through the cavity to construct interference peaks in the transmission spectra which depend on the refractive index of the test samples in the channel. The refractive index of glucose, potassium chloride, and sodium chloride solutions is measured in different concentrations. Continuous change in refractive index is resolved by observing the peak wavelength shift in the transmitted spectrum. The sensor is characterized using the contact angle measurer, surface profilometer, and spectrophotometer. The proposed Fabry-Perot etalon biosensor shows real time linear responses as well as high accuracy and sensitivity of 10^(-3) refractive index per percent of glucose, 1.4 × 10^(-3) and 1.8 × 10^(-3) refractive index per percent of KCl and NaCl solution, respectively

Highly Sensitive Detection of Biological Substances using Microfluidic Enhanced Fabry-Perot Etalon-Based Optical Biosensors

A microfluidic based optical biosensor is introduced to detect concentrations of biochemical substances in solution using refractive index measurement with high sensitivity and accuracy. The sensor consists of a liquid channel forming a Fabry-Perot cavity between two semitransparent Ag/SiO_2 reflective surfaces. Light is transmitted through the cavity to construct interference peaks in the transmission spectra which depend on the refractive index of the test samples in the channel. The refractive index of glucose, potassium chloride, and sodium chloride solutions is measured in different concentrations. Continuous change in refractive index is resolved by observing the peak wavelength shift in the transmitted spectrum. The sensor is characterized using the contact angle measurer, surface profilometer, and spectrophotometer. The proposed Fabry-Perot etalon biosensor shows real time linear responses as well as high accuracy and sensitivity of 10^(-3) refractive index per percent of glucose, 1.4 × 10^(-3) and 1.8 × 10^(-3) refractive index per percent of KCl and NaCl solution, respectively

Multichannel Fiber-Optic Silicon Fabry–Pérot Interferometric Bolometer System for Plasma Radiation Measurements

A single-channel fiber-optic bolometer system based on a high-finesse silicon Fabry–Pérot interferometer (FPI) was previously reported, intended to measure plasma radiation from the magnetically confined fusion chamber. Recently, we developed a multichannel fiber-optic bolometer system with five bolometers multiplexed using a coarse wavelength division multiplexer (CWDM) and interrogated with a white-light system involving a superluminescent light-emission diode source and a high-speed spectrometer. One of the bolometers was used as the reference bolometer to compensate for the ambient temperature variations, and the other four bolometers were used for radiation measurement. The bolometers have a simple structure with a silicon pillar at the end of the single-mode fiber and a gold disk on the other side of the silicon pillar. They are also easy to fabricate without stringent requirements on the optical alignment. Analysis of the system optimization was performed to improve the noise performance and to mitigate the vibration effect that may present in the practical application. The system had a significantly enhanced measurement range compared to the previous high-finesse FPI bolometer system for measuring radiation. Test results performed in air using a 405 nm laser as the radiation source showed that the temperature resolution and the noise-equivalent power density of the sensing bolometers connected to each channel of the CWDM were, respectively, ~0.4 mK and ~0.1 W/m2, with a time constant of ~220 ms, which is comparable to the previous more complicated fiber-optic bolometer systems based on high-finesse FPIs that were interrogated using wavelength-scanning lasers

バングラデシュのフィラリア症重症化に 関わる生活環境・職業性因子

第７回南アジアにおける自然環境と人間活動に関する研究集会 : インド亜大陸・インドシナの自然災害と人間活動, 京都大学防災研究所大会議室S519D, 2012/02/04-0