02002nas a2200205 4500008004100000022001400041245010600055210006900161260000900230300001200239490000700251520129400258100002101552700001601573700002001589700002001609700001801629700002401647856012501671 2019 eng d a0740-322400aFiber optic Fabry-Perot interferometer sensor: an efficient and fast approach for ammonia gas sensing0 aFiber optic FabryPerot interferometer sensor an efficient and fa cMAR  a684-6890 v363 a

In this work, we propose and demonstrate a Fabry-Perot-interferometer-based polydimethylsiloxane (PDMS) and poly(methyl methacrylate) (PMMA)-composite-coated optical sensor for ammonia and volatile organic compounds (VOCs) detection at room temperature. The principle of sensing is based on change in the cavity length of the FP cavity in the presence of varied concentrations of gases, which results in changes in the total reflectance due to the shift in wavelength of an interference pattern. The sensing composite material was coated on a single-mode optical fiber by using a simple dip-coating technique and explored it for sensing. The ammonia and VOCs measurements were performed for concentrations ranging from 5 to 500 ppm. The corresponding sensitivity and limit of detection of the developed sensor for ammonia gas detection was observed of the order of around 4.16 pm/ppm and 4.8 ppm, respectively. The response and recovery times of the sensor were found to be of the order of 50 s and 10 s, respectively, for the ammonia gas. This sensor provides a simple, cost-effective, highly sensitive, and repeatable approach to measure ammonia gas and other VOCs at room temperature and could fulfill the demands of industrial applications. (C) 2019 Optical Society of America

1 aKanawade, Rajesh1 aKumar, Ajay1 aPawar, Dnyandeo1 aLate, Dattatray1 aMondal, Samir1 aSinha, Ravindra, K. uhttps://library.ncl.res.in/content/fiber-optic-fabry-perot-interferometer-sensor-efficient-and-fast-approach-ammonia-gas02301nas a2200253 4500008004100000020004100041245008500082210006900167260006500236520141300301653001501714653002201729653001501751653001901766653002501785100001601810700001801826700001801844700002101862700002001883700001201903700001201915856012001927 2022 eng d a978-1-5106-4740-4; 978-1-5106-4739-800aSkin mimicking solid optical tissue phantom fulfillment and its characterization0 aSkin mimicking solid optical tissue phantom fulfillment and its  a1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USAbSPIE3 a

Skin mimicking optical tissue phantoms are widely used in diagnostics systems for characterization, optimization, routine calibration and validation. In general, solid phantoms are more preferred in comparison to liquid phantoms. Therefore, our aim is to prepare and characterize the solid tissue phantoms having skin equivalent optical properties. In this work, we have used epoxy resin and hardener as a base material and titanium oxide (TiO2) nanoparticles and ink as a scatterer and absorber media, respectively. The total transmission (Tt), collimated transmission (Tc), and diffuse reflectance (Rd) spectra of the developed phantoms were measured with an integrating sphere installed in UV-VIS spectrometer within the wavelength range 400-700 nm. To characterize the optical properties such as absorption (mu(a)), reduced scattering (mu(s)'), and anisotropy factor (g) of the developed tissue phantoms, the numerical model based on Inverse Adding Doubling (IAD) has been used. With various concentrations of absorber and scatterer, a calibration curve was prepared. The calculated experimental optical properties from IAD matched with the predicted intrinsic optical properties of the skin. Thus, the preliminary results suggest that the recipe used in this study may be used as an alternative approach to developing skin mimicking solid optical phantom for diagnostics system applications.

10aAbsorption10aanisotropy factor10ascattering10askin mimicking10asolid tissue phantom1 aKumar, Ajay1 aHinge, Sarika1 aDixit, Hemant1 aKanawade, Rajesh1 aKulkarni, Gauri1 aChoi, B1 aZeng, H uhttps://library.ncl.res.in/content/skin-mimicking-solid-optical-tissue-phantom-fulfillment-and-its-characterization02608nas a2200217 4500008004100000245014200041210006900183260000800252300000700260490000600267520182300273100001802096700001602114700002102130700002002151700002302171700002102194700002302215700002302238856012902261 2023 eng d00aResponse of cardiac pulse parameters in humans at various inclinations via 360° rotating platform for simulated microgravity perspective0 aResponse of cardiac pulse parameters in humans at various inclin cJUL a540 v93 a

On the Earth, the human body is designed and adapted to function under uniform gravitational acceleration. However, exposure to microgravity or weightlessness as experienced by astronauts in space causes significant alterations in the functioning of the human cardiovascular system. Due to limitations in using real microgravity platforms, researchers opted for various ground-based microgravity analogs including head-down tilt (HDT) at fixed inclination. However, in the present study, an investigation of response of various cardiac parameters and their circulatory adaptation in 18 healthy male subjects was undertaken by using an indigenously developed 360 & DEG; rotating platform. Cardiac pulse was recorded from 0 & DEG; to 360 & DEG; in steps of 30 & DEG; inclination using piezoelectric pulse sensor (MLT1010) and associated cardiac parameters were analyzed. The results showed significant changes in the pulse shape while an interesting oscillating pattern was observed in associated cardiac parameters when rotated from 0 & DEG; to 360 & DEG;. The response of cardiac parameters became normal after returning to supine posture indicating the ability of the cardiovascular system to reversibly adapt to the postural changes. The observed changes in cardiac parameters at an inclination of 270 & DEG;, in particular, were found to be comparable with spaceflight studies. Based on the obtained results and the proposed extended version of fluid redistribution mechanism, we herewith hypothesize that the rotation of a subject to head down tilt inclination (270 & DEG;) along with other inclinations could represent a better microgravity analog for understanding the cumulative cardiac response of astronauts in space, particularly for short duration space missions.

1 aJagtap, Sagar1 aKumar, Ajay1 aMahale, Bhoopesh1 aDixit, Jyotsana1 aKalange, Ashok, E.1 aKanawade, Rajesh1 aGangal, Shashikala1 aVidyasagar, Pandit uhttps://library.ncl.res.in/content/response-cardiac-pulse-parameters-humans-various-inclinations-360%C2%B0-rotating-platform02861nas a2200241 4500008004100000022001400041245016700055210006900222260000900291300001100300490000700311520196300318653002402281653003702305653001402342653004102356653001902397100001602416700002302432700002002455700002102475856012302496 2024 eng d a0091-328600aFabrication and evaluation of a spatially resolved fiber-optic probe for diffuse reflectance measurement for noninvasive diabetic foot ulcer diagnosis perspective0 aFabrication and evaluation of a spatially resolved fiberoptic pr cAPR  a0441030 v633 a

Timely diagnosis and monitoring of wound progression or healing are key to improving the long-term outcome of diabetic foot ulcers (DFU). Diffuse reflectance spectroscopy (DRS) has the potential to noninvasively diagnose the DFU in real time, as it detects changes in local blood volume fraction and oxygenation state level that occur when tissue becomes diseased or ulcerated. Since foot soles have a thicker epidermis and deeper blood vessels/capillaries than other parts of the body, a spatially resolved fiber-optic probe (SRFP) is needed to detect the optimal spatially resolved diffuse reflectance (SRDR) signal from the local site of the ulcer for DFU diagnosis. Therefore, herein, an SRFP consisting of a linear array of seven 400-mu m fibers with detector-source (D-S) fiber separation (rho) ranging from 0.8 to 4.8 mm was designed, fabricated, tested, and evaluated for SRDR measurement from a standard reflectance plate of barium sulfate (BaSO4) and foot sole of 27 healthy human subjects. The variation in SRDR spectra for each detector and source fiber pair measured with BaSO4 was found to be less than 1.6%. In-vivo measurements from the foot sole demonstrate that the fabricated probe has the ability to spatially resolve and distinguish the SRDR spectra from sites, namely, the fifth metatarsal, ball of great joint, calcaneum, and great toe. Experimentally and theoretically, the detector and source fiber pair of rho=1.6 and 2.4 mm were optimal for SRDR measurements from a human foot. To evaluate and validate the performance of SRFP in a context relevant to DFU diagnosis, further SRDS measurements were performed on the solid tissue phantoms that mimic the optical properties of the normal and diabetic foot sole, and their results are statistically found different. Preliminary results suggest that developed SRFP can be explored for DRS measurement from foot ulcer patients to confirm its potential clinical applicability.

10adiabetic foot ulcer10adiffuse reflectance spectroscopy10afoot sole10aspatially resolved fiber-optic probe10atissue phantom1 aKumar, Ajay1 aHattale, Gangadhar1 aPawar, Dnyandeo1 aKanawade, Rajesh uhttps://library.ncl.res.in/content/fabrication-and-evaluation-spatially-resolved-fiber-optic-probe-diffuse-reflectance00734nas a2200193 4500008004100000245012800041210006900169260000900238490000700247653002300254653001000277100001600287700002300303700001800326700002000344700002400364700002100388856013100409 2024 eng d00aNormal and diabetic foot sole skin mimicking tissue phantom fulfillment for spectroscopic-based DFU diagnostics perspective0 aNormal and diabetic foot sole skin mimicking tissue phantom fulf cJUN 0 v1410aOPTICAL-PROPERTIES10aSTATE1 aKumar, Ajay1 aHattale, Gangadhar1 aHinge, Sarika1 aKulkarni, Gauri1 aLate, Dattatray, J.1 aKanawade, Rajesh uhttps://library.ncl.res.in/content/normal-and-diabetic-foot-sole-skin-mimicking-tissue-phantom-fulfillment-spectroscopic-based02461nas a2200409 4500008004100000022001400041245008800055210006900143260000900212300001600221490000700237520122100244653001601465653002501481653001701506653001501523653002601538653001901564653002201583653001301605653002101618653001601639653004201655653001201697653001301709653002401722100002001746700002401766700002201790700002001812700001601832700002101848700002201869700002101891700002101912856011801933 2024 eng d a1530-437X00aPolymeric PEI/PEG coated optical fiber fabry-perot interferometer for CO2 detection0 aPolymeric PEIPEG coated optical fiber fabryperot interferometer  cDEC  a40883-408890 v243 a

Monitoring carbon dioxide (CO2) gas is essential for numerous applications, but the detection of CO2 in miniaturized devices presents significant challenges. In this study, a polyethyleneimine/poly(ethylene glycol) (PEI/PEG) coated optical fiber Fabry-Perot interferometer (FPI) and its charge transfer process toward CO2 are investigated. Scanning electron microscopy and Fourier transform infrared spectroscopy were used to analyze the surface morphology and vibration bands of the PEI/PEG composite. The PEI/PEG composite Fabry-Perot (FP) cavity of length similar to 13 mu m is coated at the distal end of the single-mode fiber using a dip coating technique. A highly sensitive optical and low-cost FPI probe fabrication has displayed a linear sensitivity of 17.10 nm/% in the range of 0.31%-1.25% CO2 gas. The response and recovery times of the sensor are in a few tens of seconds. The enhanced performance of the sensor is primarily due to the protonation and charge transfer between CO2 gas molecules and PEI/PEG composite. Due to low-cost fabrication and high sensitivity, this FPI sensor can be used in a range of potential applications in bioprocessing, healthcare, and environmental monitoring.

10adip coating10aFresnel's reflection10aInterference10amonitoring10aOptical fiber sensors10aOptical fibers10apolymer composite10aPolymers10arefractive index10asensitivity10aSensor phenomena and characterization10asensors10aswelling10aTemperature sensors1 aPawar, Dnyandeo1 aPresti, Daniela, Lo1 aLemma, Enrico, D.1 aRainer, Alberto1 aKumar, Ajay1 aKanawade, Rajesh1 aSilvestri, Sergio1 aSchena, Emiliano1 aMassaroni, Carlo uhttps://library.ncl.res.in/content/polymeric-peipeg-coated-optical-fiber-fabry-perot-interferometer-co2-detection02443nas a2200313 4500008004100000022001400041245012100055210006900176260000800245490000600253520146100259653000801720653001701728653000801745653001501753653000801768653001501776100001801791700002001809700003001829700001701859700002201876700001401898700002201912700002101934700002101955700002401976856012902000 2025 eng d a2366-748600aBinder-free in situ interface reconstruction of NiMoO4 nanorods over Ni(OH)2 nanosheets for efficient urea oxidation0 aBinderfree in situ interface reconstruction of NiMoO4 nanorods o cDEC0 v93 a

Replacing the energy-intensive oxygen evolution reaction (OER) with the urea oxidation reaction (UOR) in electrochemical water splitting offers simultaneous green hydrogen production and urea-rich wastewater oxidation, enhancing energy efficiency and economic viability. In this study, a non-noble metal-based binder-free NiMoO4/Ni(OH)2/NF electrocatalyst is developed, featuring NiMoO4 nanorods anchored on Ni(OH)2 nanosheets. This unique morphology facilitates a highly active in situ reconstructed interface, delivering a current density of 134 mA cm-2 at 1.40 V (vs RHE) in 1 m KOH with 0.33 m urea, significantly outperforming its individual components. The catalyst demonstrates excellent stability over 50 h at 30 mA cm-2. When integrated into an anion exchange membrane urea electrolyser (13 cm2 area) with Pt@C/NF as the HER cathode, the system achieves 192 mA cm-2 at 1.60 V. The post-UOR studies confirm the presence of an amorphous NiMoO4-crystalline Ni(OH)2 interface, which plays a key role in enhancing the availability of the active sites to enhance the UOR performance. The improved electrochemical performance of the engineered catalyst can be ascribed to the in situ reconstructed amorphous-crystalline interface, optimal hydrophilicity, reduced charge transfer resistance, and the distinct morphology. This strategy offers a promising pathway for developing highly active electrocatalysts for energy conversion applications.

10aAEM10aelectrolyser10aOWS10atomography10aUOR10awastewater1 aKumar, Yogesh1 aBarik, Sidharth1 aKharabe, Geeta, Pandurang1 aTorris, Arun1 aSingh, Mayank, U.1 aMohan, S.1 aGalave, Chaitanya1 aTekawadia, Jyoti1 aKanawade, Rajesh1 aKurungot, Sreekumar uhttps://library.ncl.res.in/content/binder-free-situ-interface-reconstruction-nimoo4-nanorods-over-nioh2-nanosheets-efficient02455nas a2200241 4500008004100000022001400041245012100055210006900176260000800245300001400253490000700267520164400274100001901918700001801937700001701955700001601972700001701988700001902005700001702024700002002041700002102061856013102082 2025 eng d a2040-336400aInvestigating the visible range photoresponse of an organic single-crystal analogue of the green fluorescent protein0 aInvestigating the visible range photoresponse of an organic sing cAPR a8614-86230 v173 a

The growing demand for lightweight, flexible, semi-transparent and low-cost photodetectors (PDs) in wearable electronics and optical communication systems has prompted studies to investigate organic materials as feasible alternatives to conventional inorganic PDs. However, modern organic PDs often face responsivity, detectivity, and photoresponse speed limitations, particularly in the visible range. Here, we present the photoresponse of an organic single-crystal analogue of the green fluorescent protein (GFP) chromophore photodetector, fabricated on a silicon nitride substrate. A significant increase in photocurrent was detected upon illumination with visible wavelengths (532 nm, 630 nm, and halogen light). A remarkably consistent and repeatable photoresponse was obtained during the ON and OFF illumination cycles. The device showed the dependence of photocurrent on the applied bias voltages. The measured photocurrent, responsivity, detectivity, rise time, decay time, noise equivalent power and external quantum efficiency are studied for different wavelengths. Strikingly, the fabricated device demonstrates excellent performance in the visible region compared to several conventional organic and inorganic PDs. The observed responsivity and detectivity values for the device are 98 mA W-1 and 7.94 x 108 Jones, respectively. Furthermore, the device also exhibits rapid photoresponse dynamics with a rise time of 180 ms and a decay time of 152 ms. The excellent photodetection features indicate that the single crystal GFP could serve as a versatile broadband material for future applications in optoelectronics.

1 aVirole, Vishal1 aDabke, Niteen1 aVerma, Sahil1 aKumar, Ajay1 aPandya, Rinu1 aHusale, Sudhir1 aVanka, Kumar1 aGonnade, Rajesh1 aKanawade, Rajesh uhttps://library.ncl.res.in/content/investigating-visible-range-photoresponse-organic-single-crystal-analogue-green-fluorescent02271nas a2200361 4500008004100000022001400041245016600055210006900221260000800290300001100298490000800309520108600317653000801403653002601411653002001437653002701457653003201484653002301516100001801539700001601557700001601573700001901589700002201608700002301630700001801653700001901671700001601690700001901706700001601725700001901741700002101760856012801781 2025 eng d a0360-319900aOptimisation of metallic bismuth nanoparticle supported Pt-Bi(x%)/C hybrid electrocatalyst for cost effective and efficient hydrogen production in alkaline media0 aOptimisation of metallic bismuth nanoparticle supported PtBixC h cAUG a1506990 v1613 a

The present study employed a simple mechanochemical method followed by 24-h ultrasonication to synthesize oxide-free metallic bismuth (Bi) nanoparticles. This was further used to synthesize a Pt-Bi(x%)/C (NC-x) hybrid electrocatalyst for the hydrogen evolution reaction in alkaline media. X-ray photoelectron spectroscopy and contact angle measurements reveal, Bi modifies the electronic structure and surface morphology of the Pt/C electrocatalyst, thus enhancing reaction kinetics and active site availability. The relative three-electrode study reveals that optimised NC-20 electrocatalyst reduces the overpotentials by 10.44 % and enhances the current density by 53 % compared to commercial Pt/C. The practical applicability of the NC-20 electrocatalyst was studied with the 13 cm2 single cell anion exchange membrane electrolyser. The catalyst demonstrates promising performance where the current density of NC-20//IrO2 relatively increases by 22.6 % compared to standard Pt/ C//IrO2, and shows continuous production and stable performance when monitored for 30 h.

10aAEM10aBismuth nanoparticles10aelectrocatalyst10aFull cell electrolysis10ahydrogen evolution reaction10awater electrolysis1 aDokhe, Revati1 aUgale, Atul1 aDube, Onkar1 aVarpe, Vaibhav1 aGalave, Chaitanya1 aHattale, Gangadhar1 aKadam, Rutuja1 aVirole, Vishal1 aKumar, Ajay1 aHusale, Sudhir1 aNatu, Varun1 aShevate, Rahul1 aKanawade, Rajesh uhttps://library.ncl.res.in/content/optimisation-metallic-bismuth-nanoparticle-supported-pt-bixc-hybrid-electrocatalyst-cost02882nas a2200289 4500008004100000022001400041245015800055210006900213260000800282300001100290490000800301520188200309653002402191653003702215653001802252653002202270653001802292653002302310100001602333700001902349700002002368700002102388700001702409700001902426700002102445856012602466 2025 eng d a0030-399200aReal-time estimation of blood oxygenation parameters from human foot sole during leg elevation: a preliminary study with diffuse reflectance spectroscopy0 aRealtime estimation of blood oxygenation parameters from human f cFEB a1117060 v1813 a

This study investigated the applicability of diffuse reflectance spectroscopy (DRS) for real-time and non-invasive measurement of blood oxygenation parameters (BOPs) such as reduced hemoglobin (RHb), oxyhemoglobin (HbO(2)), and oxygen saturation (SO2) from human foot sole during leg elevation. Seventeen (17) healthy male subjects aged between 21 to 39 years were included in this study. Diffuse reflectance spectra were recorded from measurement sites namely the 5th metatarsal, ball of great joint, calcaneum, and great toe of the human foot sole w.r.t. leg elevation angles such as 0(0), 15(0), 30(0), 45(0), and 60(0), respectively. The localized BOPs were derived from the recorded spectra. In addition, blood hemodynamic parameters (BHPs) such as heart rate (HR), SO2, perfusion index (PI), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were also measured for each elevating angle. To study and assess the changes in BOPs and BHPs w.r.t. leg elevation, a One-way ANOVA test followed by a Tukey HSD post-hoc test was performed. We observed a statistically significant increase in RHb (p < 0.001) and a decrease in HbO(2) (p < 0.001) after 45 degrees of leg elevation, however, there was no statistically significant difference in SO2 (p = 0.74) and HR (p = 0.84) for each measurement site w.r.t. leg elevation, respectively. Furthermore, PI (p < 0.01), ankle SBP (p < 0.001) and DBP (p < 0.001) were decreased w.r.t. leg elevation. The obtained results are in agreement with the literature. The preliminary results suggest that DRS has the potential for real-time estimation of BOPs from the local sites of healthy human foot soles during leg elevation. Thus, it opens the possibility of DRS to monitor and evaluate the diagnosis and treatment of ischemia and edema during leg elevation of patients through BOPs measurement.

10adiabetic foot ulcer10adiffuse reflectance spectroscopy10aLeg elevation10aOxygen saturation10aOxyhemoglobin10aReduced hemoglobin1 aKumar, Ajay1 aLohchab, Viney1 aPawar, Dnyandeo1 aSomeshwar, Vimal1 aMathe, Vikas1 aHusale, Sudhir1 aKanawade, Rajesh uhttps://library.ncl.res.in/content/real-time-estimation-blood-oxygenation-parameters-human-foot-sole-during-leg-elevation02813nas a2200301 4500008004100000245016300041210006900204260000800273300001200281490000600293520178700299653002402086653002102110653002102131653002102152653002402173100002302197700001802220700001902238700001702257700001702274700001602291700001902307700001702326700001802343700002102361856012902382 2026 eng d00aPhotoluminescence decay lifetime study of hydrothermally synthesized highly porous ruthenium-silica composite for optical dissolved oxygen sensing application0 aPhotoluminescence decay lifetime study of hydrothermally synthes cJAN a937-9490 v93 a

Pore size and surface area of photoluminescence (PL)-based transition metal composites play crucial roles in facilitating oxygen diffusion, thereby enhancing the response and sensitivity of optical dissolved oxygen (DO) sensors. In this study, we successfully applied the hydrothermal method to synthesize a porous ruthenium composite embedded in a silica matrix, demonstrating its effectiveness for optical DO sensing applications. The ruthenium-silica (Ru-Si) composites were synthesized using Ru(bpy)3 2+ and tetraethyl orthosilicate (TEOS) as precursors, with reaction temperatures ranging from 120 degrees C to 200 degrees C over a fixed duration of 4 h. The structural, morphological, and compositional characterization techniques confirmed the successful synthesis and evaluated the porosity, surface features, and chemical structure of the resulting composites. The optimized Ru-Si composite exhibited the highest porosity, characterized by a specific surface area of 996.78 m2 g- 1, and exhibited the highest decay lifetime of 8.14 mu s in deionized (DI) water, compared to other composites. Importantly, we demonstrate an excellent linear response of the synthesized Ru-Si composite to DO concentrations ranging from 2.58 to 11.16 mg L-1, with a Stern-Volmer constant of 0.12. Furthermore, a density functional theory study was conducted to investigate the electronic transitions and to elucidate the oxygen quenching mechanism of the excited Ru composite with molecular oxygen. The calculated photophysical parameters of the composite show good agreement with the experimental results. Preliminary results suggest that the synthesized Ru-Si with high pore size and surface area could be an efficient and effective composite for use in DO sensing applications.

10aHydrothermal method10aopticalDO sensor10aoxygen quenching10aphotoluminescent10aruthenium composite1 aHattale, Gangadhar1 aKadam, Rutuja1 aVirole, Vishal1 aPandya, Rinu1 aPaul, Aditya1 aKumar, Ajay1 aShevate, Rahul1 aVanka, Kumar1 aSaha, Avishek1 aKanawade, Rajesh uhttps://library.ncl.res.in/content/photoluminescence-decay-lifetime-study-hydrothermally-synthesized-highly-porous-ruthenium