Wavelength Shift Research Articles

Molecular Beam Epitaxial Growth and Optical Properties of InN Nanostructures on Large Lattice-Mismatched Substrates

Narrow-gap InN is a desirable candidate for near-infrared (NIR) optical communication applications. However, the absence of lattice-matched substrates impedes the fabrication of high-quality InN. In this paper, we employed Molecular Beam Epitaxy (MBE) to grow nanostructured InN with distinct growth mechanisms. Morphological and quality analysis showed that the liquid phase epitaxial (LPE) growth of hexagonal InN nanopillar could be realized by depositing molten In layer on large lattice-mismatched sapphire substrate; nevertheless, InN nanonetworks were formed on nitrided sapphire and GaN substrates through the vapor-solid process under the same conditions. The supersaturated precipitation of InN grains from the molten In layer effectively reduced the defects caused by lattice mismatch and suppressed the introduction of non-stoichiometric metal In in the epitaxial InN. Photoluminescence and electrical characterizations demonstrated that high-carrier concentration InN prepared by vapor-solid mechanism showed much stronger band-filling effect at room temperature, which significantly shifted its PL peak to higher energy. LPE InN displayed the strongest PL intensity and the smallest wavelength shift with increasing temperature from 10 K to 300 K. These results showed enhanced optical properties of InN nanostructures prepared on large lattice mismatch substrates, which will play a crucial role in near-infrared optoelectronic devices.

Impact of Moisture Absorption on Optical Fiber Sensors: New Bragg Law Formulation for Monitoring Composite Structures

In recent decades, the aviation industry has increasingly adopted composite materials for various aircraft components, due to their high strength-to-weight ratio and durability. To ensure the safety and reliability of these structures, Health and Usage Monitoring Systems (HUMSs) based on fiber optics (FO), particularly Fiber Bragg Grating (FBG) sensors, have been developed. However, both composite materials and optical fibers are susceptible to environmental factors such as moisture, in addition to the well-known effects of mechanical stress and thermal loads. Moisture absorption can lead to the degradation of mechanical properties, posing a risk to the structural integrity of aircraft components. This research aims to quantify and monitor the impact of moisture on composite materials. A new formulation of the Bragg equation is introduced, incorporating mechanical strain, thermal expansion, and hygroscopic swelling to accurately measure Bragg wavelength variations. Experimental validation was performed using both uncoated and polyimide-coated optical fibers subjected to controlled hygrothermal conditions in a climate chamber. The results demonstrate that uncoated fibers are insensitive to humidity, whereas coated fibers exhibit measurable wavelength shifts due to moisture absorption. The proposed model effectively predicts these shifts, with errors consistently below 2.6%. This approach is crucial for improving the performance and reliability of HUMSs in monitoring composite structures, ensuring long-term safety in extreme environmental conditions.

Design of a Nested Hollow-Core Anti-Resonant Fiber Sensor for Simultaneous Measurement of Temperature and Strain

A highly sensitive sensor, which can detect the temperature and strain simultaneously, is proposed using a hollow-core anti-resonant fiber with composite nested tubes. The sensing fiber contains two kinds of nested tubes, and two different sensing mechanisms, the resonance coupling effect and the intermodal interference, are realized in the same section of a hollow-core anti-resonant fiber fully filled with ethanol. Five conjoined nested anti-resonant tubes are introduced to suppress the confinement loss of the higher-order mode LP02. One hybrid conjoined nested tube, which consists of a half-circular anti-resonant tube and a half-circular resonant tube, is introduced to induce a resonant coupling between the LP02 mode in the core and the dielectric mode in the nested resonant tubes. Numerical investigations demonstrate the shifts of the feature wavelengths of the resonance coupling effect, and the intermodal interference shows different velocities with temperature and strain, while a simultaneous measurement of temperature and strain can be realized with high sensitivities (3.36 nm/°C and −0.003 nm/με to temperature and strain, respectively). Since the sensor can be fabricated by full infiltration with liquid into the large-size core and cladding tubes of hollow-core anti-resonant fibers, and special post-processing, such as selective infiltration or coating, is notneeded. The proposed sensors based on hollow-core anti-resonant fibers with functional liquid infiltration provide a more efficient and versatile platform for the temperature and strain sensing.

Enhancing optical absorbance and accelerating rotational speed in molecular motors through oriented external electric fields

Accelerating the rotational speed of light-driven molecular motors is among the foremost concerns in molecular machine research, as this speed directly influences the performance of a motor. Controlling the motor’s rotation is crucial for practical applications, and using an oriented external electric field (OEEF) represents a feasible method to achieve this objective. We have investigated the impact of an OEEF on the optical and kinetic properties of a novel π-donor/acceptor di-substituted molecular motor, R2,3-(NH2, CHO). We employed density functional theory (DFT) and time-dependent DFT methods to analyze the electronic excitation and thermal isomerization behavior. Our results demonstrate that the absorption wavelength, absorption efficiency of the motor, and rate constant of the thermal isomerization reaction can be adjusted by applying OEEFs, which are predictable based on the dipole moment and polarizability of the molecules under consideration. In particular, we observed a shift in the absorption wavelength toward longer ranges, an enhancement in light absorption intensity, and an acceleration in the rotation rate when applying a weak positive directional external electric field to the R2,3-(NH2, CHO) motor. In summary, this theoretical study highlights the potential of OEEFs for improving the performance of molecular motors.

A novel photoluminescence theory and design rule based on solution entropy for rare earth ion doped alkaline metal silicates

This paper introduces an innovative theory for customizing photoluminescence (PL) emission wavelengths in rare earth ion (Eu2+) doped alkaline earth metals (Ca, Mg) silicates, rooted in the entropy of fusion and configurational entropy of congruent and incongruent silicates, respectively, aiming to reveal dynamic deformation of the tetrahedral SiO4 ligand within these materials. Using FactSage, we computationally calculate the fusion entropy of congruent silicates in the CaO-MgO-SiO2 system. Synthesized ternary silicates confirm our theory by highlighting correlations between lower/higher fusion entropy (for congruent) and configurational entropy (for incongruent) silicates, leading to red/blue shifts in PL emission wavelengths. In binary silicate systems, we observe an inverse correlation between PL emission wavelengths and fusion entropy of congruent silicates or pseudo-congruent silicates like MgSiO3, whose solid-liquid decomposition temperature is close to its melting point. Furthermore, the non-ideal liquid phase entropy of incongruent silicates positioned between congruent CaMgSi2O6 (Pyroxene) and congruent Ca2MgSi2O7 (Akermanite) in the MgO-CaO-SiO2 ternary phase diagram comprehensively explains diverse PL emission wavelengths. Beyond its scholarly impact, this work expands perspectives in lighting and photonic research, opening an exciting frontier in entropy-lighting research and enabling predictions of host chemical composition and tunable PL emission wavelengths, particularly relevant to LED technologies.

Oxidation of glyoxal with the Mo-oxime complex in a benzalkonium chloride interface: Raghavan and Srinivasan kinetic model

Gaining an understanding of the glucose oxidation product (glyoxal) interaction with the metal–organic complex in a biological environment is pivotal to its usage. Thus, the glyoxal (Gyx) oxidation with Mo-oxime complex (MC) is studied with the spectrophotometric method, following a pseudo-phase approach. The result highlights the inclusion of hydrolysis, ion catalysis, the neutral primary salt effect, and radical generation as the essential factors in Gyx oxidation, with the exclusion of intermediate species formation. The hydrolysis of Gxy is observed to actively engage MC without charge inhibition as charge-neutral reacting species are involved, thus, implicating neutral primary salt effect where the variation of ionic strength of the system keeps the redox rate unchanged. The involvement of charge-neutral specie at the rate controlling step encouraged electrostatic attraction when Mg2+ ion additive is incorporated into the system, leading to ion catalysis. The generation of free radical from Gxy aids the emergence of formic acid. The zero intercept of Michealis-Menten type plot and the non-appreciable shift in the maximum absorption wavelength of the reaction system and MC rule-out the presence of intermediate species. The contribution of thermodynamic enthalpy is instrumental in the redox process, leading to the formic acid product. The inclusion of benzalkonium chloride (BZC) hastens the Gxy oxidation, which is supported by Raghavan and Srinivasan’s model.

Multifunctional III-nitride optoelectronic system on a tiny chip

Multi-quantum well (MQW) diodes exhibit simultaneous emission and detection, allowing them to serve as multifunctional devices, including light emitters, receivers, energy transmitters, and information transmitters. Leveraging this capability, we designed a Multifunctional Energy Transfer Information System (METIS) that integrates contactless control, energy harvesting, and information transfer. At the core of this system, the multifunctional energy communication chip operates effectively across a broad range of extreme temperatures and in various solution environments. As the ambient temperature varies from −60 to 120 °C, the peak emission wavelength shifts from 465 to 476 nm, and even with further temperature changes from −70 to 150 °C, the communication function remains stable. Encapsulated for durability, METIS functions reliably in extreme conditions such as ice, water, salt solutions, and other light-transmitting fluids without needing external circuitry. Additionally, we demonstrate passive control of analog switches via MQW diodes. The MQW diodes also enable contactless energy and optical information transfer, ensuring stable and controllable information reconstruction at the receiving end. This approach offers an innovative solution for energy and information transmission in extreme environments.

Simulating a Temperature, Stress And Strain FBG Sensor for Troposphere Layer

In this study, a simulation and design for a temperature (T) sensor are investigated by using the fiber Bragg gratings (FBG). The study investigated and characterized the FBG regarding maximum reflectivity, bandwidth, and the influence of applied strain on the shift in Bragg wavelength (λB). This is via measuring sensitivity of wavelength shift under strain in an optical sensing system. The response of FBG sensors was also investigated and optimized. Uniform FBG spectra and theoretical comparisons were conducted considering the influence of several selected external strain/stress (S) values: 101.325, 89.874, 79.495, 70.108, 61.640, 54.019, 47.181, 41.060, 35.599, 30.742, 26.436. The Optisystem 16 software is analyzing these two types of effects. The measured parameters, such as sensitivity, were determined by using a white light source. The light source operating wavelength was 1550 nm. This is to design the sensor especially for troposphere that have high sensitivity (1279.7472 pm/oC. The sensitivity obtained exhibited varying values between 1279.7472 and 1239.7551 for strain. The peak sensitivity observed is associated with 550 nm of wavelength. Result for measured sensitivity against S by the FBG sensor was 15.5087 pm/oC with sensor length 20 mm. While it was found equals 15.5131 pm/oC with sensor length 10 mm. T sensing is simulated for selected values (15, 8.5, 2, -4.5, -11, -17.5, -24, -30.5, -37, -43.5, -50 oC). Resulted sensitivity was found to fluctuate fitting sine, Long Normal, and Boltzmann functions, indicating large sensitivity for the simulated sensor responses.

Enhanced cathodic electrodes from V2O5 nanorods: Pioneering organic dye degradation and optimized catalysis for sustainable supercapattery devices

Encapsulating the essence of multifunctionality, the synthesized Vanadium Pentoxide (V2O5) nanorods (NRs) are adaptable innovators of visible-light photocatalytic degradation and sustainable supercapattery device fabrication. Meanwhile, the physicochemical properties are investigated by precise instruments. The V2O5 NRs demonstrate improved photocatalytic performance over a 100-min duration, effectively catalyzing the methylene blue (MB) degradation with a remarkable degradation percentage of 98.37 % (25 mg catalysis) and shows a lower wavelength shift due to MB molecular braking. In a groundbreaking twist, this work utilises tainted V2O5 NRs, ingeniously repurposing them to energy storage tenacities. In addition, the electrochemical assessment of tainted V2O5 NRs demonstrated subtle changes after MB degradation, increasing the specific capacity (Cs) value from 794 to 933C.g−1 due to developing reduced particle agglomeration. Moreover, the better Cs value of tainted V2O5 NRs reached 95.02 % after 500 cycles (5 A.g−1). The fabricated asymmetric supercapattery (ASC) device demonstrates superior ion diffusion processes, as evidenced by Dunn's method calculations, particularly at a scan rate of 5 mV.s−1. Additionally, the assembled device underscored their unique positioning between battery and capacitor materials, distinctly supported by a “b” value of 0.8 and superior capacity retentivity. They reached a superior power (P = 191.75 W.kg−1) with energy (E = 50 Wh.kg−1) and better cyclic stability, maintaining their performance over 4000 cycles at 5 A. g−1 (91.3 %). Furthermore, under exposure to the light of a yellow light emitting diode (LED) for 30 s, the real-time consequences of after cyclic stability material of tainted V2O5 NRs are investigated, providing meaningful insights into their performance dynamics.

Optical fiber membrane-based Fabry–Perot tactile force sensing platform powered by LED ambient lighting

This study introduces an optical fiber tactile force sensing platform powered by ambient LED lighting. Based on the interaction between a multimode optical fiber and a micro-polymer membrane, it is possible to excite an Extrinsic Fabry-Perot Interferometer (EFPI); this EFPI is pumped by collected incident light from the ambient LED lighting environment; here, a Fresnel lens and multimode fiber collect this light. The collector system maintains suitable light intensity even during 360° rotation. When transversal loads between 0 to 1 N are applied over the membrane, the tactile force sensor shows a wavelength shift towards shorter wavelengths; consequently, a 6.5 nm/N sensitivity and resolution of 0.15 N are obtained. Moreover, the phase analysis of the Fourier spectrum addresses intensity variations during rotation, revealing a sensitivity of 3 rad/N. The sensor offers stability, minimal hysteresis, minimal temperature modulation, and suitable time response across four sensing areas. Moreover, the statistical analysis and tactile force sensor performance ensure reliable tactile measurement with a null probability of overlap upon force application. It is crucial to note that this tactile force sensor provides a genuinely low-cost implementation due to the utilization of ambient LED lighting as the light source. This aspect represents an exciting advancement in fiber sensing technology.

Calibration and Validation of NOAA-21 Ozone Mapping and Profiler Suite (OMPS) Nadir Mapper Sensor Data Record Data

The Ozone Mapping and Profiler Suites (OMPS) Nadir Mapper (NM) is a grating spectrometer within the OMPS nadir instruments onboard the SNPP, NOAA-20, and NOAA-21 satellites. It is designed to measure Earth radiance and solar irradiance spectra in wavelengths from 300 nm to 380 nm for operational retrievals of the nadir total column ozone. This study presents calibration and validation analysis results for the NOAA-21 OMPS NM SDR data to meet the JPSS scientific requirements. The NOAA-21 OMPS SDR calibration derives updates of several previous OMPS algorithms, including the dark current correction algorithm, one-time wavelength registration from ground to on-orbit, daily intra-orbit wavelength shift correction, and stray light correction. Additionally, this study derives an empirical scale factor to remove 2.2% of systematic biases in solar flux data, which were caused by pre-launch solar calibration errors of the OMPS nadir instruments. The validation of the NOAA-21 OMPS SDR data is conducted using various methods. For example, the 32-day average method and radiative transfer model are employed to estimate inter-sensor radiometric calibration differences from either the SNPP or NOAA-20 data. The quality of the NOAA-21 OMPS NM SDR data is largely consistent with that of the SNPP and NOAA-20 OMPS data, with differences generally within ±2%. This meets the scientific requirements, except for some deviations mainly in the dichroic range between 300 nm and 303 nm. The deep convective cloud target approach is used to monitor the stability of NOAA-21 OMPS reflectance above 330 nm, showing a variation of 0.5% over the observed period. Data from the NOAA-21 VIIRS M1 band are used to estimate OMPS NM data geolocation errors, revealing that along-track errors can reach up to 3 km, while cross-track errors are generally within ±1 km.

Self-Assembly of Colloidal Dumbbell Isomers and Plasmonic Properties for Optical Metamaterials.

In this study, we explore the self-assembly of various colloidal symmetric dumbbell (DB) isomers, including dipole Janus, cis-Janus, trans-Janus, apolar-inward and polar-inward perpendicular Janus, and alternating perpendicular Janus DBs. Using dissipative particle dynamics (DPD) simulations under conditions mimicking experimental setups, we investigate cluster formation driven by emulsion droplet evaporation. Our findings reveal a diverse set of cluster structures, which are in good agreement with experimental and simulation results reported in the literature while also predicting the formation of novel cluster configurations. These structures, characterized by well-defined and predictable patterns, are potentially applicable to creating colloidal molecules and crystals. Furthermore, we examine the dynamics of cluster formation to gain insight into the mechanisms guiding the self-assembly of these diverse colloidal DBs. The study highlights the impact of particle isomerism on the resulting assembly structures. We further select a set of typical nanoclusters obtained, including a tetrahedral cluster, which is the simplest, to study its plasmonic properties. Our findings indicate that increasing the nanoparticle (NP) radius or decreasing the gap between NPs leads to a red shift in the plasmonic resonance wavelength and enhances the resonance strength. We identify critical parameter regions where the electric-dipole and magnetic-dipole resonances can be engineered to achieve negative dielectric permittivity and magnetic permeability, which are essential for developing negative-index metamaterials.

Full-range displacement sensor with dual FBGs combined cantilever beam based on magnetic grating

We propose a full-range displacement sensor system based on double fiber Bragg gratings (FBGs) with a cantilever beam. This sensor adopts a magnetic scale as a unique transmission mechanism. By combining a simple and low-cost cantilever beam structure makes the sensing probe very easy to realize. The optimal magnetic gap was explored through multiple sets of numerical simulations. The experiment proved the sine relationship between the center wavelength shifts of FBGs and the linear displacement, proving the feasibility of this method. Results indicate that the amplitude of the tensile compression load of FBGs are 169.76 με and 296.12 με. The fitting linearity based on sinusoidal function at an air gap of 3.5 mm is 0.9663 and 0.9566. The direction of motion can be determined by the phase difference between two FBGs. Moreover, the difference of double FBGs can realize the effect of temperature compensation. Thus, this sensor can achieve non-contact, temperature-independent, and full-range measurements. It can also be exploited to measure other parameters such as angular velocity, acceleration, and magnetic field strength.

Mechanochromic Organic Micro-Laser.

This work presents the first demonstration of a mechanochromic organic micro-laser, which exhibits remarkable wide range pressure sensing characteristics. The gain material, pinacolato boronate ester functionalized anthanthrene (AnBPin), is designed by incorporating mechanofluorochromic (MFC) properties into organic laser dye. The AnBPin exhibits a reversible transition between green and orange fluorescence upon grinding annealing and recrystallization cycle, and its micro-crystal exhibits typical organic micro-laser behaviors. Applying localized mechanical pressure as low as 0.1 MPa inhibits micro-laser behavior at the given spot. In contrast, under 1 to 2 GPa hydrostatic pressure, the organic laser maintains narrow emission while showing a pressure-dependent shift in emission wavelength. By combining theory and experimentation, we attribute the unusual pressure-correlated emission spectroscopy to the unique interleaved locked crystal structure. Understanding the mechanochromic laser behavior in AnBPin micro-crystals under an unprecedented pressure range significantly expands the family of organic micro-lasers and provides a new route for wide-range photonic pressure detection.

Magnetic Field Sensor Using the Magnetic Fluid-Encapsulated Long-Period Fiber Grating Inscribed in the Thin-Cladding Fiber

Optical magnetic field current sensors could overcome the shortcomings of traditional sensors based on electrical principles, such as large volume, insufficient sensitivity, and limitations of working environment, which can be applied to medical, military, and other fields with higher sensing requirements. We demonstrated experimentally the inscription of the long-period fiber gratings (LPFGs) in the thin-cladding fiber (TCF). The magnetic field current sensor is fabricated by encapsulating the TCF–LPFG with magnetic fluid (MF) nanoparticles. The principle of the sensor is based on the refractive index tunability of the MF with the magnetic field (current). The measurement of the external magnetic field (current) can be obtained by detecting the wavelength shift of the coated TCF–LPFG, which changes with the applied magnetic field. In the intensity range of 0 ∼ 11 mT, the experimental sensitivity of magnetic field measurement is up to −0.31 nm/mT. The proposed magnetic field current sensor has potential applications in practical measurement of magnetic field.

Raman-induced wavelength shift in chalcogenide microstructure fiber: temperature sensing and machine learning analysis

Raman-induced wavelength shift in chalcogenide microstructure fiber: temperature sensing and machine learning analysis

Highly sensitive colorimetric method for the detection of organophosphorus pesticides based on H2O2 etching of silver-coated gold nanostars

The residues of organophosphorus pesticides in agricultural production and soil constitute a significant threat to both human health and ecosystems, underscoring the critical importance of developing effective detection methods for these pesticides. Here, we introduce an innovative method for detecting trichlorfon that integrates hydrogen peroxide (H2O2)-induced etching of silver-coated gold nanostars (AuNS@Ag) with an enzymatic reaction cascade. By precisely controlling the thickness of the silver layer and the morphology of the gold nanoparticle core, we enhance the sensitivity of the H2O2 etching process. In this detection system, acetylcholinesterase (AChE) catalyzes the hydrolysis of acetylcholine chloride (ACh) into choline, which is then oxidized by choline oxidase (ChOx) to produce H2O2. The generated H2O2 subsequently etches the silver layer of AuNS@Ag, leading to a pronounced red-shift in the localized surface plasmon resonance (LSPR) wavelength, from 590 nm to 735 nm. However, the presence of trichlorfon inhibits the activity of AChE, resulting in a reduced production of H2O2 and a subsequent attenuation of the LSPR wavelength shift. Under optimized experimental conditions, this method enables the linear detection of trichlorfon within a concentration range of 0.1–5.0 μg mL−1 and has been successfully applied to detect trichlorfon in cabbage and tap water samples, showcasing its promising potential in food safety and environmental monitoring.

Highly sensitive fiber vector magnetic field sensor based on an open-cavity Mach-Zehnder interferometer filled with magnetic fluid

In this paper, we proposed and demonstrated a highly sensitive fiber vector magnetic field sensor utilizing an open-cavity Mach-Zehnder interferometer (MZI) filled with magnetic fluid. The MZI sensor was fabricated using large-offset splicing technique to form an open cavity, facilitating the easy introduction of magnetic fluid samples into the open cavity. The MZI sensor was then encapsulated in a glass capillary containing diluted magnetic fluid. As the applied magnetic field varies, the refractive index of the magnetic fluid undergoes a corresponding change, subsequently inducing a shift in the transmission spectrum of the MZI. By monitoring the wavelength shift of the transmission spectrum, we can accurately detect the intensity of the magnetic field. The proposed sensor can achieve vector magnetic field measurement because of the axially asymmetric open-cavity MZI. The maximum sensitivity to magnetic field direction is 0.260 nm/°. Notably, the proposed sensor achieves an ultrahigh sensitivity, reaching an value of −17.306 nm/mT within the range of 4 mT to 7 mT. In addition, a temperature sensitivity of 2.236 nm/℃ is obtained within the temperature range of 30 ℃ to 65 ℃. Given its advantages, including high sensitivity, compact size and low cost, our MZI sensor holds immense potential for diverse applications in magnetic field measurement.

Simultaneous sensing of axial strain and temperature based on a sensitivity-selectable all-fiber Lyot-like filter

In this paper, an all-fiber Lyot-like filter with tunable free spectral range (FSR) and selectable sensitivity is proposed and experimentally demonstrated for simultaneous sensing of axial strain and temperature. Compared to the traditional fiber-based Lyot filter, the Lyot-like filter has an additional single-mode fiber (SMF) based polarization controller (PC), which is placed between two sections of polarization-maintaining fiber (PMF). In our experiment, the tunable FSR is achieved by adjusting the PC at a special angle, and a small FSR value of 6.58 nm and a large FSR value of 18.49 nm are obtained, respectively. Moreover, the experimental results show that the small FSR has low axial strain and temperature sensitivity, while that of the large FSR is high. By detecting the wavelength shifts of the filter spectra dip points, the simultaneous sensing of axial strain and temperature can be realized easily using a dual-parameter matrix. The proposed Lyot-like filter has the advantages of tunable FSR, selectable sensitivity, and simultaneous measurement of temperature and axial strain, which shows potential sensing applications in aerospace, chemical production, and bridge condition monitoring.

Effect of Acetonitrile on the Conformation of Bovine Serum Albumin.

The use of organic solvents in drug delivery systems (DDSs) either to produce albumin nanoparticles or to manipulate the binding of target molecules to albumin, a promising nanocarrier material, presents challenges due to the conformational changes induced in the protein. In this study, we investigated the alterations in the conformation of bovine serum albumin (BSA) caused by acetonitrile (ACN) in aqueous solution by using a combination of spectroscopic analysis and molecular dynamics (MD) simulations. Ultraviolet (UV) absorption, fluorescence, and infrared (IR) absorption spectroscopy were used to analyze the BSA conformation in the solutions containing 0-60 vol % ACN. Additionally, MD simulations were conducted to elucidate the interactions between BSA and solvent components, focusing on the structural changes in the hydrophobic pocket with Trp residues of the albumin. Increasing the ACN concentration leads to significant changes in the BSA conformation, as evidenced by shifts in UV fluorescence wavelength, decreased intensity, and alterations in IR absorption bands. Furthermore, the formation of protein aggregates was observed at high ACN concentration (30 vol % ACN), shown by increased hydrodynamic diameter distribution. MD simulations further demonstrate that the presence of ACN molecules near the hydrophobic pocket with the Trp-213 residue increases the fluctuations in the positions of amino acids observed near the hydrophobic pocket with Trp-213. Moreover, the intrusion of water molecules into the hydrophobic pocket under 60% ACN conditions with highly decreased solvent polarity was correlated with the changes in the BSA secondary structure. These findings enhance our understanding of how solvent polarity affects the albumin conformation, which is crucial for optimizing albumin-based DDS applications.