Fiber Structure Research Articles

Elucidating the mechanism of inulin-induced improvement in the structural and functional properties of High-moisture extruded products

High-moisture extrusion (HME) has increasingly garnered attention in the production of plant-based meat analogs. Nevertheless, the disorganized structural properties and poor functional characteristics of HME extrudates pose significant challenges to the advancement of plant-based alternatives in the food industry. The coextrusion of proteins and polysaccharides has emerged as an effective strategy to improve the sensory qualities of HME meat analogs. Herein, we investigated the effects of the type and addition of inulin on the structural and functional properties of HME extrudates comprising soy protein isolate, soy protein concentrate, and wheat protein. The results indicated that inulin facilitated the conversion of 7S to 11S globulin and induced a transformation from a β-turn angle to a β-folded protein structure, promoting lamellar structure formation and enhancing the overall stability of the protein matrix. Optimal results were achieved with the addition of 6% long-chain and short-chain inulin. In terms of functional characteristics, the incorporation of short-chain inulin resulted in a superior fiber structure and protein digestibility, whereas long-chain inulin enhanced the water-holding capacity, rehydration rate, and thermal stability. Additionally, intermolecular interaction analysis revealed that these inulin-induced improvements in the quality of HME extrudates are primarily attributed to the strengthening of disulfide bonds and hydrogen bonds. These findings offer crucial insights for advancing the quality of plant-based meat analogs, providing valuable directions for future product development in the food industry.

Advances in Plasmonic Photonic Crystal Fiber Biosensors: Exploring Innovative Materials for Bioimaging and Environmental Monitoring

AbstractThis review paper comprehensively analyzes recent advancements in optical fiber‐based biosensors, focusing on conventional fiber and photonic crystal structures. This paper overviews the significant applications of optical fiber biosensors, including bioimaging, quality analysis, food safety, and field environment monitoring, setting the stage for subsequent discussions. The primary objective of the review is to systematically evaluate recent literature concerning optical fiber‐based biosensors, emphasizing their sensitivities and resolutions. The second section explores integrating plasmonic materials such as graphene, TDMC, germanium, black phosphorus, and silicon within optical fiber biosensors, elucidating their roles in enhancing sensitivity and resolution in biosensing applications. A detailed examination of photonic crystal fibers (PCF) follows, categorizing them into internally and externally metal film‐coated biosensors, highlighting their distinct advantages and limitations. Comparative analyses in two tables delineate the performance and sensitivity of optical fiber‐based biosensors, mainly focusing on different coating strategies. The final section of the review discusses emerging trends and applications in optical fiber biosensing technologies, underscoring their potential to transform biomedical and environmental monitoring fields. By synthesizing recent developments and challenges, this review aims to offer researchers and practitioners a comprehensive understanding of optical fiber‐based biosensors, facilitating informed decision‐making and driving further advancements in the field.

Pseudo‐ductility behavior of carbon/glass hybrid composites with unidirectionally arrayed chopped strands: Experimental and numerical research

AbstractAlthough lightweight fiber‐reinforced polymer (FRP) composites are widely used in various engineering fields due to their high specific strength and modulus, the mutual exclusion of strength and toughness is one of the bottlenecks in the field of FRP design because of the inherent brittleness of fiber themselves. In this research, discontinuous fiber structures with vertical and bi‐angled slits are introduced into the thin‐ply carbon fiber prepreg. The fracture energy and delamination degree of the center carbon fiber layer could be controlled by adjusting the structural parameters to design the pseudo‐ductility of carbon/glass (C/G) hybrid laminates and obtain the higher pseudo‐yield stress. The hybrid specimens with 20 mm slits exhibit obvious pseudo‐ductility, and the pseudo‐ductility strain increases as the C/G ratio increases, while the plateau stress decreases. The larger slit distance provides sufficient propagation space for the delamination damage, which dissipates tensile energy and results in a smoother plateau area of the stress–strain curve. The stress–strain curve of the specimen with a smaller slit exhibits a noticeable rapid load decrease caused by the transient propagation of delamination damage. The peak stress of hybrid laminate with bi‐angled slits shows the highest pseudo‐yield stress. The present finite element model successfully analyzed the pseudo‐ductile damage propagation of C/G hybrid laminates with vertical slits, and the results are in good agreement with the experiments.Highlights Revealed the pseudo‐ductility behavior of carbon/glass hybrid composites. The pseudo‐ductility of carbon/glass hybrid composites is controllable. The pseudo‐ductility strain increases with the increase of C/G ratio.

Nested hollow-core anti-resonant fiber with elliptical cladding for 2 µm laser transmission

In this work, a nested hollow-core anti-resonant fiber (HC-ARF) with an elliptical cladding for high-power lasers for 2 µm laser transmission was proposed and theoretically investigated. The dual-layer elliptical tubes nested within the fiber enable the low-loss single-mode transmission. The finite element method (FEM) was employed to analyze and optimize the structure of fiber, with a total loss of less than 5 × 10−4 dB/m across the wavelength range of 1920nm to 2040nm. An extremely low loss of 1.22 × 10−5 dB/m at 1948nm was realized. A high-order mode extinction ratio (HOMER) exceeding 3 × 104 was maintained across a significant bandwidth and a size tolerance ratio under 15%. Furthermore, a low loss of 5 × 10−5 dB/m at 1948nm with a bending radius over 15 cm was obtained, indicating high bending resistance. It was demonstrated that the proposed fiber has exceptional transmission performance for 2 µm laser transmission.

Non-transverse electromagnetic fields in micro- and nano-fibers

We present an analytical and numerical study of electromagnetic modes in micro- and nano-fibers (MNFs) where the electric and magnetic fields of the modes are not necessarily orthogonal to each other. We first investigate these modes for different fiber structures including circular- and rectangular-core fibers as well as photonic crystal fibers. We then discuss two specific applications of these modes: (1) generation of hypothetical axions that are coupled to the electromagnetic fields through the dot product of electric and magnetic fields of a mode, E→⋅B→, and (2) a new type of optical trap (optical tweezers) for chiral atoms with magneto-electric cross coupling, where the confining potential again is proportional to E→⋅B→.

Effect of temperature gradient on the chemical structure and physical morphology of polyacrylonitrile fibers during thermal stabilization process

The thermal stabilization process is a crucial stage for microstructure transformation and quality of carbon fibers, which is determined by the stabilization temperature gradient. In this work, the effect of the temperature gradient on the evolution of both chemical structures and physical morphology of polyacrylonitrile (PAN) fibers at multistage of thermal stabilization process was investigated. Combined with functional groups, oxygen element content, and aromatization index, increasing temperature reasonably shifted oxidation and cyclization reaction into early stage and the corresponding samples possessed relatively large degree of cyclization. It was worth noting that high stabilization temperature gradient could accelerate the formation of the conjugated structures at early stage and facilitate the cyclization reaction in the stabilized fibers. As for morphologies, there were aligned microfibrils and transvers lamellae in stabilized fibers. Their radial structure difference increased firstly and then decreased in the later stage. The tensile strength and tensile modulus decreased during the thermal stabilization process. Moreover, increasing temperature resulted in reduction of tensile strength and tensile modulus, which was mainly resulted by the high degree of cyclization instead of structural defects. These results guide the design and optimization of temperature program and adjusting the processing parameters for all commercially PAN fibers without any additional conditions.

Broadband flat supercontinuum generated by chalcogenide double-clad step-index fiber with special dispersion

To achave a broader supercontinuum in the mid-infrared band, a chalcogenide double-clad step-index fiber is proposed. Comprising As2Se3, AsSe2, and As2S5 glass, this fiber effectively confines light within the core, minimizing fiber dispersion fluctuations. By iteratively adjusting the dispersion curve of the fiber, enhancement of the supercontinuum spectrum generation is possible. Spectral broadening primarily results from four-wave mixing and self-phase modulation. Raman scattering within the pulse generates unstable higher-order solitons, which, upon breakup, contribute to spectrum broadening. This study explores the effects of pulse laser parameters and fiber length on supercontinuum generation, obtains regular cognition and offers theoretical analyses of the results. Through optimization of parameters, a mid-infrared supercontinuum with an 11 μm width is achieved. These findings underscore the potential of chalcogenide double-clad step-index fiber for generating a mid-infrared supercontinuum light source. The designed fiber structure should be helpful in supercontinuum sources, bio-molecule sensing, and spectroscopy.

Full micro-nanofiber aerogel with three-dimensional fluffy network structure for rapid liquid absorption and uniform liquid retention in diapers

Diapers are essential for infants and patients with urinary incontinence. The super-absorbent polymer (SAP) in the core layer of diapers suffers from slow liquid absorption, fault formation, and reverse osmosis. Therefore, it is desirable to construct a core layer that can integrate rapid liquid absorption, uniform retention, and anti-seepage qualities. In this study, a diaper core layer and a three-dimensional fluffy network structure with a wetting gradient was constructed via one-step solution blow spinning (SBS). By regulating the content of the glutaraldehyde (GA) cross-linking agent, absorbent and insoluble fibers could be obtained. The ratio of super-absorbent fibers (SAF) to PAN-PVP micro-/nano fibers in the three-layer fiber structure and the gram weight of the core layer were adjusted. A wetting gradient was established when the weight of the adjusted gradient core layer was 2/3 that of the commercial core layer. The amount of reverse osmosis was reduced by 0.25 g, and the liquid absorption and retention were 30 times and 28.5 times, respectively, two and 3.5 times higher than those of commercial diapers. The SAF prepared by SBS could improve the core layer's liquid absorption rate, retention ratio, and comfort. The fibers are applicable in diapers, sanitary napkins, and other disposable products.

Fenton-Based Treatment of Flax Biomass for Modification of Its Fiber Structure and Physicochemical Properties

The availability of a sustainable technique for degumming lignocellulose fibers is a challenge for the fiber processing industry. Removal of non-cellulosic content from lignocellulose fibers is essential for improving their mechanical and chemical properties, which makes the fibers more suitable for various applications. Herein, a catalytic Fenton-based oxidation process was employed to isolate microcellulose fibers from raw flax fibers. Various complementary methods such as FT-IR/NMR spectroscopy and TGA were used to obtain insight into the thermal behavior of the treated fibers. The morphology of the fibers was studied using Scanning Electron Microscopy (SEM), whereas the surface chemical properties of the fibers was evaluated by a dye-based adsorption method, along with a potentiometric point-of-zero-charge method. To obtain fibers with suitable properties, such as uniform fiber diameter, several Fenton reaction parameters were optimized: pH (7), reaction time (15 h), iron sulfate (2 wt.%), and hydrogen peroxide (10 wt.%). The results indicate that, under the specified conditions, the average diameter of the raw fibers (12.3 ± 0.5 µm) was reduced by 58%, resulting in an average diameter of 5.2 ± 0.3 µm for the treated fibers. We demonstrate that the treated fibers had a lower dye adsorption capacity for methylene blue, consistent with the smoother surface features of the treated fibers over the raw flax fibers. Overall, this study contributes to utilization of the Fenton reaction an efficient oxidation technique for the production of lignocellulose fibers with improved physicochemical properties, such as reduced fiber diameter distribution, in contrast with traditional alkali-based chemical treatment.

Post-COVID asthenia, sarcopenia and muscle weakness among geriatric patients

Sarcopenia, asthenia, and motor activity restriction are common among geriatric patients in the post-COVID period. The SARS-CoV-2 virus triggers a cytokine storm in the human body and induces a direct viral effect on skeletal muscles. Manifestations of post-acute sequelae of COVID-19 (PASC) can include organ and system dysfunction, asthenia, muscle weakness, dyspnea, chest pain, cognitive impairment, depression, anxiety, and sleep disorders. Hypoxemia, comorbidity, and prolonged inactivity contribute to changes in the structure and functionality of the muscular fibers. One of the recent studies is ALMI-index, which indicates that a decrease in muscle mass of the upper and lower extremities may cause functional limitations in patients with long-COVID conditions. Rehabilitation of patients with post-COVID syndrome involves daily exercise with weights, considering load tolerance; mandatory medication; and nutritional and psychological support.

Laboratory investigation on static and dynamic properties, durability, and microscopic structure of Nano-SiO2 and polypropylene fiber cemented soil under coupled seawater corrosion and cyclic loading

Cemented soils in coastal harbors are susceptible to adverse factors such as seawater corrosion and cyclic dynamic loading, which may consequently reduce their stability and durability. In recent years, Nano-SiO2(NS) has been widely used to enhance the mechanical properties of cemented soil. However, this enhancement may potentially lead to a reduction in ductility. Conversely, polypropylene fibers (PP) have attracted widespread attention for their potential to enhance the ductility of cemented soils, but their ability to improve the strength of cemented soils is limited. To address these issues, this study focused on utilizing five different nano-dosages combined with four different fiber dosages to enhance cemented soils. These enhanced soils were then subjected to curing periods of 7, 28, and 60 days in seawater environments. The study employed various tests including unconfined compressive strength tests (UCS), uniaxial cyclic loading tests, scanning electron microscopy tests (SEM), X-ray diffraction (XRD), and nuclear magnetic resonance (NMR) to investigate the potential impacts of these additives on durability, strength, corrosion resistance, and microstructure evolution. The results of the study indicate that seawater corrosion and cyclic loading contribute to a reduction in the stability of cemented soils. However, the addition of NS and PP effectively enhances the compressive strength and durability of these soils. The optimal combination ratio is achieved when the dosages of NS and PP are 3.6 % and 0.8 %, respectively. In this case, the growth rate of unconfined compressive strength of cemented soils surpasses the sum of each individual dosage, increasing by 137.7 %, 245.6 %, and 235.3 % after 7, 28, and 60 days of curing, respectively. Furthermore, the growth rate of PP on the compressive strength of cemented soils remains largely unaffected by seawater corrosion. The optimal composite dosage of cemented soils effectively mitigates the increase in porosity caused by seawater corrosion. C-S-H enhances the mechanical interlocking between hydration products and PP by encapsulating PP, reducing energy transfer losses in cemented soils, and increasing their dynamic modulus. The volcanic ash reaction and nucleation effect of NS further enhance this effect, and their combined use significantly improves the seawater corrosion resistance of cemented soils.

Bridging dielectric-magnetic synergistic units with MOFs on fibers structure for high-efficient microwave absorption at low filler loading

Metal-organic framework (MOF) capable of magnetic-dielectric synergy loss mechanisms shine in the field of electromagnetic wave (EMW) absorption, whereas their high filler loading in the matrix remains a challenge and limit their practical application. Here, we mono-disperse bimetallic CoZn-MOF on conductive carbon nanofibers precursor via electrospinning technique and a following heat-treatment was employed to construct a Co–ZnO@NC carbon nanofiber (CNF) composites. The Co–ZnO particles with a size of 2 μm are evenly distributed within the carbon fibers, forming a unique structure resembling a “pearl necklace”. The introduction of one-dimension (1D) CNF can prolong the electron transport path and effectively reduces the percolation threshold of the composites. The composites are endowed with abundant heterogeneous interfaces, excellent magnetic-dielectric synergy and improved impedance matching, benefiting from which the obtained Co–ZnO@NC CNF composites demonstrate a maximum reflection loss (RLmin) of −54.5 dB at a thickness of 2.3 mm and an effective absorption bandwidth (EAB) of 8.12 GHz at a filler loading of merely 10 %. This study provides a feasible strategy for the design of MOF-derived absorbers with enhanced microwave absorption capacity at low filler loading.

Microstructure evolution and mechanical properties of Cu–9Ni–6Sn alloy during continuous cold deformation process

A Cu–9Ni–6Sn alloy bar with pronounced axial columnar grains and a diameter of 10.5 mm was fabricated by using directional solidification technology, which was directly cold-drawn into a superfine alloy wire with a diameter of 40 μm without intermediate annealing. The strength and microstructure evolutions of the Cu–9Ni–6Sn alloy during the cold drawing were studied. The results indicate that twinning is more likely to occur in fiber structures ranging from 60 to 120 nm. A dual-fiber structure consisting of <111> and <100> orientations formed after cold-drawing. Unexpectedly, a large number of deformation twins were discovered within the <111> fibrous texture and later transformed into detwinning structures, disrupting the axial fibrous texture. The generation of deformation twinning primarily results from Ni and Sn elements disrupting crystal symmetry and reducing stacking fault energy of the alloy and the formation of <111> texture. The combined effects of detwinning structures and dislocation wall induced work-softening of the alloy, enabling high-strain processing and ultimately yielding nanocrystalline grains, i.e., the Cu–9Ni–6Sn alloy underwent cold drawing with a high train of 11.23 and obtained an average grain size of ∼38 nm, which exhibited a tensile strength of 1453 MPa.

A handheld rapid detector of soil total nitrogen based on phase-locked amplification technology

Soil total nitrogen (STN) serves as a critical indicator for agricultural productivity. Rapid STN detection is crucial for nutrient monitoring in farmland and for guiding precision fertilization. Traditional near-infrared spectroscopy-based STN detectors necessitate darkrooms or subterranean settings to negate ambient light interference, restricting their practical use. This study develops a handheld rapid STN detector employing phase-locked amplification technology to address this issue. The device comprises optical, circuit, and control units. The optical unit features a ring-shaped split fiber structure to mitigate soil surface irregularities’ effects on the signal, with a central InGaAs photodiode for signal reception. Eight wavelengths (970 nm, 1050 nm, 1085 nm, 1200 nm, 1300 nm, 1450 nm, 1550 nm, and 1600 nm) are selected for the light sources through an information theory optimized genetic algorithm. The circuit unit employs direct digital synthesis and operational amplifiers for light signal generation and modulation. Reflected soil light signals are demodulated using an InGaAs photodiode and a phase-locked amplifier, effectively filtering ambient light noise. The control unit integrates an STM32F103C8T6 microcontroller and a Raspberry Pi 4B. The STM32 microcontroller manages signal generation, channel selection, frequency control, A/D conversion, and display, while the Raspberry Pi handles data processing, uploading, and transmission. A BP neural network model optimized by genetic algorithms is embedded for real-time STN data acquisition. Cloud-based data storage and visualization are facilitated through the Alibaba Cloud IoT platform. Performance testing reveals the device’s stability and interference resistance, with a standard deviation of electrical signal under varying light conditions below 3 mV. Compared to commercial spectrometers, the correlation coefficient (r) for reflectance data at eight wavebands exceeds 0.9. Accuracy testing shows an R2 above 0.8 and an RMSE of 0.30 g/kg when comparing detector-obtained STN values with standard chemical methods. These results demonstrate the detector’s efficacy in ambient light isolation, stability, and accuracy in agricultural settings, offering technical support for variable fertilization in precision farming.

Recent Advances in Fabrication and Applications of Yttrium Aluminum Garnet-Based Optical Fiber: A Review.

Yttrium aluminum garnet (YAG)-based optical fiber is one of the research hotspots in the field of fiber lasers due to its combined advantages of a wide doping range of rare earth ions and the high mechanical strength of YAG material, as well as the flexibility and small size of the fiber structure. YAG-based optical fibers and related laser devices can be used in communication, sensing, medicine, etc. A comprehensive review of YAG-based optical fibers is provided in this paper. Firstly, the fabrication processes of YAG-based optical fibers are summarized and the structure and properties of fibers are classified and compared. Secondly, according to the optical wavelength regions, rare earth-doped YAG-based optical fibers for the applications of single-frequency and mode-locked fiber lasers are summarized. Lastly, the development challenges in both the fabrication and applications of YAG-based optical fibers are discussed.

Impact of fiber sizes on multi-fiber filter performance using coupled Eulerian-Lagrangian and Immersed boundary

Fibrous filters are widely used to remove particles from gas-solid flows. In the present research, the potential to enhance the collection efficiency of fibrous filters was investigated by increasing the number of filter rows and using varying sizes of square fibers. A two dimensional model was used to simulate the transport and deposition of particles, employing the developed Eulerian-Lagrangian solver coupled with the Immersed Boundary (IB) method. Several structures of filter fibers including the equal and unequal fibers in the arrangement of two, four and six rows were investigated. The results showed increasing the size difference between large and small fibers in the filter media increases the collection efficiency and pressure drop simultaneously. To find the effective structure of enhancing the filter performance, the quality factor was considered. The results of quality factor showed that using unequal fibers has an advantage over increasing the number of rows in an equal-fiber structure to increase the collection efficiency. Therefore, using the unequal fibers with the growth rate of 1.2 to 1.4, are more effective than increasing the number of rows in equal fiber structures.

Biodegradable Poly (L-Lactic acid) Fibrous Membrane with Ribbon-Structured Fibers and Ultrafine Nanofibers Enhances Air Filtration Performance.

Here, the poly (l-lactic acid) (PLLA) membrane with multi-structured networks (MSN) is successfully prepared by electrospinning technology for the first time. It is composed of micron-sized ribbon-structured fibers and ultrafine nanofibers with a diameter of tens of nanometers, and they are connected to form the new network structure. Thanks to the special fiber morphology and structure, the interception and electrostatic adsorption ability for against atmospheric particulate matter (PM) are significantly enhanced, and the resistance to airflow is reduced due to the "slip effect" caused by ultrafine nanofibers. The PLLA MSN membrane shows excellent filtration performance with ultra-high filtration efficiency (>99.9% for PM2.5 and >99.5% for PM0.3) and ultra-low pressure drop (≈20Pa). It has demonstrated filtration performance that even exceeds current non-biodegradable polymer materials, laying the foundation for future applications of biodegradable PLLA in the field of air filtration. In addition, this new structure also provides a new idea for optimizing the performance of other polymer materials.

Study on the Biological Drug Enterocol’s Effect on the Nile Tilapia Breeding

Background Nile tilapia (Oreochromis niloticus) is a promising fish species for fish farming development in the Republic of Kazakhstan. It exemplifies a balanced and fast-growing source of flesh for future food production. In this context, optimising breeding methods is crucial for a high flesh yield and a safe product. The study delves into the potential of the Enterocol drug in enhancing Nile tilapia breeding, focusing on assessing muscle state and blood parameters. Objects Two groups of fish were utilized, with 20 specimens in each group. One set was the control group, and the other was the experimental group. The single difference between the fish groups was the Enterocol consumption by the experimental specimens, which were given an E. coli 64G strain concentration of 108 CFU in mL and a 5% daily dose of fish body weight three times daily for two months. Methods Blood parameters were analysed to assess the health of the fish groups. Subsequently, classical pathological methods were employed, such as macroscopic and microscopic assessments of each group's fish material. A histological analysis was also performed to assess the condition of the muscles. Results Examining the experimental group's muscles revealed a significant average increase in fish mass and 6.74% total body weight growth. Moreover, the total thickness of the muscle layer decreased as villi height increased, indicating a clear fibre structure. Haematological analysis unveiled elevated levels of haemoglobin, erythrocytes, leucocytes, and total protein in the experimental fish group, indicating improved health. These findings underscore the potential of the Enterocol drug in enhancing fish health and productivity. Conclusion Based on the results, it can be concluded that using Enterocol in fish breeding plants can effectively enhance flesh quality and safety, providing a secure and reliable solution for the aquaculture industry.

Oriented cellulose hydrogel: Directed tissue regeneration for reducing corneal leukoplakia and managing fungal corneal ulcers

Fungal corneal ulcer is one of the leading causes of corneal blindness in developing countries. Corneal scars such as leukoplakia are formed due to inflammation, oxidative stress and non-directed repair, which seriously affect the patients' subsequent visual and life quality. In this study, drawing inspiration from the oriented structure of collagen fibers within the corneal stroma, we first proposed the directional arrangement of CuTA-CMHT hydrogel system at micro and macro scales based on the 3D printing extrusion method combined with secondary patterning. It played an antifungal role and induced oriented repair in therapy of fungal corneal ulcer. The results showed that it effectively inhibited Candida albicans, Aspergillus Niger, Fusarium sapropelum, which mainly affects TNF, NF-kappa B, and HIF-1 signaling pathways, achieving effective antifungal functions. More importantly, the fibroblasts interacted with extracellular matrix (ECM) of corneal stroma through formation of focal adhesions, promoted the proliferation and directional migration of cells in vitro, induced the directional alignment of collagen fibers and corneal stromal orthogonally oriented repair in vivo. This process is mainly associated with MYLK, MYL9, and ITGA3 molecules. Furthermore, the downregulation the growth factors TGF-β and PDGF-β inhibits myofibroblast development and reduces scar-type ECM production, thereby reducing corneal leukoplakia. It also activates the PI3K-AKT signaling pathway, promoting corneal healing. In conclusion, the oriented CuTA-CMHT hydrogel system mimics the orthogonal arrangement of collagen fibers, inhibits inflammation, eliminates reactive oxygen species, and reduces corneal leukoplakia, which is of great significance in the treatment of fungal corneal ulcer and is expected to write a new chapter in corneal tissue engineering.

A label-free immunosensor based on E-SMS optical fiber structure for rapid Ag85B detection of tuberculosis

Tuberculosis, caused by Mycobacterium tuberculosis bacillus, is one of the most prevalent, widespread, infectious, and deadliest diseases in the world. In this work, a compact and sensitive biosensor based on an etched single-mode–multimode–single-mode (E-SMS) optical fiber structure was developed for the rapid detection of Mycobacterium tuberculosis Ag85B protein in phosphate buffered saline solution. This biosensor, based on the multimode interference produced into an E-SMS structure, was fabricated by chemical etching of the cladding region of the multimode fiber, followed by the immobilization of the anti-Ag85B antibody on the surface of the etched region. The functionalized E-SMS biosensor provided high selectivity in the detection of Ag85B protein, with the ability to detect biological interactions in a range of 1.31 µg/mL to 4.36 µg/mL, with a sensitivity of 2.3 nm/(µg/mL); also, signal was even obtained at concentrations as low as 80 ng/mL. This sensitive label-free biosensing technology could contribute significantly improve Mycobacterium tuberculosis detection, management in clinical diagnosis, and medical treatment of infected patients.