Sensor Surface Research Articles

A Flexible Double-Sided Curvature Sensor Array for Use in Soft Robotics.

This paper describes the design, fabrication, integration, characterization, and demonstration of a novel flexible double-sided curvature sensor array for use in soft robotics. The paper explores the performance and potential applications of a piezoresistive sensor array consisting of four gold strain gauges on a flexible polyimide (PI) substrate arranged in a Wheatstone bridge configuration. Multiple sensor strips were arranged like the fingers of a hand. Integrating Shape Memory Alloy (SMA) foils alongside the fingers was explored to mimic a human hand-gripping motion controlled with temperature, while curvature sensor array strips measure the resulting finger shapes. Moreover, object sensing in a flexible granular material gripper was demonstrated. The sensors were embedded within Polydimethylsiloxane (PDMS) to enhance their tactile feel and adhesive properties. The findings of this study are promising for future applications, particularly in robotics and prosthetics, as the ability to accurately mimic human hand movements and reconstruct sensor surfaces paves the way for robotic hand functionality.

High fidelity detection of miRNAs from complex physiological samples through electrochemical nanosensors empowered by proximity catalysis and magnetic separation

Electrochemical detection of miRNA biomarkers in complex physiological samples holds great promise for accurate evaluation of tumor burden in the perioperative period, yet limited by reproducibility and bias issues. Here, nanosensors installed with hybrid probes that responsively release catalytic DNAzymes (G-quadruplexes/hemin) were developed to solve the fidelity challenge in an immobilization-free detection. miRNA targets triggered toehold-mediated strand displacement reactions on the sensor surface and resulted in amplified shedding of DNAzymes. Subsequently, the interference background was removed by Fe3O4 core-facilitated magnetic separation. Binding aptamers of the electrochemical reporter (dopamine) were tethered closely to the catalytic units for boosting H2O2-mediated oxidation through proximity catalysis. The one-to-many conversion by dual amplification from biological-chemical catalysis facilitated sufficient homogeneous sensing signals on electrodes. Thereby, the nanosensor exhibited a low detection limit (2.08 fM), and high reproducibility (relative standard deviation of 1.99%). Most importantly, smaller variations (RSD of 0.51–1.04%) of quantified miRNAs were observed for detection from cell lysates, multiplexed detection from unprocessed serum, and successful discrimination of small upregulations in lysates of tumor tissue samples. The nanosensor showed superior diagnostic performance with an area under curve (AUC) of 0.97 and 94% accuracy in classifying breast cancer patients and healthy donors. These findings demonstrated the synergy of signal amplification and interference removal in achieving high-fidelity miRNA detection for practical clinical applications.

Development of an Aptamer-Based QCM-D Biosensor for the Detection of Thrombin Using Supported Lipid Bilayers as Surface Functionalization.

Biosensors play an important role in numerous research fields. Quartz crystal microbalances with dissipation monitoring (QCM-Ds) are sensitive devices, and binding events can be observed in real-time. In combination with aptamers, they have great potential for selective and label-free detection of various targets. In this study, an alternative surface functionalization for a QCM-D-based aptasensor was developed, which mimics an artificial cell membrane and thus creates a physiologically close environment for the binding of the target to the sensor. Vesicle spreading was used to form a supported lipid bilayer (SLB) of 1-palmitoyl-2-oleoyl-glycero-3-phosphocholine (POPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphethanolamine-N-(cap biotinyl) (biotin-PE). The SLB was then coated with streptavidin followed by applying a biotinylated aptamer against thrombin. SLB formation was investigated in terms of temperature and composition. Temperatures of 25 °C and below led to incomplete SLB formation, whereas a full bilayer was built at higher temperatures. We observed only a small influence of the content of biotinylated lipids in the mixture on the further binding of streptavidin. The functionalization of the sensor surface with the thrombin aptamer and the subsequent thrombin binding were investigated at different concentrations. The sensor could be reconstituted by incubation with a 5 M urea solution, which resulted in the release of the thrombin from the sensor surface. Thereafter, it was possible to rebind thrombin. Thrombin in spiked samples of human serum was successfully detected. The developed system can be easily applied to other target analytes using the desired aptamers.

Heuristic algorithms for design of integrated monitoring of geologic carbon storage sites

Designs for Risk Evaluation and Management (DREAM) is a tool developed under the National Risk Assessment Partnership (NRAP) to enhance geologic carbon storage safety and efficiency. Using potential leakage scenarios generated externally by the users preferred history-matching approach, DREAM constructs ideal combinations of sensor locations in the right place at the right time to detect as many leaks as possible, detect them as early as possible, and minimize cost. This user-friendly tool, developed in Java, features a window-based GUI for input and a 3D visualization tool for viewing the domain space and optimized monitoring plans. DREAM's latest version accommodates real-world usage by allowing for joint optimization of wellbore point sensor placements and surface geophysics survey geometries, and by using more efficient multi-objective optimization algorithms. In an example shown here, these two improvements combined allow us to support containment assurance and go from detecting 80–90 % of the potential CO2 leakage to +99.7 %, a step-change improvement that can make the deciding difference in whether a site is suitable for geologic carbon storage. Though developed for geologic carbon storage, this tool would be equally applicable in many surface or offshore environmental monitoring projects.

Peptide-Based Recognition Agents of Histamine: A Biopanning Approach with Enhanced Specificity.

Histamine is a biogenic amine that poses a potential threat to public health due to its toxicological effects. In this study, we identified histamine-binding peptides by screening a random 12-mer peptide library, employing a novel biopanning approach that excluded histidine-binding sequences in the final round. This additional step enhanced the selectivity of the peptides and prevented interference from histidine during detection. The binding affinities of synthesized peptides to histamine were assessed using isothermal titration calorimetry (ITC). Among the identified peptides, HBF10 (SGFRDGIEDFLW) and HBF26 (IPLENQHKIYST) showed significant affinity to histamine, with Ka values of 2.56×104 (M-1) and 8.94×104 (M-1), respectively. Notably, the identified peptides did not demonstrate binding affinity towards histidine, despite its structural similarity to histamine. Subsequently, the surface plasmon resonance (SPR) sensor surface was prepared by immobilizing the peptide HBF26 to investigate the potential of the peptide as a recognition agent for histamine detection. The findings suggest that the identified peptides have an affinity to histamine specifically, showcasing their potential applications as diagnostic agents with specific targeting capabilities.

Real-time biomolecule detection using GMR chip-based sensor with green-synthesized Fe3O4/rGO nanocomposites as magnetic labels

The availability of a rapid, low-cost, and easy-to-use device to monitor the bovine serum albumin (BSA) level in human blood and urine is vital in early disease detection. This work reports a biosensor system based on a giant magnetoresistance (GMR) chip as a transducer integrated with Fe3O4/rGO magnetic labels for BSA protein detection. The commercial chip AAL024 is utilized as the GMR sensor, combined with an Arduino microcontroller (AM) and a basic differential amplifier to acquire the digital output voltage. The Fe3O4/rGO nanocomposites were synthesized by a hybrid process based on the green synthesis route utilizing plant extracts. The nanocomposites exhibit superparamagnetic behavior, affecting the magnetic label detection quality. In investigating sensor performance, Fe3O4/rGO nanocomposites can generate sufficient stray fields under a 4 Oe of bias magnetic field (HB). A larger net stray field is produced by a higher concentration of magnetic labels, which suggests that there are more Fe3O4 nanoparticles attached to the sensor surface. Further, the effectiveness of the biosensor was evaluated by detecting the BSA protein. As a result, a high sensitivity of 22.98 mV/(mg/mL) and a low limit of detection (LOD) of 0.3 mg/mL were obtained in detecting Fe3O4/rGO(5:1)/BSA with a voltage signal that can be collected in 30 s. Besides its high sensitivity, low LOD, and fast detection, the sensor exhibits remarkable reproducibility and stability, as evidenced by the relative signal deviation (RSD) range of 1.1 – 5.6%. These findings demonstrate that the GMR chip-based sensor integrated with Fe3O4/rGO magnetic labels provides a simple biosensor system with real-time electronic readout.

A Flexible Terahertz Metamaterial Sensor for Pesticide Sensing and Detection.

Terahertz (THz) waves have garnered significant interest across various fields, particularly in high-sensitivity sensing applications. Metamaterials can be employed in THz sensors, specifically for refractive index sensing and pesticide detection due to their high-sensitivity characteristics. In this Article, a dual-band flexible THz metamaterial sensor based on polyimide is proposed for refractive index and pesticide sensing, which is fabricated using ultraviolet (UV) lithography technology and measured by a THz time-domain spectroscope (TDS) system. The resonant frequencies of the sensor are at 0.37 and 1.13 THz, with transmission rates of 2.9% and 0.3%, respectively. With an analyte layer attached to the sensor's surface, the sensitivity of refractive index sensing can be calculated as 0.09 and 0.28 THz/RIU (refractive index unit) at the two resonant frequencies. In order to validate the exceptional pesticide sensing performance of the sensor, chlorpyrifos-methyl acetone solutions with various concentrations are added on it. Furthermore, a monolayer of graphene is coated on the sensor's surface, which is proved capable of improving pesticide sensing sensitivity at low concentrations due to strong π-π stacking interactions with π-electrons in chlorpyrifos-methyl solutions. Therefore, the graphene-coated sensor can be utilized in detecting pesticide solutions with low concentrations, and the sensor without graphene is preferred for high concentration detection. This work provides a novel option for the THz metamaterial sensor with high sensitivity covering a wide pesticide concentration range.

On-site SNP discrimination of Monkeypox viral DNA at room temperature using dCas9-enhanced extended-gate field-effect transistor

During the COVID-19 pandemic, there was heightened concern about the sudden spread of viral diseases. As the threat of coronavirus transmission began to diminish, a subsequent outbreak caused by monkeypox virus (MPXV) emerged in Europe and North America. Notably, MPXV infection tends to be transmitted through sexual contact, increasing the difficulty of tracing the infection route through passive testing. As a result, there is a pressing need for cost-effective, precise, and rapid on-site screening techniques to detect MPXV. Recently, the CRISPR system, known as a genome editing tool, has been used as a rapid on-site diagnostic tool for detecting nucleic acids mostly through the use of Cas12a and Cas13a. Intriguingly, deficient Cas9 (dCas9) can recognize specific double-stranded DNA (dsDNA) sequences and bind to complementary DNA sequences. Here, we devised an innovative digital field-diagnosis platform that can be readily employed in clinical settings. This platform combines an ultrasensitive field-effect transistor (FET) with the dCas9 system, enabling quantitative analysis of biomarkers. Our dCas9-EG-FET can directly detect viral dsDNA without any amplification or pretreatment. When the dCas9 of our dCas9-EG-FET system recognizes the specific target viral DNA, the EG-FET system provides voltage differences by using FET features that measure the ion concentration on the surface of the FET sensor. Furthermore, it takes only 20 min to detect MPXV DNA using our dCas9-EG-FET system at room temperature (RT), and this system can be used to effectively distinguish single-point mutations with high sensitivity. Our findings suggest that the use of a CRISPRCas-based biosensor could lead to an effective strategy for screening for infectious diseases.

Label-free and label-based electrochemical detection of disease biomarker proteins.

Biosensors, analytical devices integrating biological sensing elements with physicochemical transducers, have gained prominence as rapid and convenient tools for monitoring human health status using biochemical analytes. Due to its cost-effectiveness, simplicity, portability, and user-friendliness, electrochemical detection has emerged as a widely adopted method in biosensor applications. Crucially, biosensors enable early disease diagnosis by detecting protein biomarkers associated with various conditions. These biomarkers offer an objective indication of medical conditions that can be accurately observed from outside the patient. This review comprehensively documents both label-free and labelled detection methods in electrochemical biosensor techniques. Label-free detection mechanisms elicit response signals upon analyte molecule binding to the sensor surface, while labelled detection employs molecular labels such as enzymes, nanoparticles, and fluorescent tags. The selection between label-free and labelled detection methods depends on various factors, including the biomolecular compound used, analyte type and biological binding site, biosensor design, sample volume, operational costs, analysis time, and desired detection limit. Focusing on the past six years, this review highlights the application of label-free and labelled electrochemical biosensors for detecting protein biomarkers of diseases.

Visible light enhanced selective benzene response of hexagonal atomic structured CuS microcloves

We have reported CuS microcloves (MCs) for highly selective detection of benzene using scanning kelvin probe (SKP) technique. The electron microscopy investigations revealed the formation of clove shaped CuS with a size of about 1–2 µm at 180 °C and 6 h. The time of reaction significantly affected the crystallinity as well as the morphology of resulting CuS materials. The investigations on adsorption behavior of different types of common volatile organic compounds (VOCs) with varying charge and nature revealed an outstanding selectivity towards benzene when compared to other VOCs. The difference in work function between gold tip and sensor surface modified with CuS MCs was decreased under the exposure of light, most likely caused by transfer of electrons to conduction band of CuS under illumination of light. As a result, the CuS MCs showed enhanced photo response in visible light exposure in the presence of benzene. A chemiresistive type sensor device was fabricated using CuS MCs and exposed to benzene vapor in a concentration ranging from 2.8 to 11.2 ppm. The sensitivity was found to be 1.63 × 10-3 ppm−1. Notably, a rapid response time of ∼6 s and recovery time of ∼ 16 s was achieved for the sensor at a benzene concentration of 5.6 ppm at room temperature. Also, considerable and repeatable sensor response was observed for 560 ppb of benzene vapor at 70 °C. Hence, these results suggested that the CuS MCs have huge potential as novel material for selective benzene detection in gas phase towards breath analysis and other environmental monitoring.

Characterization of a perfect sinusoidal grating profile using an artificial neural network for plasmonic-based sensors

In this paper, we present a system intended to detect a targeted perfect sinusoidal profile of a diffraction grating during its manufactured process. Indeed, the sinusoidal nature of the periodic structure is essential to ensure optimal efficiency of specific applications as plasmonic sensors (surface plasmon resonance -based sensors). A neural network is implemented to characterize the geometrical shape of the structure under testing at the end of the laser interference lithography process. This decision tool operates in classifier mode prior to further processing. Then, the geometrical parameters of the structure can be reliably determined if necessary. Two solutions can be considered: the detection of a fixed geometrical shape operating on a binary mode and the identification of a geometrical shape from a limited number of profiles. These methods are validated in the context of plasmonic sensors on experimental sinusoidal grating structures with a grating period of 627 nm.

A highly stable electrochemical sensor with antifouling and antibacterial capabilities for mercury ion detection in seawater

The monitoring of heavy metal ions in ocean is crucial for environment protection and assessment of seawater quality. However, the detection of heavy metal ions in seawater with electrochemical sensors, especially for long-term monitoring, always faces challenges due to marine biofouling caused by the nonspecific adsorption of microbial and biomolecules. Herein, an electrochemical aptasensor, integrating both antifouling and antibacterial properties, was developed for the detection of Hg2+ in the ocean. In this electrochemical aptasensor, eco-friendly peptides with superior hydrophilicity served as anti-biofouling materials, preventing nonspecific adsorption on the sensing interface, while silver nanoparticles were employed to eliminate bacteria. Subsequently, a ferrocene-modified aptamer was employed for the specific recognition of Hg2+, leveraging the aptamer's ability to fold into a thymine-Hg2+-thymine (T-Hg2+-T) structure upon interaction, and bringing ferrocene nearer to the sensor surface, significantly amplifying the electrochemical response. The prepared electrochemical aptasensor significantly reduced the nonspecific adsorption in seawater while maintaining sensitive electrochemical response. Furthermore, the biosensor exhibited a linear response range of 0.01–100 nM with a detection limit of 2.30 pM, and realized the accurate monitoring of mercury ions in real marine environment. The research results offer new insights into the preparation of marine antifouling sensing devices, and it is expected that sensors with antifouling and antimicrobial capabilities will find broad applications in the monitoring of marine pollutants.

Ammonia-trapping multilayer polymer urease film amplifier coated surface plasmon resonance sensor for ultra-sensitive urea detection

In this paper, we have developed a new urea signal amplification technology based on a multilayer urease polymer film self-assembly structure for the first time, enabling the realization of ultra-accurate urea optical detection. We demonstrate the effectiveness of this technique based on surface plasmon resonance (SPR) platform. When the urea signal amplifier is combined with SPR sensors, multilayer urease polymer film contacts with urea molecules, the urea molecules are oxidated into NH3 and CO2, causing the pH increase, which weakens the electrostatic interaction between different polymer layers and induces the RI reduction of the multilayer urease film, thereby causing the shift of the SPR spectrum. Experiment results confirm that urea sensitivity has been improved 12-fold, and the limit of detection (LOD) has been optimized to less than 10−3 mmol/L. Furthermore, the anti-interference has been improved 22.8-fold and is kept even the interference signal strength increases by 100 times. Moreover, multilayered urease polymer leads to the increase of urease on the sensor surface, thus expanding the detection range of urea by 3.5 times. This provides a new way to solve the contradiction between high sensitivity and large measurement range of optical fiber biosensor. Importantly, the concept of using enzyme-loaded polymer films for signal amplification can be adapted for the detection of various other biomolecules by replacing the enzyme with a specific recognition element for the target molecule. This opens doors for developing highly sensitive and specific biosensors for diverse applications in healthcare, environmental monitoring, and food safety.

Cesium ion-guided detection of trichloroethylene in air

Whereas the close associations of cesium ion with organochlorine compounds have been previously documented, the present report is the first attempt to exploit these interactions to create a trichloroethylene (TCE)-selective sensor. Gold monolayer-protected clusters peripherally functionalized with Cs+ ions were used to prepare a chemiresistance film on MEMS-fabricated interdigitated electrodes. Vapor sensing properties of the cesium-rich chemiresistor were determined using a panel of chlorinated hydrocarbons including TCE as well as polar and non-polar VOCs for comparison. The sensor was selective and highly sensitive toward VOCs containing a 1,2-dichloro group at concentrations as low as 0.1 ppm. The results suggest the key interaction contributing to sensor response is a bidentate, metallocycle-like coordination of the 1,2-dichloro group to the cesium cations at the sensor surface.

Optimized Fabrication of Carbon-Fiber Microbiosensors for Codetection of Glucose and Dopamine in Brain Tissue.

Dopamine (DA) signaling is critically important in striatal function, and this metabolically demanding process is fueled largely by glucose. However, DA and glucose are typically studied independently and, as such, the precise relationship between DA release and glucose availability remains unclear. Fast-scan cyclic voltammetry (FSCV) is commonly coupled with carbon-fiber microelectrodes to study DA transients. These microelectrodes can be modified with glucose oxidase (GOx) to generate microbiosensors capable of simultaneously quantifying real-time and physiologically relevant fluctuations of glucose, a nonelectrochemically active substrate, and DA, which is readily oxidized and reduced at the electrode surface. A chitosan hydrogel can be electrodeposited to entrap the oxidase enzyme on the sensor surface for stable, sensitive, and selective codetection of glucose and DA using FSCV. This strategy can also be used to entrap lactate oxidase on the carbon-fiber surface for codetection of lactate and DA. However, these custom probes are individually fabricated by hand, and performance is variable. This study characterizes the physical nature of the hydrogel and its effects on the acquired electrochemical data in the detection of glucose (2.6 mM) and DA (1 μM). The results demonstrate that the electrodeposition of the hydrogel membrane is improved using a linear potential sweep rather than a direct step to the target potential. Electrochemical impedance spectroscopy data relate information on the physical nature of the electrode/solution interface to the electrochemical performance of bare and enzyme-modified carbon-fiber microelectrodes. The electrodeposition waveform and scan rate were characterized for optimal membrane formation and performance. Finally, codetection of both DA/glucose and DA/lactate was demonstrated in intact rat striatum using probes fabricated according to the optimized protocol. Overall, this work improves the reliable fabrication of carbon-fiber microbiosensors for codetection of DA and important energetic substrates that are locally delivered to the recording site to meet metabolic demand.

NO2 and NH3 detection using work function measurement of solvothermal synthesised ZnO–NiO nanocomposites: a case study

Work function measurement using Kelvin probe method has been demonstrated as an effective and novel approach towards detection of NH3 and NO2 gases using ZnO–NiO based nanocomposites. For this the nanocomposites were synthesised in different compositions using the solvothermal method. Formation of ZnO–NiO nanocomposites was confirmed using XRD and EDS studies. It is found that the nanoparticle morphology of NiO changes with different percentages of Zn addition. The work function of the sensing film was found to decrease and increase upon exposure to NH3 (1.51) and NO2 (1.18) gases owing to the reducing and oxidising nature of the test gases. Of the different composites, Zn0.75Ni0.25O exhibited highest sensor response towards the test gases. The increased response is attributed to the nanostructured morphology of the nanocomposite and the formation and collapse of the p-n heterojunction formed between p-type NiO and n-type ZnO. Besides, incorporation of NiO enhances the oxygen adsorption on the sensor surface assigned to the Ni2+ ions getting readily oxidised to Ni3+. Our results clearly suggest that the work function measurements could also be used as an effective way for NO2 and NH3 detection.

The Oxidase Mimicking Activity of MnOx NPs/Co3O4 NPs Hybrid Nanozyme for Glucose Oxidation

Herein, the hybrid nanozyme MnOx NPs/Co3O4 NPs on indium tin oxide coated glass substrate (ITO) was manufactured by imparting the porous morphology with its distinct merits: its surface valence states, oxygen vacancies, large surface area, and abundant active sites. The oxidase-like activity was investigated via the catalytic oxidation of chromogenic substrate in the presence of glucose visualized by the eyes. MnOx NPs containing Mn2+ and Mn3+ have a superior ability to oxidize glucose by reducing dissolved oxygen and producing H2O2. Co3O4 NPs, in turn, reduce H2O2 with concomitant 3,3′,5,5′-tetramethylbenzidine (TMB) oxidization. Thus, the nanozyme mimics the dual roles of glucose oxidase and peroxidase. The oxidase-like activity of hybrid nanozyme for glucose was found to be higher than those of single components. The nanozyme responded to glucose with a linear range from 60 µM to 1200 μM. The acceptable performance is probably due to the facilitated access of glucose to the proximity of the sensor surface. Good reproducibility was accomplished by virtue of the meticulous construction of NPs. Without functionalization and enzyme utilization, the fabricated nanozyme holds promise as a substitute for peroxidase and oxidase for detecting glucose.

A Silicon-Based ROTE Sensor for High-Q and Label-Free Carcinoembryonic Antigen Detection.

This paper presents a biosensor based on the resonant optical tunneling effect (ROTE) for detecting a carcinoembryonic antigen (CEA). In this design, sensing is accomplished through the interaction of the evanescent wave with the CEA immobilized on the sensor's surface. When CEA binds to the anti-CEA, it alters the effective refractive index (RI) on the sensor's surface, leading to shifts in wavelength. This shift can be identified through the cascade coupling of the FP cavity and ROTE cavity in the same mode. Experimental results further show that the shift in resonance wavelength increases with the concentration of CEA. The biosensor responded linearly to CEA concentrations ranging from 1 to 5 ng/mL with a limit of detection (LOD) of 0.5 ng/mL and a total Q factor of 9500. This research introduces a new avenue for identifying biomolecules and cancer biomarkers, which are crucial for early cancer detection.

ZIF-8 functionalized S-tapered fiber-optic sensor for polystyrene nanoplastics detection by electrostatic adsorption

Microplastic (MP) residues in marine have become an increasingly serious environmental pollution issue, and in recent years the detection of MPs in marine started to attract worldwide research interests. Optical-fiber-based environmental sensors have been extensively employed for their several merits such as high sensitivity, pressure resistance, compactness and ease of constructing communication networks. However, fiber-optic refractive index sensors are not specifically developed for distinguishing MPs from other inorganic particles suspended in water. In this paper, an metal-organic framework (MOF) ZIF-8 functionalized S-tapered fiber (STF) sensor is proposed for specific detection of polystyrene nanoplastics (PSNPs) in aqueous environment. ZIF-8 coordination nanoporous polymers with different film thickness were immobilized over the surface of the fabricated STF structure based on self-growth technique and yielding a large surface area over the sensor surface. High sensitivity detection can be achieved by converting the concentration perturbation of PSNPs into evanescent waves over the ZIF-8 functionalized STF surface through the strong electrostatic adsorption effect and π-π stacking, while the fabricated sensor is insensitive to gravels with silica as the primary component in water. It is found that the proposed detector with 18 film layers achieves a sensitivity up to 114.1353nm/%(w/v) for the PSNPs concentration range of 0.01 %(w/v) to 0.08 %(w/v).

Development of a biophotonic fiber sensor using direct-taper and anti-taper techniques with seven-core and four-core fiber for the detection of doxorubicin in cancer treatment

Doxorubicin (DOX) is an important drug for cancer treatment, but its clinical application is limited due to its toxicity and side effects. Therefore, detecting the concentration of DOX during treatment is crucial for enhancing efficacy and reducing side effects. In this study, the authors developed a biophotonic fiber sensor based on localized surface plasmon resonance (LSPR) with the multimode fiber (MMF)-four core fiber (FCF)-seven core fiber (SCF)-MMF-based direct-taper and anti-taper structures for the specific detection of DOX. Compared to other detection methods, it has the advantages of high sensitivity, low cost, and strong anti-interference ability. In this experiment, multi-walled carbon nanotubes (MWCNTs), cerium-oxide nanorods (CeO2-NRs), and gold nanoparticles (AuNPs) were immobilized on the probe surface to enhance the sensor's biocompatibility. MWCNTs and CeO2-NRs provided more binding sites for the fixation of AuNPs. By immobilizing AuNPs on the surface, the LSPR was stimulated by the evanescent field to detect DOX. The sensor surface was functionalized with DOX aptamers for specific detection, enhancing its specificity. The experiments demonstrated that within a linear detection range of 0-10 µM, the sensitivity of the sensor is 0.77 nm/µM, and the limit of detection (LoD) is 0.42 µM. Additionally, the probe's repeatability, reproducibility, stability, and selectivity were evaluated, indicating that the probe has high potential for detecting DOX during cancer treatment.