Wide Detection Research Articles

A 1–6.5 Gbps dual-loop CDR design with Coarse-fine Tuning VCO and modified DQFD

A dual-loop CDR (Clock and Data Recovery) is presented to recover digital data from 1 to 6.5 Gbps. The presented frequency acquisition technique is based on full rate clock architecture. By utilizing modified Digital Quadri-correlator Frequency Detector (DQFD) and Frequency Increment/Decrement Control circuit, the lock-in range is improved. Furthermore, the issue of state loss during wide frequency range detection is successfully mitigated. The inclusion of two control wires in the Coarse-fine Tuning VCO enables the utilization of separate loop filters in the dual loops, resulting in a more effective reduction of noise and jitter. Utilizing a 40-nm CMOS process, the presented CDR design has been implemented. The post-layout simulation results at 6.5 Gbps shows a P2P and root-mean-square jitter values are 17.1 ps and 5.79 ps, respectively, for the retimed data.

A high-performance light-driven photoelectrochemical sensor based on CdIn2S4/b-TiO2/GO type-II 2D/3D heterojunction for the detection of baicalein in natural plant samples

The remarkable pharmacological activities of flavonoids and their effects on human health have prompted many studies. To solve the problem that flavonoids are difficult to be accurately quantified, a novel photoelectrochemical (PEC) sensor based on CdIn2S4/b-TiO2/GO was created to detect the baicalein (BCA). By using physical ultrasonic compounding, a straightforward and effective CdIn2S4/b-TiO2/GO composite was created. The composite’s photoelectric effect was 14 times greater than that of the individual material. When BCA was present, a flavonoid-TiO2 nanoconjugate was formed based on the interaction between b-TiO2 and BCA. This interaction prevented the formation and decreased charge transfer of photoporous holes, resulting in a significant decline in photocurrent. Therefore, the PEC sensor based on the change of the electrode surface state can realize the sensitive detection of BCA. The PEC sensor has a wide linear detection range of 1 nM − 30 μM with a limit of detection of 0.5 nM. In addition, the sensor has exhibited excellent accuracy in detecting BCA in the roots and leaves of Scutellaria baicalensis, which can be used for the detection of actual samples.

Click-response-driven high-speed and ultrasensitive electrochemical sensing interface: Addressing its accuracy challenge

For electrochemical sensors, maintaining accuracy while achieving sensitive detection is of paramount importance. The fixation of the signal substance as one of the main steps in the construction process of a sensor has a significant impact on the accuracy. Currently, physical and chemical methods are the primary approaches for the fixation of the signal substance, which have the following issues. The accuracy of a sensor may be affected by the instability resulting from the physical immobilization of the signal substance and the chemical immobilization process is typically time-consuming. To overcome these obstacles, the ultra-sensitive electrochemical sensing interface is constructed by click reaction to achieve accurate and rapid detection of tumor biomarkers. After the formation of immune-sandwich structure in a test tube, a large amount of ethynylferrocene (EFc) molecules in the Zeolitic imidazolate frameworks (ZIF-8) immunoprobe are released under acidic conditions, followed by covalently linking to the substrate within 6 minutes through a click reaction. Under optimal conditions, the electrochemical sensor had an ultralow detection limit of 32.90 fg mL−1 for the model analyte (CEA) with a wide detection range from 100 fg mL−1 to 100 ng mL−1. This work provides a new perspective for designing electrochemical sensors with excellent performance.

Dual-mode detection of glucose based on pistol-like DNAzyme-mediated exonuclease-assisted signal cycle.

Detecting glucose accurately and sensitively from clinical samples like tears and saliva is still difficult. We have created a sensor that can detect glucose with high sensitivity and accuracy by combining the use of glucose oxidase (GOx) to catalyze glucose, a pistol-like DNAzyme (PLDz) to transform the signal, gold nanoparticles (AuNPs) to enhance the optical properties and the exonuclease-III (Exo-III) to amplify the signal. As a result, the proposed method exhibits a low detection limit of 7.5pM and a wide detection range covering seven orders of magnitude. The suggested dual-mode strategy provides a sensitive, precise and specific detection method for glucose. Another advantage is that the dual-mode technique significantly improves the precision and consistency of the measurements, demonstrating its immense potential for use in biomedical research and clinical diagnostics.

Fiber optic probe integrated with colloidal nanoparticles with directional diffraction selectivity for magnetic field vector detection

A fiber optic probe integrated with colloidal nanoparticles with directional diffraction selectivity is proposed for wide-bandwidth magnetic field vector detection. The probe is constructed with the multimode fiber in which the end-surface is integrated with the Fe3O4@C colloidal nanoparticles by a silicone tube. The colloidal nanoparticles form a three-dimensional photonic crystal structure by magnetic field for diffraction selectivity. The lattice constant and diffraction angle are adjusted by the intensity and direction of the magnetic field, respectively. Obtaining the directional diffraction light through the magnetic field-induced photonic band gap shift with the wavelength blue shift and reflectivity change is confirmed by theory and experiment. The results show that the maximum sensitivity reaches up to 19.7 nm/mT in response range from 13 mT to 200 mT. For vector detection, the peak wavelength shift from 740 nm to 485 nm and reflectance shift from 71% to 7% covering the 0–45° region is verified. In addition, the proposed method could decouple intensity and direction of the magnetic field completely. The fiber optic probe integrated with colloidal nanoparticles has wide detection range and high sensitivity with rapid response. It will open up new horizons for inspiring design and application of magnetic field vector detection in robot posture control and motion perception.

Highly-sensitive ultrathin flexible pressure sensor based on quasi-2D conductive network for human physiological signal monitoring

Ultrathin flexible pressure sensors are highly desirable for human physiological signal monitoring due to their portability and ability to conform to the body. However, existing ultrathin pressure sensors face challenges in balancing the sensitivity and their range. A spatial-dimensionally constrained strategy was proposed to construct an ultrathin active layer. In detail, multi-walled carbon nanotubes (MWCNTs) with an average length of ∼1.3 μm were intentionally spin-coated into a thin thermoplastic polyurethane (TPU) film with a thickness of 1.5 μm. By doing so, a quasi-2D MWCNTs conductive network is constructed, which enabled the sensor to have ultrahigh sensitivity of 27.04 kPa−1, a wide liner detection range of 0.2–24 kPa, ultrafast response time of 40 ms and a recovery time of 10 ms, and high durability in 1500 cycles under 0.2 kPa with loading/unloading frequency of 2 Hz. Thanks to this superior performance, the ultrathin pressure sensor can be used to monitor human movement and physiological signals, including finger touch, finger bending, wrist bending, and deep breathing. Moreover, the sensor can be attached to the side wall of the tip of the renal ureteroscope, allowing for the monitoring of renal pelvic pressure. Therefore, this spatial-dimensionally constrained strategy will open up a new way to fabricate highly sensitive ultrathin pressure sensors and have great application prospects in health monitoring.

Flexible and wearable sensor for in situ monitoring of gallic acid in plant leaves

Gallic acid (GA) is one of the main phenolic components naturally occurring in many plants and foods and has been a subject of increasing interest owing to its antioxidant and anti-mutagenic properties. This study introduces a novel flexible sensor designed for in situ detecting GA in plant leaves. The sensor employs a laser-induced graphene (LIG) flexible electrode, enhanced with MXene and molybdenum disulfide (MoS2) nanosheets. The MXene/MoS2/LIG flexible sensor not only demonstrates exceptional mechanical properties, covering a wide detection range of 1–1000 μM for GA, but also exhibits remarkable selectivity and stability. The as-prepared sensor was successfully applied to in situ determination of GA content in strawberry leaves under salt stress. This innovative sensor opens an attractive avenue for in situ measurement of metabolites in plant bodies with flexible electronics.

Hydrothermal Synthesis of Rare-earth Ferrate for Electrochemical Detection of 4-Aminophenol in Food Samples and Products

4-Aminophenol (4-APL/4-AP) is one of the toxic chemicals in the water sources. The electrochemical oxidation of 4-APL reaction was studied by electrochemical method with SPCE modified with perovskite rare-Earth ferrate (PrFeO3). The nanomaterials were characterize using various morphological analysis by TEM, XRD, FTIR, Raman, XPS. PrFeO3 needles modified SPCE demonstrated excellent electrocatalytic performance towards the electrooxidation of 4-APL under pH 7.0, having anodic peak current significantly higher than those of the bare SPCE. Using CV and amperometry method to analyse the sensor performance toward 4-APL detection. In CV, the synthetic sensor plays wide 4-APL detection range from 100–500 μM. In amperometry method, the sensor plays wide range of 4-APL detection from 0.03 to 1859 μM and the limit of detection is 0.014 μM. Mainly the proposed sensor material of PrFeO3/SPCE exhibit an excellent 4-APL detection carrying out in various food samples. Furthermore, regarding 4-APL analysis, PrFeO3/SPCE demonstrate outstanding selectivity, low limit of detection, repeatability, reproducibility, and operational stability.

MoSe2 nanosheets-based sensor for electrochemical detection of dopamine, ascorbic acid, and uric acid

There has been a growing interest in the field of transition metal dichalcogenide (TMD) materials and their potential applications in the field of electrochemical sensors. In the present work, molybdenum diselenide (MoSe2), as a typical representative of TMD, was prepared using a facile hydrothermal method and characterized in terms of its morphological and structural properties. Then, the obtained MoSe2 was dispersed in various solvents to investigate its electrocatalytic properties towards dopamine (DA), ascorbic acid (AA), and uric acid (UA). The electrochemical measurements revealed that deionized water is an effective solvent to disperse the MoSe2 and modify electrodes with the MoSe2 for electrochemical applications. Furthermore, the glassy carbon electrode (GCE) modified with the MoSe2, referred as GCE-MoSe2, was used as an electrochemical sensor to simultaneously detect the DA, AA, and UA. The GCE-MoSe2 exhibited wide linear detection with concentration ranges of 1–333 µM for DA, 50–3440 µM for AA, and 5–1146 µM for UA in phosphate buffer solution and low detection limits (LODs) of 0.57 µM, 13.7 µM, and 1.75 µM, respectively. The electrode further displayed good selectivity, reproducibility, and stability. This work provides valuable insights on constructing electrochemical sensing devices with high analytical performance using the important two-dimensional (2D) TMD materials.

SPR based dual parameter wide range curling pot shaped photonic crystal fiber sensor

This article proposes a curling pot shaped photonic crystal fiber (PCF) sensor based on surface plasmon resonance (SPR), which utilizes two parallel polished surfaces in the cladding to achieve dual parameter measurements of liquid refractive index (RI) and temperature. The mode characteristics and sensing performance of the designed PCF sensor are studied using the finite element method, and the effects of changes in structural parameters such as pore radius, spacing, and gold film thickness on the resonance spectrum are analyzed. The sensing accuracy of the sensor is insensitive to the change of structural parameters, and it has the characteristics of a wide detection range, high sensitivity, and easy manufacture. When the measured RI is in the range of 1.33∼1.42, the maximum RI sensitivity is 20400 nm RIU−1, and the maximum FOM is 483.3 RIU−1. When the temperature ranges from −10 °C to 100 °C, the maximum sensitivity is 15.4 nm °C−1, and the maximum FOM is 0.43 RIU−1. The tight structure design of the sensor core close to the polishing surface and the anti-spill light design with a uniform arrangement of air holes enhance the SPR effect, which is the essential reason for achieving a wide detection range and high sensitivity.

Double formant PCF-SPR sensor with high sensitivity and wide detection range for detecting analytes with low refractive indexes

Double formant PCF-SPR sensor with high sensitivity and wide detection range for detecting analytes with low refractive indexes

High-performance humidity sensors based on SnO2/Ti3C2Tx nanocomposites coated on porous graphene electrodes

This study proposes the synthesis of SnO2/Ti3C2Tx composites on porous graphene electrodes (PGEs) for high-performance humidity sensors. In the heterojunction structure of SnO2/Ti3C2Tx composites, SnO2 nanoparticles prevented the layered structure of Ti3C2Tx to collapse and restack. Moreover, the high specific surface area of the SnO2/Ti3C2Tx composites provided more adsorption sites that improved their response. Porous graphene was fabricated by a fiber laser-induced process on the polyimide film as an electrode layer for flexible humidity sensors. The characteristics of the SnO2/Ti3C2Tx composites and PGEs were examined and investigated. SnO2/Ti3C2Tx composites were drop-cast on PGEs to fabricate the humidity sensor. Furthermore, the response of humidity sensors was tested in various RHs. The performance of the proposed humidity sensor demonstrated a wide detection range of 11–97 % RH, low hysteresis of 2.8 % RH, low response/recovery times of 14/49 s, high sensitivity of 862.19 kΩ/%RH, excellent long-time stability and repeatability, and good flexibility. In the future, the proposed sensor can be widely applied in human respiration monitoring, non-contact switch, and detection of volatile organic compounds.

A high-sensitivity and multi-response magnetic nanofiber-aerogel sensor with directionally aligned porous structure based on triple network for interactive human–machine interfaces

Flexible multimodal sensors with a porous structure have attracted tremendous attentions due to their low density, high specific surface area, a wide detection range and satisfied deformability. However, pores disorder and maldistribution issues of these multimodal sensors are major concerns during their sensing response, which often cause poor linearity and unstable sensing characteristics. Herein, a facile and rapid approach was proposed to fabricate a multifunctional magnetic sensor with directionally aligned porous structure based on triple network by combining electrospun nanofibers, bidisperse magnetic particles and sodium alginate/chitosan foam. The electrospun nanofibers were employed as three-dimensional skeletons for the crystallization and vertical growth of ice crystals. Benefiting from the remarkable structure orientation, the homogenized nanofiber-aerogel scaffold possesses excellent flexibility, superior deformation recoverability and biocompatibility. The assembled sensors not only exhibit a high sensitivity (0.40 T−1), rapid response/recovery time and long stability under magnetic stimuli, but also displays satisfied cross-sensitivity, quick response and reliable durability (8000 cycles) in response to external mechanical functions. Importantly, the respective input stimuli could be clearly discriminated via outputting the electrical signals of opposite or different trends. Furthermore, the sensor could be employed as wearable skins to monitor various physiological signals and realize information translation by Morse mode for individuals with disabilities. Additionally, a wearable gesture recognition system with assistance of the deep learning algorithm was testified, with high average recognition accuracy of 99 %. The simple fabrication process and prominent multifunctional characteristics of the proposed sensor endow it with an extensive application prospect in the field of interactive human–machine interfaces.

Excellent performance of Ag6Si2O7 oxidase mimic endowed by self-released ions for rapid colorimetric determination with reduced operational interference

Increasing attention has been directed towards oxidase mimics due to their catalytic ability toward enzyme substrates in the absence of H2O2, offering great colorimetric sensing potential in assays and diagnostics. However, slow electron-transfer and unstable absorbance over time often lead to unsatisfactory enzymatic reaction rates and unreliable readouts, significantly reducing detection efficiency and accuracy. Herein, we report on an Ag6Si2O7 nanozyme utilizing 3,3′,5,5′-tetramethylbenzidine (TMB) as a chromogenic substrate, demonstrating excellent oxidase-like activity and long-term stable colorimetric signals. Experimental results reveal that the excellent catalytic kinetics of Ag6Si2O7 (Km = 0.197 mM, Vmax = 5.1 × 10−7 M/s) are attributed to ultrafast electron transfer between Ag+ and TMB, mediated by Ag2O intermediates formed from self-released alkaline ions. Additionally, self-released H2SiO42− improves the stability of the oxidized substrate, resulting in a long-term stable colorimetric signal (∼20 min), which exhibits reliable accuracy regardless of the time point at which analyte is added within 20 min, thus eliminating the interference of individual operation time errors. Ascorbic acid (AA) is selected as the target molecule to assess the performance of the Ag6Si2O7-TMB colorimetric sensing system. This approach demonstrates a wide detection range from 5 to 300 μM and a detection limit of 0.452 μM. The developed colorimetric sensing strategy exhibits good stability, specificity, rapidity, and potential application in real sample detection.

Novel solution-gated transistor sensor-based SnO2 epitaxial thin films grown by pulsed laser deposition for nitrite detection.

A solution-gate controlled thin-film transistor with SnO2 epitaxial thin films (SnO2-SGTFT) is successfully utilized for highly sensitive detection of nitrite. The SnO2 films are deposited as channel materials on a c-plane sapphire (c-Al2O3) substrate through pulsed laser deposition (PLD), with superior crystal quality and out-of-plane atomic ordering. PtAu NPs/rGO nanocomposites are electrodeposited on agold electrode to function as a transistor gate to further enhance the nitrite catalytic performance of thedevice. The change in effective gate voltage due to the electrooxidation of nitrite on the gate electrode is the primary sensing mechanism of the device. Based on the inherent amplification effect of transistors, the superior electrical properties of SnO2, and the high electrocatalytic activity of PtAu NPs/rGO, the SnO2-SGTFT sensor has a low detection limit of 0.1nM and a wide linear detection range of 0.1nM ~ 50mM at VGS = 1.0V. Furthermore, the sensor has excellent characteristics such as rapid response time, selectivity, and stability. The practicability of the device has been confirmed by the quantitative detection of nitrite in natural lake water. SnO2 epitaxial films grown by PLD provide a simple and efficient way to fabricate nitrite SnO2-SGTFT sensors in environmental monitoring and food safety, among others. It also provides a reference for the construction of other high-performance thin-film transistor sensors.

Ultra-fast light repair, ultrasensitive, large strain detection range PDA@RGO/EVA composites fiber flexible strain sensor

The sensor fabricated from high-molecular polymer is soft, lightweight, and biocompatible; however, traditional high-molecular polymers suffer from viscoelasticity and poor cycle stability. To address these issues, it is essential to develop flexible matrix materials that can overcome viscoelasticity, ensuring high sensitivity and long-term use under large strains for next-generation wearable intelligent devices. In this study, ethylene-vinyl acetate (EVA) with a shape memory effect was utilized as the substrate for a flexible sensor，the shape memory effect of EVA can eliminate the residual strain generated by each long time of use to improve its service life. A polydopamine@reduced graphene oxide (PDA@RGO)/EVA fiber flexible strain sensor was fabricated through melt extrusion, swelling ultrasound, and in-situ polymerization techniques. The resulting sensor exhibits high sensitivity (gauge factor=1801.21), a wide strain detection range (strain = 193 %), and excellent stability and durability (2000 cycles). Notably, the PDA@RGO/EVA fiber flexible strain sensor demonstrates exceptional dual thermal and light repair functions, with light repair achieving a repair speed of 5 seconds, 100 % electrical performance repair efficiency, and perfect consistency in relative resistance response before and after repair. Furthermore, the PDA@RGO/EVA strain sensor can monitor finger and wrist movements in real-time with high accuracy, highlighting its significant potential application in the wearable technology field.

Integrating all-yarn-based triboelectric nanogenerator/supercapacitor for energy harvesting, storage and sensing

In the burgeoning field of energy harvesting, the integration and miniaturization of triboelectric nanogenerators with supercapacitors (TENG-SC) offers a promising frontier for developing self-powered wearable and portable sensing electronics. However, many TENG-SC systems encounter challenges in meeting wearability, high energy density, and ease of use requirements due to their complex configurations and limited flexibility. Herein, an asymmetric supercapacitor (ASC) was created by rolling up a lamellar multilayer film into a cylindrical yarn-based structure. The lamellar multilayer film comprises energy storage films with sequentially stacked layers of the positive AgNW/MnO2-TPU layer, PP separator layer, and negative AgNW/AC-TPU layer, tightly bonded to create a sandwich-like structure. The yarn-based ASC, functioning as an energy storage unit, demonstrates a high volumetric energy density of 3.2 mWh cm−3 and excellent cyclic stability (10000 cycles). Subsequently, a thinner sheath-core TPU/CB@AgNW/PMMA yarn was produced by combining wet spinning with electrospinning, which was helically wound around the yarn-based ASC to form an all-yarn-based TENG-ASC pressure-sensitive sensor that integrates energy harvesting, storage, and sensing. The miniaturized TENG-ASC yarn can convert various forms of bio-motion energy into electrical signals, with a maximum output voltage of around 3.5 V and a peak power density of 2.14 mW m−2. Simultaneously, this all-yarn-based TENG-ASC device achieves superior sensitivity (30.3 kPa−1) and has a wide pressure detection range of up to 50 kPa. This integrated system can continuously power electronic devices embedded in smart textiles, thereby extending their operational life and functionality.

Optical Label-Free Aptasensor Based on Weak Value Amplification for Real-Time and Ultrasensitive Detection of IgE.

Allergy is a prevalent disease, and the potential allergic population is expanding with industrialization and changes in people's living standards. Serum immunoglobulin E (IgE) level is one of the critical indicators for determining allergy. Here, we proposed a simple, real-time monitoring, low chip cost, label-free aptamer biosensing strategy based on weak value amplification (WVA) for the quantitative detection of IgE in serum samples, enabling early and accurate diagnosis of allergic or hypersensitive patients. The aptasensor combined an imaging weak measurement system with the high specificity of the aptamer for the marker IgE. By modifying the amino group at the 3-terminal end, the anti-IgE aptamers can attach to a dopamine-modified prism's surface and selectively recognize IgE in human serum. In the presence of IgE, a specific binding reaction occurred, resulting in a change in the refractive index of the reactive region's surface, manifested as a change in the light intensity of the camera acquired experimental images. As the concentration of IgE increased, the relative light intensity advanced sequentially. The WVA-aptasensing strategy achieved a wide detection range of 0.01 ng/mL to 2 μg/mL in phosphate buffered saline buffer, with the resolution as low as 4.3 pg/mL. IgE testing experiments in human serum have proved the feasibility of our methods in detecting complex samples. In addition, the method specifically recognized IgE without interference from other proteins. We believe that our proposed sensing strategy opens up new possibilities for ultrahigh sensitivity screening of IgE and can be expanded to detecting other biomolecules.

Gold-coated D-shaped photonic crystal fiber refractive index sensor with a wide detection range and large manufacturing tolerance

A D-shaped photonic crystal fiber refractive index (RI) sensor is designed, and its performance is analyzed using the finite element method (FEM). A gold film is coated on the D-shaped surface of the fiber as a plasmonic material for surface plasmon resonance sensing. The U-shaped arrangement of holes of the same size in the fiber structure enhances the coupling resonance between the core mode and the surface plasmon polariton mode. Numerical results show that the RI range of the sensor is 1.20–1.40, the maximum wavelength sensitivity is 16008.98 nm/RIU, and the detection width is up to 0.2 RIU. In addition, this study analyzes the manufacturing tolerance for the sizes of the air holes. The results show that the manufacturing tolerance for the three types of air holes is as high as 25%, 11.1%, and 10.2% when h is 40µm. These findings lay the foundation for the mass production of sensors. The above results indicate that the sensor has remarkable advantages such as enhanced sensitivity, wide measurement range, and exceptional manufacturing stability, and has promising applications in the fields of bio-detection, drug supply detection, and water pollution control.

Polyaniline-based bovine serum albumin imprinted electrochemical sensor for ultra-trace-level detection in clinical and food safety applications

Monitoring bovine serum albumin (BSA) at ultra-low levels is crucial for clinical and food safety applications, as it plays a significant role in identifying various health conditions and potential risks, necessitating fast, trace-level detection of BSA. This study proposes an approach to address these challenges by employing molecularly imprinted polymer (MIP) to develop an ultra-trace-level and cost-effective BSA sensing platform. The MIP electrochemical sensor was developed using polyaniline (PANI) combined with the protein crosslinker glutaraldehyde (GA) to optimize BSA surface imprinting in the MIP. As a result, the sensor achieves a sensitivity of 1.24 μA/log(pg/mL), with a picomolar detectable limit of 2.3 pg/mL (0.035 pM) and a wide detection range from 20 pg/mL to 200,000 pg/mL (0.303 pM to 3030 pM), making it suitable for clinical and food safety applications. Additionally, the study explores the interaction between an acidic surfactant protein eluent (acetic acid with sodium dodecyl sulfate, AcOH-SDS) and BSA vacant sites, enhancing recognition and re-binding. The PANI-based MIP sensor demonstrates initial feasibility and practicality in commercial milk and real human serum, opening avenues for early disease detection and ensuring food safety in BSA-related immune responses.