High-sensitivity Measurements Research Articles

Glycerophospholipid polyunsaturation modulates resveratrol action on biomimetic membranes

The phytoalexin resveratrol has received increasing attention for its potential to prevent oxidative damages in human organism. To shed further light on molecular mechanisms of its interaction with lipid membranes we study resveratrol influence on the organisation and mechanical properties of biomimetic lipid systems composed of synthetic phosphatidylcholines with mixed aliphatic chains and different degree of unsaturation at sn-2 position (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, POPC, and 1-palmitoyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine, PDPC). High-sensitivity isothermal titration calorimetric measurements reveal stronger spontaneous resveratrol association to polyunsaturated phosphatidylcholine bilayers compared to the monounsaturated ones resulting from hydrophobic interactions, conformational changes of the interacting species and desolvation of molecular surfaces. The latter is supported by the results from Laurdan spectroscopy of large unilamellar vesicles providing data on hydration at the glycerol backbones of glycerophospholipides. Higher degree of lipid order is reported for POPC membranes compared to PDPC. While resveratrol mostly enhances the hydration of PDPC membranes, increasing POPC dehydration is reported upon treatment with the polyphenol. Dehydration of the polyunsaturated lipid bilayers is measured only at the highest phytoalexin content studied (resveratrol/lipid 0.5 mol/mol) and is less pronounced than the effect reported for POPC membranes. The polyphenol effect on membrane mechanics is probed by thermal shape fluctuation analysis of quasispherical giant unilamellar vesicles. Markedly different trend of the bending elasticity with increasing resveratrol concentration is reported for the two types of phospholipid bilayers studied. POPC membranes become more rigid in the presence of resveratrol, whereas PDPC-containing bilayers exhibit softening at lower concentrations of the polyphenol followed by a slight growth without bilayer stiffening even at the highest resveratrol content explored. The new data on the structural organization and membrane properties of resveratrol-treated phosphatidylcholine membranes may underpin the development of future liposomal applications of the polyphenol in medicinal chemistry.

Robust high-order petal-mode laser with tunable topological charge pumped by an axicon-based annular beam

In this work, we demonstrate a watt-level laser producing high-order, petal-shaped output modes with tunable topological charge, by using an axicon-based divergent annular pump beam. The topological charge of the output beam could be varied in the range of 34–72 by adjusting the position of the Nd:YVO4 crystal relative to the focal plane of the pump beam. The highest order petal-mode beam generated from the system had a topological charge of 72 and a power of 1.3 W. The highest output power up to 2.1 W with a topological charge of 34 was achieved at an absorbed pump power of 5.8 W. The generated output modes were observed to be robust under power scaling and on propagation, with the same spatial profiles being maintained in the near- and far-fields. We anticipate that this system design may find use as a laser source in applications such as 3D optical trapping, fabrication of optical vortex arrays, optical communications, and high-sensitivity spatial measurement.

Study of the frequency characteristics of a tremor analysis system based on a capacitive proximity sensor

The technique of tremor control using a capacitive sensor to ensure high sensitivity and stability of measurement results requires the correct selection of operating parameters of the system. Study of the influence of operating parameters, selection of the optimal antenna design and frequency-setting elements in a system for analyzing tremor of the upper limbs based on a capacitive proximity sensor. The tremor sensor being developed is based on a rectangular pulse generator, the generation frequency of which depends on the capacitance. The dependence of the generation frequency on the distance between the antenna and the limb was studied for various values of capacitance and resistance of the resistor in the generator circuit. It is proposed to use a circuit without a capacitor in the frequency-setting RC circuit, which allows for the largest frequency increment and clearly detects tremor with both large and small amplitude. An experimental study of various antenna designs was carried out. It has been shown that when using a helical antenna, the maximum sensitivity of the sensor is observed with the smallest diameter, however, the use of a small diameter reduces the area of interaction between the electric field and the tissues of the human limb. The electromagnetic method is a promising method for digitizing tremor, allowing for rapid non-contact diagnostics. The experimental results obtained make it possible to justify the choice of optimal parameters for the tremor analysis system.

ZnOHF-ZnO nanomaterial-coated macro-bend fiber triethylamine gas sensor working at room temperature

This study presents a room temperature triethylamine (TEA) gas sensor based on the macro-bend fiber. The sensor achieves the rapid and high sensitivity measurement of TEA gas by coating the bending section of the optical fiber with ZnOHF-ZnO nanomaterial. The macro-bend fiber structure increases the penetration depth of the evanescent field transmitting along the no-core optical fiber (NCF), what allowing more light to leak into layer of the gas-sensitive material and thus enhancing the sensitivity to TEA gas. Different sensing probes were fabricated and compared for the coating layers with ZnOHF and ZnOHF-ZnO, respectively. The results showed that the sensitivity of the ZnOHF-ZnO coated sensor was 0.0044 dB/ppm, which was three times higher than that of the ZnOHF-coated sensor. Other sensing performance was experimentally demonstrated with a limit of detection (LOD) of 1 ppm, a response time of 16 s, and a recovery time of 18 s, enabling fast detection for TEA gas. Finally, the working mechanism has been explained. This macro-bend fiber-based TEA gas sensor has the advantages of small size, low operating temperature, fast response time, and good selectivity, making it suitable for the rapid identification and detection of TEA gas.

Sensitivity volume as figure-of-merit for maximizing data importance in electrical impedance tomography

Objective. Electrical impedance tomography (EIT) is a noninvasive imaging method whereby electrical measurements on the periphery of a heterogeneous conductor are inverted to map its internal conductivity. The EIT method proposed here aims to improve computational speed and noise tolerance by introducing sensitivity volume as a figure-of-merit for comparing EIT measurement protocols. Approach. Each measurement is shown to correspond to a sensitivity vector in model space, such that the set of measurements, in turn, corresponds to a set of vectors that subtend a sensitivity volume in model space. A maximal sensitivity volume identifies the measurement protocol with the greatest sensitivity and greatest mutual orthogonality. A distinguishability criterion is generalized to quantify the increased noise tolerance of high sensitivity measurements. Main result. The sensitivity volume method allows the model space dimension to be minimized to match that of the data space, and the data importance to be increased within an expanded space of measurements defined by an increased number of contacts. Significance. The reduction in model space dimension is shown to increase computational efficiency, accelerating tomographic inversion by several orders of magnitude, while the enhanced sensitivity tolerates higher noise levels up to several orders of magnitude larger than standard methods.

Quantitative, high-sensitivity measurement of liquid analytes using a smartphone compass

Smartphone ubiquity has led to rapid developments in portable diagnostics. While successful, such platforms are predominantly optics-based, using the smartphone camera as the sensing interface. By contrast, magnetics-based modalities exploiting the smartphone compass (magnetometer) remain unexplored, despite inherent advantages in optically opaque, scattering or auto-fluorescing samples. Here we report smartphone analyte sensing utilizing the built-in magnetometer for signal transduction via analyte-responsive magnetic-hydrogel composites. As these hydrogels dilate in response to targeted stimuli, they displace attached magnetic material relative to the phone’s magnetometer. Using a bilayer hydrogel geometry to amplify this motion allows for sensitive, optics-free, quantitative liquid-based analyte measurements that require neither any electronics nor power beyond that contained within the smartphone itself. We demonstrate this concept with glucose-specific and pH-responsive hydrogels, including glucose detection down to single-digit micromolar concentrations with potential for extension to nanomolar sensitivities. The platform is adaptable to numerous measurands, opening a path towards portable, inexpensive sensing of multiple analytes or biomarkers of interest.

High enrichment and sensitive measurement of oxytetracycline in tea drinks by thermosensitive magnetic molecular imprinting based magnetic solid phase extraction coupled with boron doped carbon dots

As a typical kind of new pollutants, there are still some challenges in the rapid detection of antibiotics. In this work, a sensitive fluorescent probe based on boron-doped carbon dots (B-CDs) in combination with thermo-responsive magnetic molecularly imprinted polymers (T-MMIPs) was constructed for the detection of oxytetracycline (OTC) in tea drinks. T-MMIPs were designed, fabricated and employed to enrich OTC at trace level from tea drinks, and B-CDs were utilized as the fluorescent probe to detect the concentration of OTC. The proposed method exhibited good linear relationship with OTC concentration from 0.2 to 60 μg L−1 and the limit of detection was 0.1 μg L−1. The established method has been successfully validated with tea beverages. Present work was the first attempt application of T-MMIPs in combination with CDs in detection of OTC, and demonstrated that the proposed method endowed the detection of OTC with high selectivity, sensitivity, reliability and wide application prospect, meanwhile offered a new strategy for the method establishment of rapid and sensitive detection of trace antibiotics in food and other matrices.

A novel capacitive sensor featuring surface microstructure and hydrogels for measuring full pressure with high-sensitivity

Compared with positive pressure measurement, which is widely used in many fields, negative pressure measurement is often ignored. However, realizing full pressure measurement, that is, positive and negative pressure measurement, with high sensitivity and wide measurement range, is one of the most urgent development directions and key challenges faced by flexible pressure sensors. To overcome this challenging problem, a highly sensitive full-pressure capacitive sensor with surface microstructure and hydrogels is introduced in this paper. The sensing mechanism of the sensor is implemented by detecting the capacitance change caused by the change in the contact area between the hydrogel and the electrode due to the internal and external pressure difference. The PVA/KOH basic gel material is used to resist shear deformation, and the uniform microstructure on the gel surface is achieved by the template method. How to maximize the sensitivity of positive and negative pressure measurements is discussed by carefully evaluating the design parameters of the sensor. The fabricated sensor has a wide measurement range (-100–250 kPa) with high sensitivity (S = 15.6 nF/kPa) in the negative pressure region and (S = 5.2 nF/kPa) in the positive pressure region. In addition, the sensor exhibits fast response, cycle stability, and low measurement limit, which further enhances its performance advantages. In order to validate the application potential of the sensor, the paper conducts experimental verification using the relationship between wind pressure measurement results and the angle of contact with the sensor, as well as the relationship between vehicle speed and wind pressure magnitude. The results show that the designed sensor has potential application prospects in full pressure measurement.

Functionalized sampling swabs array-based portable ATP bioluminescence sensor with on-site enrichment and high specificity for live Salmonella detection

Live food-borne pathogens, featured with rapid proliferative capacity and high pathogenicity, pose an emerging food safety and public health crisis. The high-sensitivity detection of pathogens is particularly imperative yet remains challenging. This work developed a functionalized nylon swab array with enhanced affinity for Salmonella typhimurium (S.T.) for high-specificity ATP bioluminescence-based S.T. detection. In brief, the nylon swabs (NyS) were turned to N-methylation nylon (NyS-OH) by reacting with formaldehyde, and NyS-OH were further converted to NyS-CA by reacting with carboxylic groups of citric acid (CA) and EDC/NHS solution, for altering the NyS surface energy to favor biomodification. The antibody-immobilized nylon swab (MNyS-Ab) was ready for S.T.-specific adsorption. Three prepared MNyS-Ab were installed on a stirrer to form an MNyS-Ab array, allowing for on-site enrichment of S.T. through absorptive extraction. The enriched S.T. was quantified by measuring the bioluminescence of ATP released from cell lysis utilizing a portable ATP bioluminescence sensor. The bioassay demonstrated a detectable range of 102–107 CFU mL−1 with a detection limit (LOD) of 8 CFU/mL within 35 min. The signal of single MNyS-Ab swabs was 500 times stronger than the direct detection of 106 CFU/mL S.T. The MNyS-Ab array exhibited a 100-fold increase in extraction level compared to a single MNyS. This combination of a portable bioluminescent sensor and modified nylon swab array offers a novel strategy for point-of-care testing of live S.T. strains. It holds promise for high-sensitivity measurements of other pathogens and viruses.

Mouthguard-Type Wearable Sensor for Monitoring Salivary Turbidity to Assess Oral Hygiene.

Salivary turbidity is a promising indicator for evaluating oral hygiene. This study proposed a wearable mouthguard-type sensor for continuous and unconstrained measurement of salivary turbidity. The sensor evaluated turbidity by measuring the light transmittance of saliva with an LED and a phototransistor sealed inside a double-layered mouthguard. The sensor was also embedded with a Bluetooth wireless module, enabling the wireless measurement of turbidity. The mouthguard materials (polyethylene terephthalate-glycol and ethylene-vinyl acetate) and the wavelength of the LED (405 nm) were experimentally determined to achieve high sensitivity in salivary turbidity measurement. The turbidity quantification characteristic of the proposed sensor was evaluated using a turbidity standard solution, and the sensor was capable of turbidity quantification over a wide dynamic range of 1-4000 FTU (formazine turbidity unit), including reported salivary turbidity (400-800 FTU). In vitro turbidity measurement using a saliva sample showed 553 FTU, which is equivalent to the same sample measured with a spectrophotometer (576 FTU). Moreover, in vivo experiments also showed results equivalent to that measured with a spectrophotometer, and wireless measurement of salivary turbidity was realized using the mouthguard-type sensor. Based on these results, the proposed mouthguard-type sensor has promising potential for the unconstrained continuous evaluation of oral hygiene.

Modeling and experimental studies of degaussing hysteresis in near-zero magnetic shielding systems

Near-zero magnetic shielding systems (MSSs) can provide basic experimental environments for extremely weak magnetic measurements. Reducing the internal magnetic field of MSS is the crucial element of high-sensitivity measurements, which is related to the shielding material flux. As an effective way to regulate the material remanence, degaussing reconstructs the magnetic balance with the geomagnetic field. However, previous research studies mainly focused on the optimization of material degaussing, with few considering the practical application scenarios of MSS. In this work, a numerical modeling method is proposed to realistically depict the balancing process, and the mapping relationship between the internal magnetic field of the MSS and the degaussing current is established. First, the magnetic field source analysis is carried out, and the internal magnetic field fluctuations of the MSS during degaussing are decomposed into multi-harmonic components. Then, the phase and amplitude changes of the hysteresis loop are simulated to predict the residual field. Thereafter, the effectiveness of the method is verified by a magnetic shielding cylinder. The experimental results indicate that the slight difference in material remanence has a negligible effect on the residual field. This work has potential application value in the research of degaussing technology.

High-sensitivity and high-speed measurements of ultrashort pulses as short as 74 fs at 1.9 µm using a GRENOUILLE device.

Ultrashort laser pulse sources in the wavelength range of 1.8 to 2 µm have many potential applications including medicine, materials processing, and sensing. In the use of such lasers, a crucial task is to measure their pulse's temporal intensity and phase. Such measurement devices are most useful when they are simple to build and operate and also have high speed and high sensitivity. The GRENOUILLE measurement device with few components, no moving parts, sensitivity of hundreds of picojoules, and measurement speed of hundreds of milliseconds, is commonly used to solve this problem at other wavelengths. In this paper, the measurement of ultrashort pulses by a GRENOUILLE device, developed using a silicon matrix sensor, for pulses in the wavelength range of 1.8 to 2 µm has been demonstrated. It is shown that ultrashort pulses with durations of 74 to 900 fs and a maximum spectral FWHM of 85 nm can be measured with this device. The recently developed ultra-reliable RANA approach was used for pulse retrieval from the measured traces. The device's performance was validated by comparing its measurements with those obtained by the robust FROG technique.

High enrichment and sensitive measurement of seventeen phthalates in beverages with metal organic framework functionalized magnetic MXene nanocomposite based on magnetic solid phase extraction prior to gas chromatography-triple quadrupole mass spectrometry

Phthalates (PAEs) are typical plasticizers, and widely used in various products. Because of their toxic effects such as carcinogenicity and endocrine disruption, they have become one of the most important public health hazards. It is vital to establish reliable methods for sensitively measuring PAEs at trace levels in the environment. In present study, a new magnetic metal organic framework functionalized MXene composite was designed (CoFe2O4@Ti3C2@MIL101(Cr)), in which NH2-MIL101(Cr) was successfully modified onto the surface of aldehyde-functionalized magnetic titanium carbide by Schiff base reaction. The prepared magnetic composite was used as the adsorbent for magnetic solid-phase extraction (MSPE) in combination with gas chromatography–triple quadrupole mass spectrometry (GC-MS/MS) for high-performance enrichment and sensitive measurement of seventeen PAEs. CoFe2O4@Ti3C2@MIL101(Cr) had favorable adsorption ability for PAEs, the adsorption of PAEs was multilayered and non-uniform, and followed the pseudo-second-order kinetic model and Redlich-Peterson isotherm model. Moreover, the results revealed that the lower temperature was more beneficial for the extraction of PAEs. The factors influencing the enrichment efficiencies of PAEs were investigated. Under the optimal experimental conditions, the constructed method exhibited prominent linearity over concentration range of 0.01–40 μg L−1, and the limits of detection (LODs) were very low over range of 0.003–0.018 μg L−1. The extraction efficiencies of seventeen PAEs were ranged from 44.2 % to 104 %. The established method was validated for determining PAEs in the different beverages, and DIBP (0.19 μg L−1) and DBP (0.44 μg L−1) were successfully detected in tea drinks, and the spiked recoveries of seventeen PAEs in real samples were in the range of 86.9 −100.2 %, with standard deviations less than 5.8 %. The enrichment factors were between 71 and 166. In short, the proposed method earned prominent sensitivity and high feasibility, and could be a credible, and valuable alternative for monitoring PAEs in the future.

High sensitivity strain measurement on a vibrating saxophone reed using stroboscopic digital image

In this paper, we present a study of different optical textures and techniques to apply very fine, non-specular reflecting random speckle texture, which makes it possible to measure surface strains with a sensitivity better than 0.01 % strain on a vibrating object. The method is based on triggered stroboscopic digital image correlation, which is able to obtain time-resolved full-field measurements of displacement and strain fields. The method is demonstrated on reeds of the saxophone to investigate their role in sound production and playability. Such high-sensitivity measurements allow the detection of subtle effects, such as artefacts on synthetic saxophone reeds caused by the production process.

Experimental study on a parallel optical fiber Sagnac loops-based sensor with the advantages of both high sensitivity and ultra-wide measurement range

The Vernier effect (VE) in optical interferometers has been used to improve the sensitivity in the measurements of strain, temperature, refractive index, etc. However, as the wavelength shifts beyond a free spectral range (FSR), it is difficult to determine the magnitude of the physical quantity and the measurement range is usually narrow. To overcome this problem, we constructed a fiber optic sensor combining two parallel Sagnac interferometers (PSIs) with a fiber Bragg grating (FBG). The sensitivity of temperature and strain measurements were enhanced about 5 times due to the VE effect in PSIs. FBG spectrum, which showed a monotonic and linear variation trend along with the variation of strain and temperature, was used to estimate the magnitude of the physical quantity beyond the FSR. Finally, an average strain sensitivity of −104.4 pm/µε was obtained in a wide measuring range of 0–5440 µε, while an average temperature sensitivity of 6.12 nm/°C was obtained in the temperature range of 2–58 °C. The measurement range has been extended 6 times and 4 times respectively compared to a single FSR. The integration of PSIs and FBG sensors offers not only high sensitivity, but also a wide measuring range. It can be used in many areas including medical equipment, automotive, and aerospace to make accurate strain and temperature measurements.

Pressure-insensitive magnetic shear force sensor with pillar structure for versatile application

A flexible shear force sensor, exhibiting pressure-insensitivity, high sensitivity, and bidirectional measurement capabilities, is developed using a slender and flexible planar hall magnetoresistive (PHMR) sensing element combined with a pillar structure. The pillar structure, placed atop the PHMR sensing element, minimizes the influence of normal force on the sensor, enhancing its shear force sensing ability. This sensor features a 2.5 mm diameter pillar structure and measures bidirectional shear forces within a dynamic range of -0.1 N to 0.1 N, with a resolution of 0.4 mN and a sensitivity of 10 mV/N. The vertical force sensitivity is 500 times smaller than the shear force sensitivity, ensuring precise shear force measurements. This design simplifies signal monitoring, enabling accurate and precise measurements. Our sensor exhibits exceptional repeatability and nonhysteresis in shear forces, affirming its stability and reliability. These characteristics establish its suitability for measuring water and air flow velocities and various experimental applications, including braille reading. This shear force sensor, showcased in our study, demonstrates consistent performance across diverse environments, indicating its potential for applications requiring precise control and detection, such as robotic fingers, medical devices, and wearable monitoring systems.

Simulation of Electrical Biofilm Impedance to Determine the Sensitivity of Electrode Geometries

Biofilms are ubiquitous at interfaces of natural and technical origin. Depending on type and application, biofilm formation is desired or has to be prevented. Therefore, reliable detection of initial biofilm growth is essential in many areas. One method of biofilm monitoring is the electrochemical impedance spectroscopy. Among other factors, this method is heavily dependent on the electrode geometry. In order to achieve a high measurement sensitivity, the electrode size must be chosen according to the biofilm that is to be measured. This paper presents an approach for simulating and modeling the optimal electrode geometry for a specific biofilm. First, a geometric model of a biofilm with up to 6000 individual bacteria is generated. The simulated impedances are used to calculate which electrode geometry maximizes sensitivity depending on the biofilm height. In the chosen example of an E. coli biofilm in a nutrient solution, the optimum size of an interdigital electrode (bar gap equals width) was 2.5 µm for a biofilm height of up to 2 µm. The used algorithms and models can be simply adapted for other biofilms. In this way, the most sensitive electrode geometry for a specific biofilm measurement can be determined with minimal effort.

Thermal imaging and computer vision technologies for the enhancement of pig husbandry: a review.

Pig farming, a vital industry, necessitates proactive measures for early disease detection and crush symptom monitoring to ensure optimum pig health and safety. This review explores advanced thermal sensing technologies and computer vision-based thermal imaging techniques employed for pig disease and piglet crush symptom monitoring on pig farms. Infrared thermography (IRT) is a non-invasive and efficient technology for measuring pig body temperature, providing advantages such as non-destructive, long-distance, and high-sensitivity measurements. Unlike traditional methods, IRT offers a quick and labor-saving approach to acquiring physiological data impacted by environmental temperature, crucial for understanding pig body physiology and metabolism. IRT aids in early disease detection, respiratory health monitoring, and evaluating vaccination effectiveness. Challenges include body surface emissivity variations affecting measurement accuracy. Thermal imaging and deep learning algorithms are used for pig behavior recognition, with the dorsal plane effective for stress detection. Remote health monitoring through thermal imaging, deep learning, and wearable devices facilitates non-invasive assessment of pig health, minimizing medication use. Integration of advanced sensors, thermal imaging, and deep learning shows potential for disease detection and improvement in pig farming, but challenges and ethical considerations must be addressed for successful implementation. This review summarizes the state-of-the-art technologies used in the pig farming industry, including computer vision algorithms such as object detection, image segmentation, and deep learning techniques. It also discusses the benefits and limitations of IRT technology, providing an overview of the current research field. This study provides valuable insights for researchers and farmers regarding IRT application in pig production, highlighting notable approaches and the latest research findings in this field.

High-frequency resolution diamond nitrogen-vacancy center wide-spectrum imaging technology

High-resolution wide-spectrum measurement techniques have important applications in fields such as astronomy, wireless communication, and medical imaging. Nitrogen-vacancy (NV) center in diamond is well known for its high stability, high sensitivity, real-time monitoring, single-point detection, and suitability for long-term measurement, and has an outstanding choice for spectrum analyzers. Currently, spectrum analyzers based on NV centers as detectors can perform real-time spectrum analysis in the range of several tens of gigahertz, but their frequency resolution is limited to a MHz level. In this study, we construct a quantum diamond microwave spectrum imaging system by combining continuous wave-mixing techniques. According to the spin-related properties of the NV center in diamond, we implement optical pumping by 532 nm green laser light illuminating the diamond NV center. A spherical magnet is used to produce a magnetic field gradient along the direction of the diamond crystal. By adjusting the size and direction of the magnetic field gradient, spatial encoding of the resonance frequency of the NV center is achieved. The magnetic field gradient induces the Zeeman effect on the diamond surface at different positions, generating corresponding ODMR signals. Through accurate programming, we coordinate the frequency scanning step size of the microwave source with the camera exposure and image storage time, and synchronize them circularly according to the order of image acquisition. Ultimately, after algorithmic processing, we successfully obtain comprehensive spectrum data in a range from 900 MHz to 6.0 GHz. Within the measurable spectrum range, the system employs continuous wave-mixing, simultaneously applying resonant microwaves and slightly detuning auxiliary microwaves to effectively excite the NV center. This method triggers off microwave interference effects, disrupting the balance between laser-induced polarization and microwave-induced spontaneous relaxation. Specifically, microwave interference causes the phase and amplitude of the fluorescence signal to change, leading to the generation of alternating current fluorescence signals. This further enhances the response of the NV magnetometer to weak microwave signals. The method enables the system to achieve a frequency resolution of 1 Hz in the measurable spectrum range, and it can separately measure the frequency resolution of multiple frequency points with a frequency step size of 1 MHz. The research results indicate that the wide-spectrum measurement based on NV centers can achieve sub-hertz frequency resolution, providing robust technical support for future spectrum analysis and applications.

Study of cryogenic temperature sensing based on an all-fiber Sagnac loop with high sensitivity and wide measurement range

Study of cryogenic temperature sensing based on an all-fiber Sagnac loop with high sensitivity and wide measurement range