Wenzhong Liu

• Doctor of Philosophy
• Chair at Huazhong University of Science and Technology

Magnetic nanoparticle (MNP) agglutination-based optomagnetic biosensing has been applied for rapid and sensitive detection of various biomolecules. However, the underlying physics of optomagnetic biosensing remains a hurdle, especially when the size of MNPs approaches the laser wavelength, i.e., the scattering enters the Mie regime. In this study,...

Heat flux is a physical quantity that characterises the strength of heat transfer per unit area. Heat transfer occurs with a temperature difference. Herein, a remote heat flux measurement method based on the thermomagnetic effect is proposed. Using Bloch’s law, Faraday’s law of electromagnetic induction, and Fourier’s law, a temperature measurement...

The use of magnetic nanothermometry faces challenges in noninvasive thermal monitoring during hyperthermia therapy due to the impact of the biological protein corona. Herein, we present an advanced magnetic nanothermometry model that incorporates the linear and cubic susceptibility phases, ensures robustness against hydrodynamic variations, maintai...

In this study, a novel human-size handheld magnetic particle imaging (MPI) system was developed for the high-precision detection of sentinel lymph nodes for breast cancer. The system consisted of a highly sensitive home-made MPI detection probe, a set of concentric coils pair for spatialization, a solenoid coil for uniform excitation at 8 kHz@1.5 m...

This paper presents a novel method for estimating the temperature of magnetic nanoparticles (MNPs) based on AC magnetization harmonics of MNPs dominated by Brownian relaxation. The disparity in the AC magnetization response and magnetization harmonic between the Fokker-Planck equation and the Langevin function was analyzed, and we studied the relat...

Magnetic nanoparticles (MNPs) are temperature sensitive, making them useful as probes for measuring cellular temperature. In this paper, we propose a remote non-invasive thermometer that replaces a traditional magnetic sensor with linearly polarized light as the transmission medium, utilizing the Faraday rotation of MNPs. This method not only overc...

Magnetic nanoparticle (MNP) has attracted interest in various research fields due to its special superparamagnetic and strong magneto-optical effects, especially as contrast agents to enhance the contrast of medical imaging. By introducing the interaction coefficient, we propose a model of the nonlinear Faraday rotation of MNP under the excitation...

In this Letter, we propose a thermometry method for magnetic nanoparticles in complex magnetic fields. Complex magnetic fields result in intricate magnetization that can be influenced by temperature and relaxation mechanisms. We derive a set of approximate equations from the results of a numerical simulation of the nonlinear dynamic magnetic respon...

In this paper, a new concept of magnetic nanoparticles (MNPs) as magneto-optical markers is proposed, and a “magneto-optical gate” effect is explored. High-sensitivity detection of MNPs was developed based on this principle. Under irradiation from monochromatic light with a wavelength much larger than the size of a given MNP, Rayleigh scattering oc...

The LWD-NMR instruments are limited by the telemetry bandwidth and logging timing requirements, so the echo T2 spectrum inversion function must be implemented at downhole logging instruments. Firstly, the inversion problem of T2 spectrum is converted to a non-negative least squares problem and solved by the accelerated projective gradient descent (...

In this paper, a new concept of magnetic nanoparticles as magneto-optical markers is proposed, and a "magneto-optical gate" effect is explored. High-sensitivity detection of magnetic nanoparticles (MNPs) was developed based on this principle. Under irradiation from monochromatic light with a wavelength much larger than the size of a given MNP, Rayl...

In this study, we demonstrate a novel magneto-optical (MO) thermometer using a MO Kerr effect (MOKE) system optimally configured with a photoelastic modulator (PEM) that combines the optical and pyro effects of Fe-Gd nanofilm to detect transient surface temperatures with high sensitivity and temporal resolution. The ac–dc harmonic ratio of the modu...

Spatial resolution is a key metric for characterizing magnetic particle imaging (MPI), and magnetic relaxation is a critical factor affecting the spatial resolution. This study investigates the point spread functions (PSFs) of MPI and analyzes the potential of breaking through the spatial resolution limit, which equals the full width at half maximu...

We present a new method for measuring the temperature of magnetic nanoparticles that can also be adapted to immobilized particles. The Néel relaxation mechanism, which dominates the dynamic magnetization process of immobilized magnetic nanoparticles, can be used as an intermediate parameter in a sensing model to obtain temperature information. In t...

Thermometry is essential in laboratory and industry settings. We propose a noninvasive temperature measurement method based on the superparamagnetic properties of nickel-plated films.When the nickel(Ni) film is uniformly heated from 100K to 300K, we observe that the polarization angle of the reflected polarized light decreases correspondingly. Comp...

Magnetic nanoparticles (MNPs) have significant temperature-to-magnetization transition effect at nanoscale. Yet temperature measurement based on MNPs is currently seriously interfered by their on-site concentration. By utilizing the electron paramagnetic resonance (EPR), we report a highly sensitive temperature measurement approach independent of c...

In this study, a real-time detection method for amol biomolecules based on second and third harmonics of water-based magnetic nanoparticles (MNPs) is reported. In previous magnetic immunoassay methods based on magnetic particle spectroscopy (MPS), the first harmonic was affected by the diamagnetic environment and would easily interfere with the sig...

Purpose To achieve simultaneous T1,w/proton density fat fraction (PDFF)/R2∗ mapping in abdomen within a single breadth‐hold, and validate the accuracy using state‐of‐art measurement. Theory and Methods An optimized multiple echo gradient echo (GRE) sequence with dual flip‐angle acquisition was used to realize simultaneous water T1 (T1,w)/PDFF/R2∗...

In the paper, the temperature dependence of magnetic nanoparticle (MNP) paramagnetic chemical shift (paraSHIFT) was studied by magnetic resonance (MR) spectroscopy. Based on it, iron oxide MNPs are considered as MR shifting probes for determining the temperature in liquids. With the increase in measurement temperature of the MNP reagent with MNPs,...

Magnetic nanoparticles (MNPs) have excellent magnetic-temperature characteristic. However, current temperature measurement based on MNPs is interfered by concentration. Utilizing the electron spin resonance (ESR), we propose a highly sensitive temperature measurement method without concentration coupling. The anisotropic field is affected by temper...

A new remote method for measuring temperature using magnetic nanoparticles (MNPs) is presented in this paper. The method involves exciting MNPs in a dual-frequency AC magnetic field, and using tunnel magnetoresistance to detect the mixing-frequency magnetization response signals. The effects of the excitation magnetic field amplitude and frequency...

Magnetic nanoparticles (MNPs) can work as temperature sensors to realize temperature measurement due to the excellent temperature sensitivity of their magnetization. This paper mainly reports on a performance optimization method of MNPs DC thermometry model. Firstly, by exploring the influencing factors of MNPs magnetization temperature sensitivity...

This study proposes a temperature model for the relaxation of magnetic nanoparticles and a phase measurement method under a mixing-frequency excitation field, which can improve the accuracy of temperature measurements in magnetic nanothermometry. According to the Debye-based magnetization model for magnetic nanoparticles, phases at mixing frequenci...

In this study, we proposed a temperature model of magnetic nanoparticle relaxation and a phase measurement method under a mixing-frequency excitation field, which can improve the temperature accuracy of magnetic nanothermometry. According to the Debye-based magnetization model for magnetic nanoparticles, the phases at the mixing frequencies are use...

This paper reports on a highly accurate approach of magnetic resonance (MR) thermometry using iron oxide magnetic nanoparticles (MNPs) as temperature sensors. An empirical model for the description of the temperature dependentR2relaxation rate is proposed by taking into account the temperature sensitivity of the MNP magnetization. The temperature s...

In this paper, the influences of signal bandwidth and phase delay on the spatial resolution of complex susceptibility based magnetic particle imaging (csMPI) are investigated by modeling the transfer function of the measurement circuit. Based on the simulation and experimental results, it is found that the signal bandwidth and the phase delay will...

Magnetic iron oxide nanoparticles are relatively advanced nanomaterials, and are widely used in biology, physics and medicine, especially as contrast agents for magnetic resonance imaging. Characterization of the properties of magnetic nanoparticles plays an important role in the application of magnetic particles. As a contrast agent, the relaxatio...

A method for remote measurement of the temperatures of metal containers using magnetic nanoparticles (MNPs) is described. A differential structure composed of three inductors with iron cores was used to counteract the effect of the magnetic permeabilities of metal and air on the inductance. The change in inductance caused by the change in the tempe...

Purpose To develop a method based on fat‐water transition region extraction (TREE) for robust fat‐water separation and quantification in challenging scenarios, including low signal‐to‐noise ratio (SNR), fast changing B0 field, and disjointed anatomies. Theory and Methods In TREE method, the phasor solutions of each pixel were categorized into fat‐...

There is much debate about whether the junction temperature or phosphor temperature is higher in white light-emitting diodes (LEDs). The main reason is that the junction and phosphor temperatures cannot be measured directly using traditional temperature measurement tools. In this study, a magnetic nanoparticle thermometer, a nondestructive and prec...

The magnetic transparency of biological tissue allows the magnetic nanoparticle (MNP) to be a promising functional sensor and contrast agent. The complex susceptibility of MNPs, strongly influenced by particle concentration, excitation magnetic field and their surrounding microenvironment, provides significant implications for biomedical applicatio...

In this paper, an improved temperature measuring model for fuel cell temperature measurement is proposed based on the existed nanothermometer model, which is regarded as traditional temperature measuring model. With more realistic cases taken into consideration, the results of the improved model are more practical and accurate compared with the tra...

In this study, we investigate the influence of size distribution of magnetic nanoparticles (MNPs) on the magnetic signal and mathematical model of ac magnetic nanothermometry (MNTM). Based on the Taylor expansion of the Langevin function, two novel and real-time temperature estimation models that consider the size distribution of MNPs are proposed....

Magnetic nanothermometry is of great promising in future biomedical and industrial applications. However, the diameters of the used thermosensitive materials, magnetic nanoparticles, are commonly nonuniform, which will impact the performance of the magnetic nanothermometry. To achieve future high performance magnetic nanothermometer, we study the i...

Automated visual inspection (AVI) attracts increasing interest in product quality control both academic and industrial communities, particularly on mass production processes, because product qualities of most types can be characterized with their corresponding surface visual attributes. However, many product images in AVI systems are comprised of s...

The topic of online product quality inspection (OPQI) with smart visual sensors is attracting increasing interest in both the academic and industrial communities on account of the natural connection between the visual appearance of products with their underlying qualities. Visual images captured from granulated products (GPs), e.g., cereal products...

In this study, we present a novel noninvasive and real-time magnetic nanothermometry (MNTM) using both odd and even harmonics of magnetic nanoparticles (MNPs) under low frequency (f = 117 Hz) ac and dc magnetic fields. Based on the first-order Langevin function, the mathematical models of weighted amplitude summation of odd and even harmonics of MN...

Instantaneous and noninvasive temperature measurements are important when laser thermotherapy or welding is performed. A noninvasive nanosecond-resolved magnetic nanoparticle (MNP) temperature measurement system is described in which a transient change in temperature causes an instantaneous change in the magnetic susceptibilities of the MNPs. These...

The effects of applied magnetic field on the accuracy of magnetic nanothermometry were investigated through simulation and experiments. The simulation showed that increasing the applied magnetic field improves the accuracy of temperature measurement. In the simulation, a series of first-order Langevin functions was constructed to calculate temperat...

Computer vision as a fast, low-cost, noncontact, and online monitoring technology has been an important tool to inspect product quality, particularly on a large-scale assembly production line. However, the current industrial vision system is far from satisfactory in the intelligent perception of complex grain images, comprising a large number of lo...

Grain image I for image statistical modeling by WD model. (PPTX)

Image statistical modeling resultsof Grain image I by WD model. (XLSX)

The effect of the nonlinear time-drift gain in the power amplifier on the instability in a magnetic nanothermometer was studied to allow a very stable magnetic nanotermometer to be designed, which was then used to measure the temperature of a light-emitting diode pn-junction. Experiments showed that the system response fluctuated by less than 0.04%...

This study reports on a new approach for remote nanothermometry with short response time (milliseconds) aiming to operate in liquid media using AC susceptibility components of a suspended magnetic nanoparticle subjected to the Brownian relaxation mechanism. A simple, low cost, and accurate system was designed to measure AC susceptibility using an A...

The precise measurement of temperature information is of great importance in the thermal management of light-emitting diodes (LEDs). Hitherto, many methods have been proposed to measure the LED temperature, but none of them involve with magnetics. Herein, we developed a noninvasive and precise method to probe the LED temperatures based on magnetic...

This paper reports on a new system of magnetic nanoparticle spectrometer to measure the magnetization spectrum of a magnetic nanoparticle based sample induced in alternating magnetic field with low frequency ( f = 192 Hz) for noninvasive magnetic nanothermometry. The achieved magnetic nanothermometer employs the measured fundamental and third harmo...

The signal transmission module of a magnetic nanoparticle thermometer (MNPT) was established in this study to analyze the error sources introduced during the signal flow in the hardware system. The underlying error sources that significantly affected the precision of the MNPT were determined through mathematical modeling and simulation. A transfer...

Magnetic nanoparticle temperature estimation by AC magnetization spectrum is a novel, precise and noninvasive temperature measurement approach [1-5] . Fluctuation of AC applied magnetic field is one of important impact factors that leading to temperature error. This study aims to evaluate the impact of the fluctuation of AC applied magnetic field u...

In recent years, a thermotherapy based on magnetic fluid nanomaterials can be used not only to generate heat, but also to deliver and release drugs in the process of treatment, even if the tissue tumors is deep [1]. Hence, the unique approach of magnetic fluid nanomaterials hyperthermia is becoming a promising treatment. However, the spread of nano...

Magnetic nanoparticle temperature estimation has been given both theoretical and experimental proving by using magnetic nanoparticle magnetization in DC and/or AC magnetic field [1-3]. However, the approaches assessing the average temperature of the target area are single point temperature estimation methods. And MPI has been presented to assess th...

Magnetic nanothermometry is a very promising technique, which has the potential for non-invasive and precise temperature probing in vivo[1-3]. Magnetic nanoparticle (MNP) magnetization induced in AC magnetic field is sensitive to temperature. In general, the harmonic of MNP magnetization is measured for temperature probing. Therefore, harmonic dist...

In this report, we study the relaxation measurement using optically detected magnetic resonance (ODMR) to detect cells that are coated with superparamagnetic nanoparticles. The emerging technology of ODMR represents a new detection method for magnetic relaxometry has reached sensitivity comparable to that of SQUIDs and without requiring cryogenics.

The noninvasive nanoscale thermometer with high measurement speed will become a very promising research. The speed of the temperature estimation using the model of AC magnetization spectrum is limited by the frequency of AC applied magnetic field [1-3]. You may need MHz magnetic field to get a faster temperature measuring or even higher frequency,...

In this paper, we study the computational modeling of electromagnetically induced heating in magnetic fluid hyperthermia. Owing to the Brownian rotation and Neel relaxation of induced magnetic moments, ferrofluids can generate heat when exposed to an alternating current magnetic field. To destroy all tumors cells while preventing deleterious physio...

In this study, we report on a new approach for remote temperature probing that provides accuracy as good as 0.017°C (0.0055% accuracy) by measuring the magnetisation curve of magnetic nanoparticles. We included here the theoretical model construction and the inverse calculation method, and explored the impact caused by the temperature dependence of...

In this study, we propose and demonstrate the usefulness of employing time-varying magnetization of a magnetic nanoparticle (MNP) based sample, induced by low frequency (f = 25 Hz) triangular-wave magnetic field, to achieve the approach of real-time recording of magnetization curve, which allows precise and noninvasive temperature probing with real...

This paper is focused on the signature of thermal-assisted cluster disruption while analyzing the inverse alternating current (AC) susceptibility (1/χ) versus temperature (T) curves recorded at lower AC frequencies (f), below 300 Hz. A commercial oil-based magnetic fluid (MF) sample was used in the experiments to investigate the critical temperatur...

The invention discloses a paramagnetism-based remote temperature measurement method for magnetic nanoparticles, and the method comprises: applying multiple times of excited magnetic fields on the area of a magnetic nano sample, constructing an equation group between the different excited magnetic fields and corresponding magnetic susceptibilities a...

This paper investigates a set of equations solving solution for magnetic nanoparticle temperature estimation. To achieve the temperature estimation using magnetic nanoparticles, a solution should be employed to solve the set of equations. And the solution to solve the set of equations is a key factor that affects the accuracy of temperature probing...

This paper aims to discuss a temperature measurement method based on the harmonic response of the magnetic nanoparticles by using AC magnetization. The simulation indicates that the harmonic response of magnetic nanoparticles in AC applied magnetic field has the potential of temperature probing. From the methods, we can find that the measurement ac...

This paper aims to design a system that can measure AC sample magnetization employing a pair of differentiating detection coils. A pair of Helmholtz coils generated the applied magnetic field. A new model and a pair of differentiating coils were used to reject the intrinsic residual of the applied magnetic field, which was caused by the mechanical...

This paper examines the advantages and disadvantages of noninvasive and remote temperature estimation employing magnetic nanoparticles (MNPs) in DC and AC applied fields. A Langevin function that describes the magnetization of the MNPs in different applied magnetic fields is investigated to obtain a noninvasive and remote measurement of on-site tem...

The influence of sample dilution upon cluster disruption/formation within a ferrofluid sample is investigated by monitoring the temperature dependence of the initial AC susceptibility. The effective magnetic response of the ferrofluid sample is described by a combination of Langevin’s functions modulated by the relative content of monomers and clus...

The low-field (below 5 Oe) ac and dc magnetic response of a magnetic fluid [MF] sample in the range of 305 to 360 K and 410 to 455 K was experimentally and theoretically investigated. We found a systematic deviation of Curie's law, which predicts a linear temperature dependence of inverse initial susceptibility in the range of our investigation. Th...

This study describes an approach for remote measuring of on-site temperature and particle concentration using magnetic nanoparticles (MNPs) via simulation and also experimentally. The sensor model indicates that under different applied magnetic fields, the magnetization equation of the MNPs can be discretized to give a higher-order nonlinear equati...

The method to determine the size distribution of nanosized ferrofluid by optimizing the discretization strategy used in calculations is demostrated in this paper. The discretization strategy is achieved with a modified optimal quantization theory to eventually reduce the ill-posed property of the magnetization numerical model. The optimization then...

This paper attempts to explore the effects of the different external fields on the inverse susceptibility-temperature curve. The superlinear property found in the inverse susceptibility-temperature curve of magnetic nanoparticle colloid solutions is assumed to be related to dimer disruption. The ac magnetic field accelerates cluster disruption, whe...

We herein describe several practical improvements to the method of obtaining the size distribution of magnetic nanoparticles (MNPs) using the magnetization curves obtained from a water-based MNP sample. A vibration sample magnetometer (VSM) was used in place of a superconducting quantum interference device (SQUID), to reduce MNP agglomeration and s...

In this paper, we proposed a laser welding quality monitoring system based on vector machine, which uses the light and sound sensors access to the various signals of the welding and Gabor transform features to extract the vector. The basic features of Laser welding is the formation of small holes, pool and photo-induced plasma, and the result is qu...

In this paper, we illustrate a method of reconstructing the size distribution of magnetic nano-particles (MNP) using a magnetization curve that was measured on a water-based MNP. The objective was to find solutions to the ill-posed problem in the matrix equation Ax=b, which was obtained from the numerical model on magnetization. Prior the use of Si...

Adequate penetration is a basic property of qualified welds. The proposed monitoring system was constructed to classify the welding state as adequate penetration or inadequate penetration by using infrared, ultraviolet and sound sensors. In order to achieve a smooth data acquisition and a quick response of the system, the circular buffer technology...

A study of minimum mutual information, which is treated as a criterion for the realizability of sensor-based systems, is presented. A model of mutual information transfer for gamma ray transmission measurement is established. Study of the mutual information obtained in the coalmine classification system shows that the system can be physically reali...

Solid particles will be charged when they are pneumatically conveyed in a pipe. The charged particles then cause the generation of electrostatic charges on the surface of a ring probe, which is a section of the transportation pipe and serves as a solid particle flow sensor. A series of experiments were carried out to study the characteristics of th...

In this paper, a significant effect producing systematic errors in the on-line measurement using gamma-ray transmission is revealed. Ash content fluctuations or thickness changes lead to a permanent negative systematic error in the results of the measurements. To study uncertainties in the measurements applicable to time-independent ash content ind...

This paper illustrates a method of reconstructing the size distribution of magnetic nano-particles (MNP) using a magnetization curve measured on a water-based MNP. To obtain the size distribution function, the solution of the integral equation describing fine particle magnetization in an external field must be found, without any a priori assumption...