Microwave-induced thermoacoustic imaging(MTAI)has advantages including the large imaging depth,high imaging resolution,high imaging contrast,and fast imaging speed.The thermoacoustic(TA)group of South China Normal Uni...Microwave-induced thermoacoustic imaging(MTAI)has advantages including the large imaging depth,high imaging resolution,high imaging contrast,and fast imaging speed.The thermoacoustic(TA)group of South China Normal University has dedicated to developing TA imaging for more than a decade and has made many breakthroughs.This review introduces these breakthroughs from two aspects including the improvement in techniques and the exploration of applications.On the technological level,there are ultrashort microwave pulse(USMP)-inducedTA imaging that can improve the imaging resolution,nonlinear thermoacoustic imaging(NTAI)that can improve the imaging contrast,polarized microwave-inducedthermoacoustic imaging(P-MTAI)that can obtain cellular-level alignment information,and more convenient and accurate handheld and multimodal probes.On the application side,the optimization and expansion have been carried out,mainly concentrating on breast and myocardial imaging.Finally,several current research directions are introduced,including the application of P-MTAI on joint imaging and research on whole-body imaging of small animals.展开更多
1.Challenges Thermoacoustic instability in combustors arises from the interaction between sound waves and unsteady heat release,commonly found in systems like gas turbines and aeroengines.This instability leads to und...1.Challenges Thermoacoustic instability in combustors arises from the interaction between sound waves and unsteady heat release,commonly found in systems like gas turbines and aeroengines.This instability leads to undesirable consequences such as structural damage and performance deterioration.The challenge lies in predicting and mitigating these instabilities due to the complex interplay of various physical phenomena like acoustic propagation,turbulent flow,and combustion chemistry,which are summarized in detail in Aimee S.Morgans and Dong Yang's published article.展开更多
Thermoacoustic instabilities,frequent in a wide range of combustors,arise from the intricate coupling between the flame's unsteady heat release and the combustor acoustic.The application of plasma,characterized by...Thermoacoustic instabilities,frequent in a wide range of combustors,arise from the intricate coupling between the flame's unsteady heat release and the combustor acoustic.The application of plasma,characterized by its substantial local energy addition and radical generation,has demonstrated potential in disrupting this coupling and thereby mitigating thermoacoustic oscillations.Notably,open-loop control using discharge plasma has been successfully implemented to suppress self-excited oscillations in a Rijke tube setup.Considering the broader context of a complex system that integrates both thermoacoustic systems and discharge plasma,experiments were done to see its performance in stability under different arrangement and discharge repetition rates of discharge plasma.These experimental investigations identified critical operating conditions essential for complete suppression:(A)the optimal location of discharge actuations,and(B)the minimum energy required for complete suppression.Moreover,the impact of discharge plasma,particularly when tuned to the eigenfrequencies of oscillations within the thermoacoustic system.was thoroughly examined.The insights gained from these successful suppression trials are instrumental in guiding the strategic design of both physical arrangement and electrical configurations for the control of combustion instabilities via discharge plasma.Furthermore,through the photographing of the swinging arcs and their thermal disturbances by high-speed camera and highspeed schlieren,the characteristics of arcs'thermal disturbances and the reasons affecting its suppression effectiveness were determined.展开更多
Thermoacoustic imaging(TAI)contrast comes from different electrical properties(EPs)of microwave absorption.However,the relationship between the permittivity distribution and the electric field polarization limits the ...Thermoacoustic imaging(TAI)contrast comes from different electrical properties(EPs)of microwave absorption.However,the relationship between the permittivity distribution and the electric field polarization limits the application of TAI in some extent.Here,we present a polarimetric thermoacoustic imaging(pTAI)system based on a rotary waveguide.By optimizing a rotary waveguide(insertion loss<0.2dB,return loss>15dB at 3GHz),the excitation wave emitted from a horn antenna can rotate freely in the direction of polarization.The multi-polarization pulsed microwave signal is used to evoke the thermoacoustic signals(TAS)of samples in different polarimetric directions.The simulation for pTAI with a multi-directional sample is first obtained.Then,we rotated the rotary waveguide at 10°/s and experimentally demonstrated the performance of pTAI by imaging three randomly placed soy sauce tubes and ex vivo beef.This study suggests that pTAI has potential for dielectric properties“diffusion”mapping,for example,provides conductivity tensor mapping of brain and muscle.展开更多
An acoustic pressure amplifier (APA) is capable of improving the match between a thermoacoustic engine and a load by elevating pressure ratio and acoustic power output. A standing-wave thermoacoustic engine driving a ...An acoustic pressure amplifier (APA) is capable of improving the match between a thermoacoustic engine and a load by elevating pressure ratio and acoustic power output. A standing-wave thermoacoustic engine driving a resistance- and-compliance (RC) load through an APA was simulated with linear thermoacoustics to study the impact of load impedance on the performance of the thermoacoustic system. Based on the simulation results, analysis focuses on the distribution of pressure amplitude and velocity amplitude in APA with an RC load of diverse acoustic resistances and compliance impedances. Variation of operating parameters, including pressure ratio, acoustic power, hot end temperature of stack, etc., versus impedance of the RC load is presented and analyzed according to the abovementioned distribution. A verifying experiment has been performed, which indicates that the simulation can roughly predict the system operation in the fundamental-frequency mode.展开更多
This paper proposes a loop-tube type thermoacoustic heating system without any moving parts based on the thermoacoustic effect. In a thermoacoustic heating system, the supplied sound is converted to heat and the heati...This paper proposes a loop-tube type thermoacoustic heating system without any moving parts based on the thermoacoustic effect. In a thermoacoustic heating system, the supplied sound is converted to heat and the heating point is heated. A thermoacoustic heating system differs from a thermoacoustic cooling system： The location of the reference temperature section at the heat pump is upside down. The authors construct a prototype ofthermoacoustic heating system. The experimental results show that the heating point reaches 100 ~C. It must be emphasized that, using this simple and inexpensive thermoacoustic heating system, noise, waste heat and unused heat are useful as a renewable energy source.展开更多
Microwave induced thermoacoustic imaging(MTAI)has emerged as a potential biomedical imaging modality with over 20-year growth.MTAI typically employs pulsed microwave as the pumping source,and detects the microwave-ind...Microwave induced thermoacoustic imaging(MTAI)has emerged as a potential biomedical imaging modality with over 20-year growth.MTAI typically employs pulsed microwave as the pumping source,and detects the microwave-induced ultrasound wave via acoustic transducers.Therefore,it features high acoustic resolution,rich elect romagnetic contrast,and large imaging depth.Benefiting from these unique advantages,MTAI has been extensively applied to various fields including pathology,biology,material and medicine.Till now,MTAI has been deployed for a wide range of biomedical applications,including cancer diagnosis,joint evaluation,brain in-vestigation and endoscopy.This paper provides a comprehensive review on(1)essential physics(endogenous/exogenous contrast mechanisms,penetration depth and resolution),(2)hardware configurations and software implementations(excit ation source,antenna,ultrasound detector and image recovery algorithm),(3)animal studies and clinical applications,and(4)future directions.展开更多
A model of quantum thermoacoustic refrigeration micro-cycle(QTARMC)is established in which heat leakage is considered.A single particle contained in a one-dimensional harmonic potential well is studied,and the system ...A model of quantum thermoacoustic refrigeration micro-cycle(QTARMC)is established in which heat leakage is considered.A single particle contained in a one-dimensional harmonic potential well is studied,and the system consists of countless replicas.Each particle is confined in its own potential well,whose occupation probabilities can be expressed by the thermal equilibrium Gibbs distributions.Based on the Schrodinger equation,the expressions of coefficient of performance(COP)and cooling rate for the refrigerator are obtained.Effects of heat leakage on the optimal performance are discussed.The optimal performance region of the refrigeration cycle is obtained by the using ofΩobjective function.The results obtained can enrich the thermoacoustic theory and expand the application of quantum thermodynamics.展开更多
This paper focuses on the temperature and pressure characteristics of a Swift-Backhaus type traveling-wave thermoacoustic prime mover during its onset and damping processes,in order to understand the intrinsic mechani...This paper focuses on the temperature and pressure characteristics of a Swift-Backhaus type traveling-wave thermoacoustic prime mover during its onset and damping processes,in order to understand the intrinsic mechanism of thermoacoustic oscillation onset and the feasibility of using low-grade thermal energy based on a low onset temperature. The influences of heat input and filling pressure on hysteretic loop,due to the noncoincidence between onset and damping processes,are measured and analyzed. The condition for the occurrence of hysteresis is also briefly discussed.展开更多
Here,we report a new method using combined magnetic resonance(MR)-Photoacoustic(PA)-Thermoacoustic(TA)imaging techmiques,and demonstrate its unique ability for in vrivo cancer detection using tumor-bearing mice.Circul...Here,we report a new method using combined magnetic resonance(MR)-Photoacoustic(PA)-Thermoacoustic(TA)imaging techmiques,and demonstrate its unique ability for in vrivo cancer detection using tumor-bearing mice.Circular scanning TA and PA imaging systems were used to recover the dielectric and optical property dist ributions of three colon carcinoma bearing mice While a 7.0-T magnetic resonance imaging(MRI)unit with a mouse body volume coil was utilized for high resolution structural imaging of the same mice.Three plastic tubes flled with soybean sauce were used as fiducial markers for the co-registration of MR,PA and TA images.The resulting fused images provided both enhanced tumor margin and contrast relative to the surrounding normal tissues.In particular,some finger-like protrusions extending into the surrounding tissues were revealed in the MR/TA infused images.These results show that the tissue functional optical and dielectric properties provided by PA and TA images along with the anatomical structure by MRI in one picture make accurate tumor identification easier.This combined MR-PA-TA-imaging strategy has the potential to offer a dinically useful triple-modality tool for accurate cancer detection and for intraoper ative surgical navigation.展开更多
Microwave-induced thermoacoustic imaging(TAI)is a noninvasive modality based on the differences in microwave absorption of various biological tissues.TAI has been extensively researched in recent years,and several stu...Microwave-induced thermoacoustic imaging(TAI)is a noninvasive modality based on the differences in microwave absorption of various biological tissues.TAI has been extensively researched in recent years,and several studies have revealed that TAI possesses advantages such as high resolution,high contrast,high imaging depth and fast imaging speed.In this paper,we reviewed the development of the TAI technique,its excitation source,data acquisition system and biomedical applications.It is believed that TAI has great potential applications in biomedical research and clinical study.展开更多
We present for the¯rst time in vivo imaging of rat brain using microwave-induced thermoacoustic tomography(TAT).The in vivo imaging of rat brain was realized through an unconventional delivery of microwave energy...We present for the¯rst time in vivo imaging of rat brain using microwave-induced thermoacoustic tomography(TAT).The in vivo imaging of rat brain was realized through an unconventional delivery of microwave energy from the front of rat brain(while the transducer was scanned along coronal plane of the animal brain),which maximized the microwave penetration into the brain.In addition,we found that the imaging contrast was highly dependent on the direction of the electric¯eld polarization(EFP)and that more tissue structures/compositions could be revealed when both X-and Y-EFPs were used for TAT.The in vivo TAT images of rat brain obtained were compared with the 3.0 T MRI images and histological photographs,and numerous important brain anatomical structures were identi¯ed.An example of our TAT approach for imaging a foreign object embedded in a rat brain was also demonstrated.This study suggests that TAT has a great potential to be used in neuroscience studies and in noninvasive imaging of brain disorders.展开更多
Microwave-induced thermoacoustic imaging(MI-TAI)remains one of the focus of attention among biomedical imaging modalities over the last decade.However,the transmission and dis-tribution of microwave inside bio-tissues...Microwave-induced thermoacoustic imaging(MI-TAI)remains one of the focus of attention among biomedical imaging modalities over the last decade.However,the transmission and dis-tribution of microwave inside bio-tissues are complicated,thus result in severe artifacts.In this study,to reveal the underlying mechanisms of artifacts,we deeply investigate the distribution of specific absorption rate(SAR)inside tissue-mimicking phantoms with varied morphological features using both mathematical simulations and corresponding experiments.Our simulated results,which are confirmed by the associated experimental results,show that the SAR distri-bution highly depends on the geometries of the imaging targets and the polarizing features of the microwave.In addition,we propose the potential mechanisms including Mie-scattering,Fabry-Perot-feature,small curvature effect to interpret the diffraction effect in different scenarios,which may provide basic guidance to predict and distinguish the artifacts for TAI in both fundamental and clinical studies.展开更多
A miniature thermoacoustic prime mover, consuming heat to radiate sound, may be considered as a potential way of heat management in microcircuits because of its simplicity and stability. A prototype with variable reso...A miniature thermoacoustic prime mover, consuming heat to radiate sound, may be considered as a potential way of heat management in microcircuits because of its simplicity and stability. A prototype with variable resonant tube length of 10 to 25 cm was built, and experiments were carried out to observe its performance, such as onset temperature, oscillation amplitude and operating frequency. The results with atmospheric air showed that proper structures and operating conditions can make the system start an oscillation at a temperature lower than 100 ℃, which proves the feasibility of potential usage in electronic units. The influences of stack position, heat input power or tube inclination on the oscillation amplitude, onset temperature and operating frequency are also presented.展开更多
Microwave-induced thermoacoustic tomography(TAT)is a rapidly-developing noninvasive imaging technique that integrates the advantages of microwave imaging and ultrasound imaging.While an image reconstruction algorithm ...Microwave-induced thermoacoustic tomography(TAT)is a rapidly-developing noninvasive imaging technique that integrates the advantages of microwave imaging and ultrasound imaging.While an image reconstruction algorithm is critical for the TAT,current reconstruction methods often creates significant artifacts and are computationally costly.In this work,we propose a deep learning-based end-to-end image reconstruction method to achieve the direct reconstruction from the sinogram data to the initial pressure density image.We design a new network architecture TAT-Net to transfer the sinogram domain to the image domain with high accuracy.For the scenarios where realistic training data are scarce or unavailable,we use the finite element method(FEM)to generate synthetic data where the domain gap between the synthetic and realistic data is resolved through the signal processing method.The TAT-Net trained with synthetic data is evaluated through both simulations and phantom experiments and achieves competitive performance in artifact removal and robustness.Compared with other state-of-the-art reconstruction methods,the TAT-Net method can reduce the root mean square error to 0.0143,and increase the structure similarity and peak signal-to-noise ratio to 0.988 and 38.64,respectively.The results obtained indicate that the TAT-Net has great potential applications in improving image reconstruction quality and fast quantitative reconstruction.展开更多
Microwave-induced thermoacoustic imaging(MTI)has the advantages of high resolution,high contrast,non-ionization,and non-invasive.Recently,MTI was used in the¯eld of breast cancer screening.In this paper,based on ...Microwave-induced thermoacoustic imaging(MTI)has the advantages of high resolution,high contrast,non-ionization,and non-invasive.Recently,MTI was used in the¯eld of breast cancer screening.In this paper,based on the¯nite element method(FEM)and COMSOL Multiphysics software,a three-dimensional breast cancer model suitable for exploring the MTI process is proposed to investigate the in°uence of Young's modulus(YM)of breast cancer tissue on MTI.It is found that the process of electromagnetic heating and initial pressure generation of the entire breast tissue is earlier in time than the thermal expansion process.Besides,compared with normal breast tissue,tumor tissue has a greater temperature rise,displacement,and pressure rise.In particular,YM of the tumor is related to the speed of thermal expansion.In particular,the larger the YM of the tumor is,the higher the heating and contraction frequency is,and the greater the maximum pressure is.Di®erent Young's moduli correspond to di®erent thermoacoustic signal spectra.In MTI,this study can be used to judge di®erent degrees of breast cancer based on elastic imaging.In addition,this study is helpful in exploring the possibility of microwave-induced thermoacoustic elastic imaging(MTAE).展开更多
A microwave-induced thermoacoustic imaging(MITAT)system is a non-destructive physical medical imaging method that combines the advantages of the high contrast of microwave imaging and the high resolution of ultrasound...A microwave-induced thermoacoustic imaging(MITAT)system is a non-destructive physical medical imaging method that combines the advantages of the high contrast of microwave imaging and the high resolution of ultrasound imaging.It uses the microwave as the excitation source and ultrasound as the information carrier.When different kinds of biological tissue absorb electromagnetic energy,it results in localized temperature rises.The thermal expansion will induce ultrasonic signals(i.e.,thermoacoustic signals),known as the thermoacoustic effect.The microwave absorption image of the sample can be reconstructed by algorithm processing.The MITAT contrast depends on different dielectric parameters of different kinds of tissue.We introduce the developed system and its application.In addition,the challenges and prospects of MITAT for further development are discussed.展开更多
Thermoacoustic imaging(TAI)is an emerging high-resolution and high-contrast imaging technology.In recent years,metal wires have been used in TAI experiments to quantitatively evaluate the spatial resolution of differe...Thermoacoustic imaging(TAI)is an emerging high-resolution and high-contrast imaging technology.In recent years,metal wires have been used in TAI experiments to quantitatively evaluate the spatial resolution of different systems.However,there is still a lack of analysis of the response characteristics and principles of metal wires in TAI.Through theoretical and simulation analyses,this paper proposes that the response of metal(copper)wires during TAI is equivalent to the response of antennas.More critically,the response of the copper wire is equivalent to the response of a half-wave dipole antenna.When its length is close to half the wavelength of the incident electromagnetic wave,it obtains the best response.In simulation,when the microwave excitation frequencies are 1.3 GHz,3.0 GHz,and 5.3 GHz,and the lengths of copper wires are separately set to 11 cm,5 cm,and 2.5 cm,the maximum SAR distribution and energy coupling effciency are obtained.This result is connected with the best response of half-wave dipole antennas with lengths of 11 cm,4.77 cm,and 2.7 cm under the theoretical design,respectively.Regarding the further application,TAI can be used to conduct guided minimally invasive surgery on surgical instrument imaging.Thus,this paper indicated that results can also guide the design of metal surgical instruments utilized in different microwave frequencies.展开更多
The microwave-induced thermoacoustic imaging(TAI)technology has both the advantages of high contrast of microwave imaging and high resolution of ultrasound imaging(UI),so it has carried out exploratory application res...The microwave-induced thermoacoustic imaging(TAI)technology has both the advantages of high contrast of microwave imaging and high resolution of ultrasound imaging(UI),so it has carried out exploratory application research in various areas,such as the early detection of breast tumors and cerebrovascular diseases.However,the microwave generator used in the traditional TAI technology is huge and expensive,and the temporal resolution is also too low due to the single-element scanning mechanism.Thus,it is difficult to meet the needs of clinical applications.In this paper,the iterative process and the analysis of related application scenarios from single-element scanning to portable and array-based TAI,such as the miniaturized microwave generator,handheld antenna,multi-channel data acquisition,and UI/TAIdual-modality imaging,are reviewed,and the future trends of this technology are discussed.This review helps researchers in the field of TAI learn the technological development process and future trends.It also deepens clinicians’understanding of TAI so as to put forward more application requirements.展开更多
As an emerging hybrid imaging modality,microwave-induced thermoacoustic imaging(MTAI),using microwaves as the excitation source and ultrasonic signals as the information carrier for combining the characteristics of hi...As an emerging hybrid imaging modality,microwave-induced thermoacoustic imaging(MTAI),using microwaves as the excitation source and ultrasonic signals as the information carrier for combining the characteristics of high contrast of electromagnetic imaging and high resolution of ultrasound imaging,has shown broad prospects in biomedical and clinical applications.The imaging contrast depends on the microwave-absorption coe±cient of the endogenous imaged tissue and the injected MTAI contrast agents.With systemically introduced functional nanoparticles,MTAI contrast and sensitivity can be further improved,and enables visualization of biological processes in vivo.In recent years,functional nanoparticles for MTAI have been developed to improve the performance and application range of MTAI in biomedical applications.This paper reviews the recent progress of functional nanoparticles for MTAI and their biomedical applications.The challenges and future directions of microwave thermoacoustic imaging with functional nanoparticles in theeld of translational medicine are discussed.展开更多
文摘Microwave-induced thermoacoustic imaging(MTAI)has advantages including the large imaging depth,high imaging resolution,high imaging contrast,and fast imaging speed.The thermoacoustic(TA)group of South China Normal University has dedicated to developing TA imaging for more than a decade and has made many breakthroughs.This review introduces these breakthroughs from two aspects including the improvement in techniques and the exploration of applications.On the technological level,there are ultrashort microwave pulse(USMP)-inducedTA imaging that can improve the imaging resolution,nonlinear thermoacoustic imaging(NTAI)that can improve the imaging contrast,polarized microwave-inducedthermoacoustic imaging(P-MTAI)that can obtain cellular-level alignment information,and more convenient and accurate handheld and multimodal probes.On the application side,the optimization and expansion have been carried out,mainly concentrating on breast and myocardial imaging.Finally,several current research directions are introduced,including the application of P-MTAI on joint imaging and research on whole-body imaging of small animals.
文摘1.Challenges Thermoacoustic instability in combustors arises from the interaction between sound waves and unsteady heat release,commonly found in systems like gas turbines and aeroengines.This instability leads to undesirable consequences such as structural damage and performance deterioration.The challenge lies in predicting and mitigating these instabilities due to the complex interplay of various physical phenomena like acoustic propagation,turbulent flow,and combustion chemistry,which are summarized in detail in Aimee S.Morgans and Dong Yang's published article.
基金supported by the Fundamental Research Funds for the Central Universities,China(No.501XTCX2023146001).
文摘Thermoacoustic instabilities,frequent in a wide range of combustors,arise from the intricate coupling between the flame's unsteady heat release and the combustor acoustic.The application of plasma,characterized by its substantial local energy addition and radical generation,has demonstrated potential in disrupting this coupling and thereby mitigating thermoacoustic oscillations.Notably,open-loop control using discharge plasma has been successfully implemented to suppress self-excited oscillations in a Rijke tube setup.Considering the broader context of a complex system that integrates both thermoacoustic systems and discharge plasma,experiments were done to see its performance in stability under different arrangement and discharge repetition rates of discharge plasma.These experimental investigations identified critical operating conditions essential for complete suppression:(A)the optimal location of discharge actuations,and(B)the minimum energy required for complete suppression.Moreover,the impact of discharge plasma,particularly when tuned to the eigenfrequencies of oscillations within the thermoacoustic system.was thoroughly examined.The insights gained from these successful suppression trials are instrumental in guiding the strategic design of both physical arrangement and electrical configurations for the control of combustion instabilities via discharge plasma.Furthermore,through the photographing of the swinging arcs and their thermal disturbances by high-speed camera and highspeed schlieren,the characteristics of arcs'thermal disturbances and the reasons affecting its suppression effectiveness were determined.
基金supported in part by the National Natural Science Foundation of China(No.82071940)the National Key R&D Program of China(No.2018YFF01013603)。
文摘Thermoacoustic imaging(TAI)contrast comes from different electrical properties(EPs)of microwave absorption.However,the relationship between the permittivity distribution and the electric field polarization limits the application of TAI in some extent.Here,we present a polarimetric thermoacoustic imaging(pTAI)system based on a rotary waveguide.By optimizing a rotary waveguide(insertion loss<0.2dB,return loss>15dB at 3GHz),the excitation wave emitted from a horn antenna can rotate freely in the direction of polarization.The multi-polarization pulsed microwave signal is used to evoke the thermoacoustic signals(TAS)of samples in different polarimetric directions.The simulation for pTAI with a multi-directional sample is first obtained.Then,we rotated the rotary waveguide at 10°/s and experimentally demonstrated the performance of pTAI by imaging three randomly placed soy sauce tubes and ex vivo beef.This study suggests that pTAI has potential for dielectric properties“diffusion”mapping,for example,provides conductivity tensor mapping of brain and muscle.
基金Project supported by the National Natural Sciences Foundation of China (No. 50536040)the University Doctoral Subject Special Foundation of China (No. 20050335047)+1 种基金the Postdoctoral Science Foundation of Zhejiang Province (No. 2006-bsh-21)the Natural Science Foundation of Zhejiang Province (No. Y107229), China
文摘An acoustic pressure amplifier (APA) is capable of improving the match between a thermoacoustic engine and a load by elevating pressure ratio and acoustic power output. A standing-wave thermoacoustic engine driving a resistance- and-compliance (RC) load through an APA was simulated with linear thermoacoustics to study the impact of load impedance on the performance of the thermoacoustic system. Based on the simulation results, analysis focuses on the distribution of pressure amplitude and velocity amplitude in APA with an RC load of diverse acoustic resistances and compliance impedances. Variation of operating parameters, including pressure ratio, acoustic power, hot end temperature of stack, etc., versus impedance of the RC load is presented and analyzed according to the abovementioned distribution. A verifying experiment has been performed, which indicates that the simulation can roughly predict the system operation in the fundamental-frequency mode.
文摘This paper proposes a loop-tube type thermoacoustic heating system without any moving parts based on the thermoacoustic effect. In a thermoacoustic heating system, the supplied sound is converted to heat and the heating point is heated. A thermoacoustic heating system differs from a thermoacoustic cooling system： The location of the reference temperature section at the heat pump is upside down. The authors construct a prototype ofthermoacoustic heating system. The experimental results show that the heating point reaches 100 ~C. It must be emphasized that, using this simple and inexpensive thermoacoustic heating system, noise, waste heat and unused heat are useful as a renewable energy source.
基金This work was supported in part by the National Natural Science Foundation of China(62022037,62105140,61775028,81571722 and 61528401)in part by Department of Science and Technology of Guangdong Province(2019ZT08Y191,SZBL2020090501013)+3 种基金Guangdong Provincial Key Laboratory of Advanced Biomaterials(2022B1212010003)Guangdong Provincial Department of Education(2021ZDZX1064)Shenzhen Science and Technology Program(JCYJ20200109141222892,KQTD20190-929172743294)in part by Startup grant from Southern University of Science and Technology.
文摘Microwave induced thermoacoustic imaging(MTAI)has emerged as a potential biomedical imaging modality with over 20-year growth.MTAI typically employs pulsed microwave as the pumping source,and detects the microwave-induced ultrasound wave via acoustic transducers.Therefore,it features high acoustic resolution,rich elect romagnetic contrast,and large imaging depth.Benefiting from these unique advantages,MTAI has been extensively applied to various fields including pathology,biology,material and medicine.Till now,MTAI has been deployed for a wide range of biomedical applications,including cancer diagnosis,joint evaluation,brain in-vestigation and endoscopy.This paper provides a comprehensive review on(1)essential physics(endogenous/exogenous contrast mechanisms,penetration depth and resolution),(2)hardware configurations and software implementations(excit ation source,antenna,ultrasound detector and image recovery algorithm),(3)animal studies and clinical applications,and(4)future directions.
基金Project(51176143)supported by the National Natural Science Foundation of ChinaProject(K201919)supported by the Scientific Research Foundation of Wuhan Institute of TechnologyChina。
文摘A model of quantum thermoacoustic refrigeration micro-cycle(QTARMC)is established in which heat leakage is considered.A single particle contained in a one-dimensional harmonic potential well is studied,and the system consists of countless replicas.Each particle is confined in its own potential well,whose occupation probabilities can be expressed by the thermal equilibrium Gibbs distributions.Based on the Schrodinger equation,the expressions of coefficient of performance(COP)and cooling rate for the refrigerator are obtained.Effects of heat leakage on the optimal performance are discussed.The optimal performance region of the refrigeration cycle is obtained by the using ofΩobjective function.The results obtained can enrich the thermoacoustic theory and expand the application of quantum thermodynamics.
基金the National Natural Science Foundation of China (Nos. 50776075 and 50536040)the Natural ScienceFoundation of Zhejiang Province (No. Y107229), China
文摘This paper focuses on the temperature and pressure characteristics of a Swift-Backhaus type traveling-wave thermoacoustic prime mover during its onset and damping processes,in order to understand the intrinsic mechanism of thermoacoustic oscillation onset and the feasibility of using low-grade thermal energy based on a low onset temperature. The influences of heat input and filling pressure on hysteretic loop,due to the noncoincidence between onset and damping processes,are measured and analyzed. The condition for the occurrence of hysteresis is also briefly discussed.
基金supported by the Chinese Govern-ment's 1000-Talent Plan via the University of Elec-tronic Science and Technology of China and by the J.Crayton Pruitt Family Endowment(to HJ)the National Natural Science Foundation of China(81130027 and 81520108014)+1 种基金the National"Twelfth FiveYear"Plan for Science&Technology Support(2012BAI23B08)the National Basic Research Program of China(973 Program,2011CB935800)(to FG).
文摘Here,we report a new method using combined magnetic resonance(MR)-Photoacoustic(PA)-Thermoacoustic(TA)imaging techmiques,and demonstrate its unique ability for in vrivo cancer detection using tumor-bearing mice.Circular scanning TA and PA imaging systems were used to recover the dielectric and optical property dist ributions of three colon carcinoma bearing mice While a 7.0-T magnetic resonance imaging(MRI)unit with a mouse body volume coil was utilized for high resolution structural imaging of the same mice.Three plastic tubes flled with soybean sauce were used as fiducial markers for the co-registration of MR,PA and TA images.The resulting fused images provided both enhanced tumor margin and contrast relative to the surrounding normal tissues.In particular,some finger-like protrusions extending into the surrounding tissues were revealed in the MR/TA infused images.These results show that the tissue functional optical and dielectric properties provided by PA and TA images along with the anatomical structure by MRI in one picture make accurate tumor identification easier.This combined MR-PA-TA-imaging strategy has the potential to offer a dinically useful triple-modality tool for accurate cancer detection and for intraoper ative surgical navigation.
基金the National Natural Science Foundation of China(61627827,61331001,81630046,91539127)the Science and Technology Planning Project of Guangdong Province,China(2015B020233016,2014B020215003,2014A020215031,2017A020215135)+3 种基金the Distinguished Young Teacher Project in Higher Education of Guangdong,China(YQ2015049)the Science and Technology Youth Talent for Special Project of Guangdong,China(2015TQ01X882)Young Teachers Scienti¯c Research Cultivating Fund of South China Normal University(16KJ05)China Postdoctoral Science Foundation(2017M610533).
文摘Microwave-induced thermoacoustic imaging(TAI)is a noninvasive modality based on the differences in microwave absorption of various biological tissues.TAI has been extensively researched in recent years,and several studies have revealed that TAI possesses advantages such as high resolution,high contrast,high imaging depth and fast imaging speed.In this paper,we reviewed the development of the TAI technique,its excitation source,data acquisition system and biomedical applications.It is believed that TAI has great potential applications in biomedical research and clinical study.
文摘We present for the¯rst time in vivo imaging of rat brain using microwave-induced thermoacoustic tomography(TAT).The in vivo imaging of rat brain was realized through an unconventional delivery of microwave energy from the front of rat brain(while the transducer was scanned along coronal plane of the animal brain),which maximized the microwave penetration into the brain.In addition,we found that the imaging contrast was highly dependent on the direction of the electric¯eld polarization(EFP)and that more tissue structures/compositions could be revealed when both X-and Y-EFPs were used for TAT.The in vivo TAT images of rat brain obtained were compared with the 3.0 T MRI images and histological photographs,and numerous important brain anatomical structures were identi¯ed.An example of our TAT approach for imaging a foreign object embedded in a rat brain was also demonstrated.This study suggests that TAT has a great potential to be used in neuroscience studies and in noninvasive imaging of brain disorders.
基金This study was supported by the National Natural Science Foundation of China(Nos.62022037,61775028,81571722,61528401 and 61921002)Guangdong province(2019ZT08Y191)+1 种基金Shenzhen Science and Technology Program(KQTD20190929172743294)Startup grant from Southern University of Science and Technology.
文摘Microwave-induced thermoacoustic imaging(MI-TAI)remains one of the focus of attention among biomedical imaging modalities over the last decade.However,the transmission and dis-tribution of microwave inside bio-tissues are complicated,thus result in severe artifacts.In this study,to reveal the underlying mechanisms of artifacts,we deeply investigate the distribution of specific absorption rate(SAR)inside tissue-mimicking phantoms with varied morphological features using both mathematical simulations and corresponding experiments.Our simulated results,which are confirmed by the associated experimental results,show that the SAR distri-bution highly depends on the geometries of the imaging targets and the polarizing features of the microwave.In addition,we propose the potential mechanisms including Mie-scattering,Fabry-Perot-feature,small curvature effect to interpret the diffraction effect in different scenarios,which may provide basic guidance to predict and distinguish the artifacts for TAI in both fundamental and clinical studies.
基金Project supported by the National Natural Sciences Foundation of China (No. 50536040), the China Postdoctoral Science Foundation(No. 2005038280), and the Natural Sciences Foundation of ZhejiangProvince (No. Y104326), China
文摘A miniature thermoacoustic prime mover, consuming heat to radiate sound, may be considered as a potential way of heat management in microcircuits because of its simplicity and stability. A prototype with variable resonant tube length of 10 to 25 cm was built, and experiments were carried out to observe its performance, such as onset temperature, oscillation amplitude and operating frequency. The results with atmospheric air showed that proper structures and operating conditions can make the system start an oscillation at a temperature lower than 100 ℃, which proves the feasibility of potential usage in electronic units. The influences of stack position, heat input power or tube inclination on the oscillation amplitude, onset temperature and operating frequency are also presented.
文摘Microwave-induced thermoacoustic tomography(TAT)is a rapidly-developing noninvasive imaging technique that integrates the advantages of microwave imaging and ultrasound imaging.While an image reconstruction algorithm is critical for the TAT,current reconstruction methods often creates significant artifacts and are computationally costly.In this work,we propose a deep learning-based end-to-end image reconstruction method to achieve the direct reconstruction from the sinogram data to the initial pressure density image.We design a new network architecture TAT-Net to transfer the sinogram domain to the image domain with high accuracy.For the scenarios where realistic training data are scarce or unavailable,we use the finite element method(FEM)to generate synthetic data where the domain gap between the synthetic and realistic data is resolved through the signal processing method.The TAT-Net trained with synthetic data is evaluated through both simulations and phantom experiments and achieves competitive performance in artifact removal and robustness.Compared with other state-of-the-art reconstruction methods,the TAT-Net method can reduce the root mean square error to 0.0143,and increase the structure similarity and peak signal-to-noise ratio to 0.988 and 38.64,respectively.The results obtained indicate that the TAT-Net has great potential applications in improving image reconstruction quality and fast quantitative reconstruction.
基金supported by the National Natural Science Foundation of China(Nos.12174208 and 32227802)National Key Research and Development Program of China(No.2022YFC3400600)+2 种基金Guangdong Major Project of Basic and Applied Basic Research(No.2020B0301030009)Fundamental Research Funds for the Central Universities(Nos.2122021337 and 2122021405)the 111 Project(No.B23045).
文摘Microwave-induced thermoacoustic imaging(MTI)has the advantages of high resolution,high contrast,non-ionization,and non-invasive.Recently,MTI was used in the¯eld of breast cancer screening.In this paper,based on the¯nite element method(FEM)and COMSOL Multiphysics software,a three-dimensional breast cancer model suitable for exploring the MTI process is proposed to investigate the in°uence of Young's modulus(YM)of breast cancer tissue on MTI.It is found that the process of electromagnetic heating and initial pressure generation of the entire breast tissue is earlier in time than the thermal expansion process.Besides,compared with normal breast tissue,tumor tissue has a greater temperature rise,displacement,and pressure rise.In particular,YM of the tumor is related to the speed of thermal expansion.In particular,the larger the YM of the tumor is,the higher the heating and contraction frequency is,and the greater the maximum pressure is.Di®erent Young's moduli correspond to di®erent thermoacoustic signal spectra.In MTI,this study can be used to judge di®erent degrees of breast cancer based on elastic imaging.In addition,this study is helpful in exploring the possibility of microwave-induced thermoacoustic elastic imaging(MTAE).
基金the National Natural Science Foundation of China under Grant No.12304533Start-up Foundation for Ph.D.of Southwest University of Science and Technology under Grant No.20zx7120.
文摘A microwave-induced thermoacoustic imaging(MITAT)system is a non-destructive physical medical imaging method that combines the advantages of the high contrast of microwave imaging and the high resolution of ultrasound imaging.It uses the microwave as the excitation source and ultrasound as the information carrier.When different kinds of biological tissue absorb electromagnetic energy,it results in localized temperature rises.The thermal expansion will induce ultrasonic signals(i.e.,thermoacoustic signals),known as the thermoacoustic effect.The microwave absorption image of the sample can be reconstructed by algorithm processing.The MITAT contrast depends on different dielectric parameters of different kinds of tissue.We introduce the developed system and its application.In addition,the challenges and prospects of MITAT for further development are discussed.
基金supported by the National Natural Science Foundation of China(No.82071940).
文摘Thermoacoustic imaging(TAI)is an emerging high-resolution and high-contrast imaging technology.In recent years,metal wires have been used in TAI experiments to quantitatively evaluate the spatial resolution of different systems.However,there is still a lack of analysis of the response characteristics and principles of metal wires in TAI.Through theoretical and simulation analyses,this paper proposes that the response of metal(copper)wires during TAI is equivalent to the response of antennas.More critically,the response of the copper wire is equivalent to the response of a half-wave dipole antenna.When its length is close to half the wavelength of the incident electromagnetic wave,it obtains the best response.In simulation,when the microwave excitation frequencies are 1.3 GHz,3.0 GHz,and 5.3 GHz,and the lengths of copper wires are separately set to 11 cm,5 cm,and 2.5 cm,the maximum SAR distribution and energy coupling effciency are obtained.This result is connected with the best response of half-wave dipole antennas with lengths of 11 cm,4.77 cm,and 2.7 cm under the theoretical design,respectively.Regarding the further application,TAI can be used to conduct guided minimally invasive surgery on surgical instrument imaging.Thus,this paper indicated that results can also guide the design of metal surgical instruments utilized in different microwave frequencies.
基金supported in part by the National Key Research and Development Program of China under Grant No.2018YFB1801503National Natural Science Foundation of China under Grants No.61931006,No.82071940,No.62101111,No.U20A20212,No.61921002,and No.U1930127+1 种基金Fundamental Research Funds for the Central Universities under Grants No.ZYGX2020ZB011 and No.ZYGX2019J013Medico-Engineering Cooperation Funds from University of Electronic Science and Technology of China under Grants No.ZYGX2021YGLH205 and No.ZYGX2021YGLH216.
文摘The microwave-induced thermoacoustic imaging(TAI)technology has both the advantages of high contrast of microwave imaging and high resolution of ultrasound imaging(UI),so it has carried out exploratory application research in various areas,such as the early detection of breast tumors and cerebrovascular diseases.However,the microwave generator used in the traditional TAI technology is huge and expensive,and the temporal resolution is also too low due to the single-element scanning mechanism.Thus,it is difficult to meet the needs of clinical applications.In this paper,the iterative process and the analysis of related application scenarios from single-element scanning to portable and array-based TAI,such as the miniaturized microwave generator,handheld antenna,multi-channel data acquisition,and UI/TAIdual-modality imaging,are reviewed,and the future trends of this technology are discussed.This review helps researchers in the field of TAI learn the technological development process and future trends.It also deepens clinicians’understanding of TAI so as to put forward more application requirements.
基金This research was supported by the National Natural Science Foundation of China(62075066)the Science and Technology Planning Project of Guangdong Province,China(2019A1515012054)+2 种基金the Science and Technology Program of Guangzhou(2019050001)the Science and Technology Program of Guangzhou(202201010718)the Key-Area Research and Development Program of Guangdong Province(2019B030335001).
文摘As an emerging hybrid imaging modality,microwave-induced thermoacoustic imaging(MTAI),using microwaves as the excitation source and ultrasonic signals as the information carrier for combining the characteristics of high contrast of electromagnetic imaging and high resolution of ultrasound imaging,has shown broad prospects in biomedical and clinical applications.The imaging contrast depends on the microwave-absorption coe±cient of the endogenous imaged tissue and the injected MTAI contrast agents.With systemically introduced functional nanoparticles,MTAI contrast and sensitivity can be further improved,and enables visualization of biological processes in vivo.In recent years,functional nanoparticles for MTAI have been developed to improve the performance and application range of MTAI in biomedical applications.This paper reviews the recent progress of functional nanoparticles for MTAI and their biomedical applications.The challenges and future directions of microwave thermoacoustic imaging with functional nanoparticles in theeld of translational medicine are discussed.
