Application of Scanning Electron-Acoustic Microscopy to Biological Materials

Gao, Chunming; Zhang, Shuyi; Miao, Pengcheng; Zhang, Zhongning; Li, Ping

doi:10.1023/b:ijot.0000034240.10256.6b

“…The advantages of SEAM are the special imaging abilities for local different thermal or elastic features of surface and subsurface structures with high resolution, by which laminated images of micro-inhomogeneous materials can be obtained nondestructively. 7,10 It is well known that the similar results can also be obtained by conventional acoustic microscopy ͑AM͒. 11 However, due to the thermal wavelength being about one thousand times smaller than the acoustic wavelength and operating in the same frequency and the same material, the operating frequency in SEAM can be decreased three orders of magnitude for obtaining the same special resolution.…”

Section: Introductionmentioning

confidence: 66%

“…Since then, the applications of SEAM for characterizing the microstructures of materials and devices have been widely developed, such as doping regions in semiconductors, 3 magnetic domains in ferromagnetic and microwave materials, 4 ferroelectric domains in ferroelectric ceramics, 5 residual stresses in ceramics 6 and metals, 7 surface and subsurface structures in biological materials, [8][9][10] and so on. The advantages of SEAM are the special imaging abilities for local different thermal or elastic features of surface and subsurface structures with high resolution, by which laminated images of micro-inhomogeneous materials can be obtained nondestructively.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional simulation of electron-acoustic detections

Gao

¹

,

Zhang

²

,

Zhang

³

et al. 2006

The Journal of the Acoustical Society of America

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In electron-acoustic ͑EA͒ detection, a periodically modulated electron beam is impinging on a sample to excite thermo-acoustic signals, and a PZT transducer bonded on the back surface of the sample is used to detect the thermo-acoustic signals. Based on the conditions of the EA detection experiment, theoretical analyses of 3-D temperature distributions in the sample, 3-D elastic fields in the sample and piezoelectric transducer, and piezoelectric output signals of the transducer are given. Generally, the vibration modes and the electrical output signals of the transducer are hard to calculate because of the complicated structures, i.e., complicated boundary conditions, thus a finite element method ͑FEM͒ is used to simulate the electron-acoustic signals. According to the corresponding FEM model, the frequency spectra of the detected EA signals can be calculated. Meanwhile, the related experimental measurements for several homogeneous samples are carried out. Comparing the theoretical simulated results with those of the experiments, it shows that both are in good agreement with each other. Finally, using this FEM model, the dependences of the electron-acoustic signals on the thermal and elastic properties of several samples are investigated.

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“…In the PAPE experiment, the biological tissues are in three conditions: fresh, naturally dry and specially prepared. The specially prepared samples are usually fabricated for Scanning Electron Microscopy (SEM) or Scanning Electron Acoustic Microscopy (SEAM) [11] , which are prepared by four steps: (1) Cleaning the samples with saline solution; (2) fixing the samples with glutaraldehyde solutions; (3) dehydrating the samples gradually with acetone; (4) evaporating the residual water in the samples with a critical-point dryer. Finally the formed samples are with the diameters about 5.6 mm and the thicknesses are about 1.5 mm.…”

Section: Methodsmentioning

confidence: 99%

“…From eqs. (11) and (12), the thermal diffusivity D can be determined by the amplitude and phase of the measured PAPE signals.…”

Section: Theorymentioning

confidence: 99%

See 1 more Smart Citation

Thermal property of biological tissues characterized by piezoelectric photoacoustic technique

Gao¹

2004

Chinese Sci Bull

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A photoacoustic piezoelectric method based on a simplified thermoelastic theory is employed to determine thermal diffusivities of biological tissues. The thermal diffusivities of porcine tissues with different preparation conditions, including fresh, dry and specially prepared conditions, are characterized. Comparing the experimental evaluated diffusivities of the tissues in three conditions with each other, it can be seen that the diffusivities of the fresh tissues are the biggest and the diffusivities of the specially prepared tissues are bigger than that of the dry ones generally. The results show that the piezoelectric photoacoustic method is especially effective for determining macro-effective (average) thermal diffusivities of biological materials with microinhomogeneity and easy to be performed, which can provide useful information for researching thermal characters of biological tissues.Thermal property is one of the most important properties of materials. Several photothermal methods were presented for characterizing the thermal diffusivity of materials, such as mirage effect [1,2] , transient thermal grating [3,4] and pulsed photothermal detection [5] . In these methods, a focused laser beam is used to excite thermal wave, then determine the thermal diffusivity by detecting the thermal wave with different experimental apparatuses and corresponding theoretical calculations. Therefore, these methods are suitable to measure the thermal diffusivity of homogeneous materials or local thermal diffusivity for inhomogeneous materials. On the other hand, a piezoelectric photoacoustic (PEPA) technique has been presented to determine the thermal diffusivity of materials [6] in which the diameter of the optical excitation beam is about the same size of the sample and also of the piezoelectric transducer, and then a simplified thermal-elastic theoretical model is used to determine the macro-effective (average) thermal diffusivity. Recently the PEPA technique has been successfully employed to determine the macro-effective thermal diffusivity of fiber-reinforced composite materials [7] .Generally, the studies of thermal properties of biological tissues and materials are very important for physical therapies and surgical operations, such as radio, laser, infrared, microwave and ultrasound therapies and operations, since the temperature raise and thermal effect of the tissues in the therapies or operations must be considered. Meanwhile, in thermal wave images and detections for biological materials, such as photo-acoustic and electron-acoustic images and detections [8,9] , the depth of the laminated images and detections is dependent on the thermal diffusivity of the materials [10,11] .In this article, the PEPA technique is used to investigate the macro-effective thermal diffusivities of biological tissues in fresh and dry and also after special treatment procedures, in which the porcine tissues of skin, fat, muscle, kidney, liver and heart are studied. The results indicate that the technique provides a very available me...

show abstract

Thermal property of biological tissues characterized by piezoelectric photoacoustic technique

Gao

¹

,

Zhang

²

,

Chen

³

et al. 2004

View full text Add to dashboard Cite

A photoacoustic piezoelectric method based on a simplified thermoelastic theory is employed to determine thermal diffusivities of biological tissues. The thermal diffusivities of porcine tissues with different preparation conditions, including fresh, dry and specially prepared conditions, are characterized. Comparing the experimental evaluated diffusivities of the tissues in three conditions with each other, it can be seen that the diffusivities of the fresh tissues are the biggest and the diffusivities of the specially prepared tissues are bigger than that of the dry ones generally. The results show that the piezoelectric photoacoustic method is especially effective for determining macro-effective (average) thermal diffusivities of biological materials with microinhomogeneity and easy to be performed, which can provide useful information for researching thermal characters of biological tissues.

show abstract

Application of Scanning Electron-Acoustic Microscopy to Biological Materials

Cited by 6 publications

References 5 publications

Three-dimensional simulation of electron-acoustic detections

Three-dimensional simulation of electron-acoustic detections

Thermal property of biological tissues characterized by piezoelectric photoacoustic technique

Thermal property of biological tissues characterized by piezoelectric photoacoustic technique

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