Wave Penetration Depth Research Articles

Estimation of relative permittivity for measuring soil texture-dependent water content by GNSS-IR

Techniques for measuring the soil moisture content (SMC) using global navigation satellite system-interferometric reflectometry (GNSS-IR) with a positioning antenna have been reported. However, conventional methods are limited to evaluating the relative change in volumetric water content in a dry range for certain soil textures. In this study, we proposed a method to measure relative permittivity using GNSS-IR and evaluated its applicability at two sites with different soil textures and moisture content. The true multipath penetration depth was obtained from the tangent dielectric suitable for the soil textures, and the apparent penetration depth affected by the relative permittivity of the soil was calculated from the signal-to-noise ratio measured by GNSS. The relative permittivity of the soil was obtained from the ratio of these values and compared with the relative permittivity of the SMC sensor. As a result, we could measure soil permittivity according to soil textures from dry to wet conditions from GNSS-IR, except when the true multipath wave penetration depth was less than 1.5 cm, at which only surface reflection occurred. Sandy soils with a low dielectric loss tangent and wet areas with small changes in the depth of penetration of electromagnetic waves are particularly suitable environments for this method.

Near-field Focusing in Ground Penetrating Radar Based on Phase Compensation Algorithm

Underground energy intensity and electromagnetic wave penetration depth are important parameters to characterize the detection performance of Ground Penetrating Radar (GPR). Near-field focusing (NFF) is an effective means to improve the electromagnetic energy fed into the ground by the antennas. In this paper, the phase compensation algorithm considering underground media is derived. In order to verify the effectiveness of the algorithm, the NFF antenna array is proposed. By changing the phase of the NFF array, the focus distance can be adjusted in the range of 400 mm – 800 mm. The maximum field enhancement coefficient in the focal region can achieve 19.2 dB. This shows that NFF array based on phase compensation algorithm has potential application prospects in increasing GPR detection performance.

Spatial variability in melting on Himalayan debris-covered glaciers from 2000 to 2013

Glaciers covered by debris are widespread in the Himalayas. Debris layer makes the melting process of glaciers complicated, and the correlation between the spatial melt differences of glacier and its surface features is still not clear. The aim of this study was to identify possible causes of thickness changes for Himalayan debris-covered glaciers. Firstly, three high resolution Digital Elevation Model (DEM) datasets including SRTM DEM, AW3D and TanDEM-X DEM were used to estimate glacier thickness changes from 2000 to 2013. By checking and removing geometric displacements, systematic deviations and elevation-related bias, as well as correction of radar wave penetration depth in the clean glacier areas, reliable thickness change information in this complex glaciated region were provided. Then debris thicknesses on the glaciers were estimated. The surface lowering caused by ice cliffs or supraglacial ponds significantly reduces debris thickness. Finally, some surface features including debris thicknesses, spatial patterns of supraglacial ponds and ice cliffs extracted from high-resolution satellite images in different times, were comprehensively used to evaluate the main drivers of glacier melting differences. Results demonstrate that spatial variability of glacier melting in Himalayas is caused by the combined effects of debris thicknesses, ice cliffs and supraglacial lakes, with different dominant factors for different regions. The thickened glacier region, which mostly appears above 5300 m a.s.l., with minimal debris cover, displayed large patches of thickening and partial serious thinning in the debris-free areas. Although the thick debris layer (> 0.20 m) would slow down the glacier melting at the low-elevations, it leads to the heavy glacier thinning for the regions located 5000–5300 m a.s.l., where there are dense ice cliffs. In some areas with >1 m of average debris thickness, glaciers have thinned slowly because of erosion from the ice cliffs or large supraglacial ponds. Area and number of cliffs have proven to be key factors in controlling regional ablation for debris-covered glaciers, and supraglacial lakes serve as assistance.

Ultrasonic wave propagation in randomly layered heterogeneous media

This article considers the propagation of high frequency elastic waves in a layered material. Each layer is locally anisotropic and the layer thicknesses and slowness surface orientations are modelled by a (Markovian) process. This work is important in deepening our understanding of the ultrasonic non-destructive testing of carbon fibre reinforced polymer (CFRP) composites and polycrystalline materials. The paper focuses on monochromatic shear waves propagating in two-dimensional ((x1,x3) plane) heterogeneous media. The displacement is in the x2 direction and the model focuses on the reflection and transmission of the wave at layer interfaces. The rotation of the slowness surface in each layer lies in the (x1,x2) plane and varies with the wave propagation direction (x3) only. Expressions for the local and global coefficients for the reflected and transmitted wave amplitudes are derived and shown to satisfy energy conservation. The resulting stochastic differential equations lead to a self-adjoint infinitesimal generator which can be used to produce a Fokker–Planck equation to study the probability distribution of the transmission coefficient. Explicit expressions for the moments of the probability distributions of the power transmission and reflection coefficients are then derived. The dependency of the mean and standard deviation of the power transmission coefficient on the depth of wave penetration, the localisation length, and the direction of wave propagation is then reported.

Surface excitation of focused shear wave beams in soft elastic media: Experiment

Shear waves are employed in medical imaging to reveal variations in the viscoelastic properties of soft tissues, which are useful biomarkers for pathologies such as breast lesions and liver disease. Shear wave excitation methods that employ acoustic radiation force or surface vibration with a small piston have limitations associated with imaging depth and shear wave amplitude. We introduce a new method for surface excitation of shear waves that employs longitudinal motion of a concave-shaped piston source to generate a focused shear wave beam, thereby increasing shear wave amplitude and penetration depth. Focused shear waves are excited in a gel phantom in the frequency range of 200 Hz to 400 Hz using a concave piston with 40 mm radius of curvature and 50 mm diameter. The wave field comprises both transverse and longitudinal displacement components, which are polarized perpendicular and parallel to the propagation direction, respectively. Transversely and longitudinally polarized wave fields are measured using ultrasound speckle tracking. The longitudinally polarized shear wave is of interest because it is measured in elastography applications. Preliminary comparisons exhibit good agreement between measured beam patterns and those predicted by an analytical theory for shear wave beam propagation due to surface excitation with a piston source.

Structural and Elastic Properties of Empty-Pore Metalattices Extracted via Nondestructive Coherent Extreme UV Scatterometry and Electron Tomography.

Semiconductor metalattices consisting of a linked network of three-dimensional nanostructures with periodicities on a length scale <100 nm can enable tailored functional properties due to their complex nanostructuring. For example, by controlling both the porosity and pore size, thermal transport in these phononic metalattices can be tuned, making them promising candidates for efficient thermoelectrics or thermal rectifiers. Thus, the ability to characterize the porosity, and other physical properties, of metalattices is critical but challenging, due to their nanoscale structure and thickness. To date, only metalattices with high porosities, close to the close-packing fraction of hard spheres, have been studied experimentally. Here, we characterize the porosity, thickness, and elastic properties of a low-porosity, empty-pore silicon metalattice film (∼500 nm thickness) with periodic spherical pores (∼tens of nanometers), for the first time. We use laser-driven nanoscale surface acoustic waves probed by extreme ultraviolet scatterometry to nondestructively measure the acoustic dispersion in these thin silicon metalattice layers. By comparing the data to finite element models of the metalattice sample, we can extract Young's modulus and porosity. Moreover, by controlling the acoustic wave penetration depth, we can also determine the metalattice layer thickness and verify the substrate properties. Additionally, we utilize electron tomography images of the metalattice to verify the geometry and validate the porosity extracted from scatterometry. These advanced characterization techniques are critical for informed and iterative fabrication of energy-efficient devices based on nanostructured metamaterials.

Lanthanide-doped NaYF4 near-infrared-II nanothermometers for deep tissue temperature sensing

In this work, different lanthanides (Tm3+, Er3+; Yb3+, Ho3+, Nd3+) were doped into NaYF4 via a high-temperature coprecipitation method, and followed by SiO2 coating to improve the water dispersibility, resulting in NaYF4:Tm3+, Er3+@NaYF4@SiO2 and NaYF4:Yb3+, Ho3+@NaYF4:Nd3+@SiO2 nanoparticles (NPs). The two NPs both exhibited the temperature-dependent second near-infrared (NIR-II) downshifting luminescence over the physiological range. The luminescence ratio of Tm3+ emission at 1460 nm to Er3+ emission at 1525 nm (Tm3+:3H4 → 3F4; Er3+:4I13/2 → 4I13/2) varies with temperature increase, as well as Yb3+ emission at 980 nm and Ho3+ emission at 1150 nm (Yb3+:2F5/2 → 2F7/2; Ho3+:5I6 → 5I8). The highest relative sensitivity of NaYF4:Tm3+, Er3+@NaYF4@SiO2 and NaYF4:Yb3+, Ho3+@NaYF4:Nd3+@SiO2 aqueous suspension is 0.36% K−1 (at 298 K) and 0.76% K−1 (at 343 K), respectively. The biological tests prove the good biocompatibility and low toxicity of the water-soluble NPs. In vitro tissue penetration experiments verify a much better penetration ability of the synthesized NaYF4:Tm3+, Er3+@NaYF4@SiO2 compared with NaYF4:Yb3+, Ho3+@NaYF4:Nd3+@SiO2 NPs. The excellent physiological luminescent thermometry with favor wave penetration depth provides a promising platform in deep tissue temperature measurement, which is very important in vivo biosensing.

Conformal sensor-based harmonic wave technique for in-vivo non-invasive monitoring skin water content

The thermal conductivity of human skin reflects the water content of skin, and thus is a strong indicator of skin health status. The current diagnosis methods for human skin can only detect the water content in a small depth beneath the skin surface, typically within the stratum corneum layer (10–20 μm), which fails to extract the water content in larger depth such as dermis, thereby limiting the timely diagnosis of some severe skin diseases (psoriasis, dry skin, skin eczema, etc.). Here we developed a conformal sensor-based harmonic wave technique which can modulate the thermal wave penetration depth and thus measure the water content in both epidermis and dermis. Variations in water content for three factors (age, site and BMI index) of different subjects were discussed. The progress made so far provides a useful approach for monitoring the water content of human skin and early warning of skin diseases.

Coupled body and surface wave sensitivity kernels for coda-wave interferometry in a three-dimensional scalar scattering medium

SUMMARY Analysis of long recordings of ambient seismic noise has shown to be effective for estimation of seismic responses between points located on the surface. This includes both the ballistic and the coda part of the waveforms. Passive image interferometry is used to analyse perturbations in the reconstructed coda, to detect and locate changes in the medium. This method has been shown to be effective in monitoring variations in seismic velocity produced by a wide range of phenomena. However, localization of the sources of these changes is still an open problem for a 3-D half-space, given the difficulties of integrating body and surface waves within the same framework. In this study, we approach this problem by developing the sensitivity kernels of a scalar model that integrates the body and surface scalar waves. First, we establish a parallel between the penetration depth of the surface waves for the elastic and scalar cases, which equips the latter with a natural scaling with frequency that is otherwise not included in the model. Next, using a variational approach, we quantify how a velocity perturbation in the medium affects the propagation velocity of the surface waves. Based on these results, we extend the sensitivity theory to include the body and surface waves as modes of propagation and detection, as restricted to a 1-D depth-dependent perturbation description, for simplicity. The obtained kernel can be expressed as the sum of a surface and a body waves sensitivity kernels, which are inter-dependent through a set of traveltime distributions. These distributions are estimated with Monte Carlo simulations based on the radiative transfer equations of the system, with the source and the receiver located in the same position at the surface. The sensitivity at depth is in good agreement with previous results based on full wavefield elastic simulations in 3-D inhomogeneous half-space. The temporal evolution of the body and surface waves sensitivity is quantified, as well as the contribution of all the possible modes of propagation and detection to each of these sensitivities. We show how the position of the source affects the sensitivity between the two types of waves. We find that the efficacy of energy conversion from surface to body waves is controlled by the ratio between the surface wave penetration depth and the mean free path, a feature that has not been reported in previous studies. This means that configurations that share this ratio have the same sensitivity as long as all the spatial and temporal variables (e.g. elapsed time, depth) are non-dimensionalized with the mean free path and the mean free time, respectively.

Electromagnetic Heating for Heavy-Oil and Bitumen Recovery: Experimental, Numerical, and Pilot Studies

Summary This study provides an extensive critical review of electromagnetic heating (EMH) methods [inductive heating (IH), low-frequency heating (LFH), and high-frequency heating (HFH)] to highlight their existing challenges in enhanced heavy-oil and oil sands recovery. In general, IH is considered to be less practicable than LFH and HFH. The resistance (ohmic or conduction) heating prevails in LFH while dielectric heating prevails in HFH. Thus, the effectiveness of LFH decreases if reservoir water is overheated to generate steam. Also, the intensity of the energy released and the temperature rise in LFH are not as significant as those in HFH. LFH also fails in penetrating the media with breaks, heterogeneities, and in partially saturated media (e.g., when some oil saturation has been produced). These challenges might somewhat be remedied by HFH at the expense of reducing the electromagnetic (EM) wave penetration depth. The advantages of HFH include remote heating through a desiccated reservoir region around the EM energy source, higher intensity of the energy released and greater temperature rise, and better EM wave penetration through partially saturated media with breaks and heterogeneities. The caveat, however, is that the practical application of HFH could be more expensive than LFH. Besides, the lower depth of EM wave penetration in HFH remains a challenge. During HFH, the temperature increase occurs as a result of the induced molecular rotation in the dielectric material, in particular if the material contains more polar compounds. The polar molecules follow the EM field. This increases the internal molecular friction within the material and generates heat, leading to the rise of temperature. Because the heat generated is a function of the stored (absorbed) energy in the reservoir, the dielectric constant or the real permittivity of the reservoir should be enhanced to enhance the performance of HFH. This ensures that the temperature has risen reasonably in a reasonable amount of time with a reasonable amount of electricity consumption. However, to generate a uniform rise in temperature on a large scale away from the wellbore, the imaginary permittivity of the material should be reasonably lowered, too, for maximizing the penetration of the EM wave (while the real permittivity is an indication of the degree of polarization, the imaginary permittivity is associated with dielectric losses). Lowering the imaginary permittivity away from the wellbore helps minimize the effects of steam condensation (condensate formation retards the EM wave propagation) or delay steam condensation because the reservoir temperature is reduced during the later stages of oil production. The thermal conductivity of the formation should also be enhanced, especially away from the wellbore to generate a more uniform rise in temperature. These three reservoir improvements (enhancing real permittivity, lowering imaginary permittivity, and enhancing thermal conductivity) in an attempt to enhance EMH underpin the rationale behind proposing future optimizations of EMH, and in particular, HFH.

Rayleigh wave propagation at the boundary surface of dry sandy ($SiO_2$) thermoelastic solids

PurposeThe purpose of study to this article is to analyze the Rayleigh wave propagation in an isotropic dry sandy thermoelastic half-space. Various wave characteristics, i.e wave velocity, penetration depth and temperature have been derived and represented graphically. The generalized secular equation and classical dispersion equation of Rayleigh wave is obtained in a compact form.Design/methodology/approachThe present article deals with the propagation of Rayleigh surface wave in a homogeneous, dry sandy thermoelastic half-space. The dispersion equation for the proposed model is derived in closed form and computed analytically. The velocity of Rayleigh surface wave is discussed through graphs. Phase velocity and penetration depth of generated quasi P, quasi SH wave, and thermal mode wave is computed mathematically and analyzed graphically. To illustrate the analytical developments, some particular cases are deliberated, which agrees with the classical equation of Rayleigh waves.FindingsThe dispersion equation of Rayleigh waves in the presence of thermal conductivity for a dry sandy thermoelastic medium has been derived. The dry sandiness parameter plays an effective role in thermoelastic media, especially with respect to the reference temperature for η = 0.6,0.8,1. The significant difference in η changes a lot in thermal parameters that are obvious from graphs. The penetration depth and phase velocity for generated quasi-wave is deduced due to the propagation of Rayleigh wave. The generalized secular equation and classical dispersion equation of Rayleigh wave is obtained in a compact form.Originality/valueRayleigh surface wave propagation in dry sandy thermoelastic medium has not been attempted so far. In the present investigation, the propagation of Rayleigh waves in dry sandy thermoelastic half-space has been considered. This study will find its applications in the design of surface acoustic wave devices, earthquake engineering structural mechanics and damages in the characterization of materials.

Planetary radar science case for EISCAT 3D

Abstract. Ground-based inverse synthetic aperture radar is a tool that can provide insights into the early history and formative processes of planetary bodies in the inner solar system. This information is gathered by measuring the scattering matrix of the target body, providing composite information about the physical structure and chemical makeup of its surface and subsurface down to the penetration depth of the radio wave. This work describes the technical capabilities of the upcoming 233 MHz European Incoherent Scatter Scientific Association (EISCAT) 3D radar facility for measuring planetary surfaces. Estimates of the achievable signal-to-noise ratios for terrestrial target bodies are provided. While Venus and Mars can possibly be detected, only the Moon is found to have sufficient signal-to-noise ratio to allow high-resolution mapping to be performed. The performance of the EISCAT 3D antenna layout is evaluated for interferometric range–Doppler disambiguation, and it is found to be well suited for this task, providing up to 20 dB of separation between Doppler northern and southern hemispheres in our case study. The low frequency used by EISCAT 3D is more affected by the ionosphere than higher-frequency radars. The magnitude of the Doppler broadening due to ionospheric propagation effects associated with traveling ionospheric disturbances has been estimated. The effect is found to be significant but not severe enough to prevent high-resolution imaging. A survey of lunar observing opportunities between 2022 and 2040 is evaluated by investigating the path of the sub-radar point when the Moon is above the local radar horizon. During this time, a good variety of look directions and Doppler equator directions are found, with observations opportunities available for approximately 10 d every lunar month. EISCAT 3D will be able to provide new, high-quality polarimetric scattering maps of the nearside of the Moon with the previously unused wavelength of 1.3 m, which provides a good compromise between radio wave penetration depth and Doppler resolution.

Effect of the Geometries of Ge-Sb-Se Chalcogenide Glass Tapered Fiber on the Sensitivity of Evanescent Wave Sensors

A geometrical optimization study of Ge-Sb-Se chalcogenide glass tapered fiber sensors for concentration sensing of methanol is presented. The effects of the geometrical parameters such as taper waist diameter and transition region lengths on the evanescent wave penetration depth are discussed based on the ray-tracing theory. Numerical analysis results demonstrate that the performance of the tapered fiber sensor can be enhanced by decreasing the transition length of the down-taper combined with increasing the transition length of the up-taper. A homemade tapering platform enables controlling the taper waist diameter and transition region length of the tapered fiber accurately. An experimental study using tapered fiber sensors with different transition region lengths is carried out to detect the concentration of methanol aqueous solution. The highest sensitivity of 0.0120 a.u./% is obtained from the tapered fiber with a down-taper transition length of 5.4 mm and an up-taper transition length of 7.9 mm, which agrees with the trend presented by the simulation results. The effects of symmetric and asymmetric tapered fiber structure on the sensing characteristics are also investigated.

Mode Analysis of Pt/LGS Surface Acoustic Wave Devices.

Platinum (Pt) gratings on langasite (LGS) substrates are a widely used structures in high temperature surface acoustic wave (SAW) devices. Multiple modes can be excited in PtLGS SAW devices owing to the heavy weight of the Pt electrode and leaky waves in the LGS substrate. In this work, we report on a detailed mode analysis of PtLGS SAW devices, where three commonly used LGS cuts are considered. A three-dimensional (3D) finite element method (FEM) numerical model was developed, and the simulation and experiment results were compared. The experiment and simulation results showed that there are two modes excited in the PtLGS SAW devices with Euler angle (0, 138.5, 27) and (0, 138.5, 117), which are Rayleigh-type SAW and SH-type leaky wave, respectively. Only the Rayleigh-type mode was observed in the PtLGS SAW devices with Euler angle (0, 138.5, 72). It was found that the acoustic velocities are dependent on the wavelength, which is attributed to the change of wave penetration depth in interdigital transducers (IDTs) and the velocity dispersion can be modulated by the thickness of the Pt electrode. We also demonstrated that addition of an Al2O3 passivation layer has no effect on the wave modes, but can increase the resonant frequencies. This paper provides a better understanding of the acoustic modes of PtLGS SAW devices, as well as useful guidance for device design. It is believed that the Rayleigh-type SAW and SH-type leaky waves are potentially useful for dual-mode sensing applications in harsh environments, to achieve multi-parameter monitoring or temperature-compensation on a single chip.

Characterisation of Biological Materials at THz Frequencies by Attenuated Total Reflection: Lard

The penetration depth of an evanescent wave in Attenuated Total Reflection (ATR) is dependent on the wavelength of the radiation utilised. At THz frequencies, the penetration depth into biological tissues is in the order of 0.1 to 0.5 mm; rendered pig lard was used as a model sample in this study. A method for the direct measurement of the evanescent wave penetration depth is presented which allows for the estimation of the dispersion of the complex refractive index by using the reflection of the evanescent wave from varying sample depths. The method employs frustrated total internal reflection, and has been demonstrated by using the THz/Far-IR beamline at the Australian synchrotron, and modelled using finite difference time domain (FDTD) simulations.

Hydrodynamics of Quartz-Crystal-Microbalance DNA Sensors Based on Liposome Amplifiers

The quartz crystal microbalance (QCM) is widely used to study surface adsorbed molecules, often of biological significance. However, the relation between raw acoustic response (frequency shift $\Delta f$ and dissipation factor $\Delta D$) and mechanical properties of the macromolecules still needs to be deciphered, particularly in the case of suspended discrete particles. We study the QCM response of suspended liposomes tethered to the resonator wall by double stranded DNA, with the other end attached to surface-adsorbed neutravidin through a biotin linker. Liposome radius and dsDNA contour length are comparable to the wave penetration depth ($\delta\sim 100\ \mathrm{nm}$). Simulations, based on the immersed boundary method and an elastic network model for the liposome-DNA complex, are in good agreement with experimental results for POPC liposomes. We find that the added stress at the resonator surface, i.e. the impedance Z sensed by QCM, is dominated by the flow-induced liposome surface-stress, which propagates towards the resonator by viscous forces. QCM signals are extremely sensitive to the liposome's height distribution P(y) which depends on the actual number and mechanical properties of the tethers, in addition to the usual local attractive/repulsive chemical forces. Our approach helps in deciphering the role of hydrodynamics in acoustic sensing and revealing the role of parameters hitherto largely unexplored. A practical consequence would be the design of improved biosensors and detection schemes.

Propagation of Rayleigh waves on curved surfaces

The propagation and properties of Rayleigh waves on curved surfaces are investigated theoretically. The Rayleigh wave dispersion equation for propagation on a curved surface is derived as a parabolic equation, and its penetration depth is analyzed using the curved surface boundary. Reciprocity is introduced to model the diffracted Rayleigh wave beams. Simulations of Rayleigh waves on some canonical curved surfaces are carried out, and the results are used to quantify the influence of curvature. It is found that the velocity of the surface wave increases with greater concave surface curvature, and a Rayleigh wave no longer exists once the surface wave velocity exceeds the bulk shear wave velocity. Moreover, the predicted wave penetration depth indicates that the energy in the Rayleigh wave is transferred to other modes and cannot propagate on convex surfaces with large curvature. A strong directional dependence is observed for the propagation of Rayleigh waves in different directions on surfaces with complex curvatures. Thus, it is important to include dispersion effects when considering Rayleigh wave propagation on curved surfaces.

An In-silico Simulation of Pressure Wave Excursions after Impact to the Frontal Lobe of a Homogenous Model of the Brain

Traumatic impacts to the crania are known to have chronic effects on cerebral tissue and cognitive function. However, the inaccessibility of healthy brain tissue has limited studies of the mechanical behavior of the brain during impact. Consequently, it is uncertain how specific impacts lead to injury. The well-known Head Injury Criterion (HIC) metric is stochastic in nature. Therefore, it cannot provide deterministic indications of the severity of certain impacts and is ambivalent to trauma location.This research investigated an impact to the anterior region of an isomorphic model of intracranial tissue. The impact was 18 mm lateral of the sagittal plane. The impact propagation through the brain model was observed with a focus on the depth of wave penetration. The brain model was simplified by removing material property variations across white and grey matter and in the ventricles that contain cerebrospinal fluid regions. Ultimately, homogeneity of the simplified model was assumed to show more conservative results than what may be observed in practice.The simulation showed the significance of the initial impact magnitude and location with respect to any propagated wave. It was observed that despite minimizing the effect of damping in the model, pressure waves were not significant at the anterior of the brain. Thus, it was concluded that it is unlikely that secondary impact during TBI has a significant correlation to the location and severity of injury sustained.

Optimization of Bending Angle of Fiber Optic Sensor for Non-Invasive Blood Glucose Measurement

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Stethoscope-type 3ω independent detector for fast measurement of material thermal conductivity.

As one of the most basic properties of materials, thermal conductivity is a key parameter to investigate the analysis and design of the particular thermal process, such as the analysis of the thermal/cool energy storage and release process, the thermal/cool energy storage system design, and so on. Also, it is the foundation of energy technology development. In order to overcome the problem that the measurement frequency of a polyimide substrate independent detector is lower and the measurement time is longer, based on the relationship among 3ω detection frequency, thermal wave penetration depth, and thermal properties of the substrate material, this paper developed a stethoscope-type 3ω independent detector based on a sapphire substrate for fast measurement of material thermal conductivity. Nickel, with a high resistance temperature coefficient, was used as the metal detector. The influence of the width of the nickel metal detector and the thickness of the sapphire substrate on the measurement accuracy was analyzed by introducing an effective heat flow ratio. The sapphire substrate independent detector was calibrated by using copper, aluminum, 304 stainless steel, quartz glass, ethylene glycol, and plexiglass with known thermal conductivities. The experiment shows that the measurement frequency of the stethoscope detector can be ten times higher than that of a Kapton film independent detector. Its measurement time is only one tenth of that of the Kapton film independent detector.