Mami Matsukawa

Doshisha University · Faculty of Science and Engineering

Conventional camera modules use a mechanical system comprising moving parts to change the focal length of the lens by moving it along the optical axis, increasing the volume of the camera. Here, the potential of compact variable-focus lenses was examined to enhance response speed and robustness via a combination of viscoelastic gel films, liquids,...

Conventional camera modules require mechanical moving parts to move their lenses and to adjust their focal points. This paper examines optically tunable lenses with a focal length and lens aperture that can be controlled using ultrasound vibration and a transparent gel. The lens uses the acoustic radiation force, which induces changes in the lens p...

Compound lens systems with mechanical actuators are used to focus objects at near to far distances. The focal length of ultrasound varifocal liquid crystal (LC) lenses can be controlled by modulating the refractive index spatial distribution of the medium through the acoustic radiation force, resulting in thin and fast-response varifocal lenses. Th...

Bone with complex geometry is hard, heterogeneous and anisotropic tissue, which makes ultrasound diagnosis very difficult. Therefore, the simulation of wave propagation is often performed to understand the complicated wave propagation in bone, where we find solid-liquid coexisting conditions. In addition to the diagnosis, one of the recent topics o...

Osteosynthesis materials are used for the fixed treatment of serious bone fractures. Titanium and bioabsorbable poly-L-lactic acid (PLLA) are often used. PLLA is known to have piezoelectricity, and its contribution to bone fracture healing has been discussed. On the other hand, bone fracture healing using low-intensity-pulsed-ultra-sound (LIPUS) is...

Surface plasmon resonance (SPR) ultrasonic sensors are non-resonant and expected to show flat frequency response over a wide frequency range. Then, the sensors seem suitable for the detection of photoacoustic waves. We have developed a simple glass prism SPR sensor with thin Ag layer (deposited by an electron beam evaporator) and checked the freque...

Safe and inexpensive diagnosis of leg bone disease in the field is very important for Thoroughbreds and large animals, because large animals are difficult to transport, and prompt diagnosis is required. The quantitative ultrasound (QUS) is attracting attention for the evaluation of leg bones because it can give us information of elasticity, which i...

Spatiotemporal modulation of refractive index in an optical path medium allows for control of light propagation. This refractive index change (Δn) can be achieved by external stimulation such as temperature or density change, but there is a limit to the extent to which Δn can be controlled by external stimulation acting on a single medium. Here, we...

Low-intensity pulsed ultrasound treatment is known to shorten the healing period of bone fractures by 30%-40%, but the initial mechanism of the healing process remains unknown. One possible mechanism is related to the piezoelectricity of bone. However, the complex geometry of bones results in inherent challenges to evaluating electric fields induce...

Rapid reperfusion therapy can reduce disability and death in patients with large vessel occlusion strokes (LVOS). It is crucial for emergency medical services to identify LVOS and transport patients directly to a comprehensive stroke center. Our ultimate goal is to develop a non-invasive, accurate, portable, inexpensive, and legally employable in v...

For the safe and simple screening of equine leg bones, we applied an ultrasonic Axial Transmission (AT) technique to an equine bone sample with weak bucked shin. Both experimental and simulation studies were performed. For the simulation of Finite Difference Time Domain (FDTD) method, a digital model of the equine leg bone was fabricated. The exper...

This paper proposed a board-mounted ultrasonic variable-focus liquid crystal (LC) lens. The lens controls the focus using the acoustic radiation force generated by the resonant flexural vibration mode. The LC lens was fixed to an aluminum substrate with a hole whose aperture corresponded to the inner diameter of the transducer. The part of the LC l...

In the pharmaceutical field, a technique to level the surface of powdered medicines is important in the dispensing process because the flatness of the powder surface affects the packaging accuracy directly. This paper investigates a method for leveling of the surface profile of powder using ultrasound vibration on a plate. The system used comprises...

The oscillation of shelled microbubbles during exposure to ultrasound is influenced by the mechanical properties of the shell components. The oscillation behavior of bubbles coated with various phospholipids and other amphiphiles has been studied. However, there have been few investigations of how the adsorption conditions of the shell molecules re...

Ultrasound multilayered variable-focus liquid crystal (LC) lenses have better optical performance compared to conventional ultrasound LC lenses. This paper investigates the effect of the distance between two LC layers on the optical characteristics of the lens. The LC molecular orientation in the lens was altered by the acoustic radiation force gen...

No PDF available ABSTRACT Low Intensity Pulsed Ultrasound (LIPUS) can shorten the healing time of fractures by irradiating low-power ultrasound. However, the full mechanism of bone fracture healing is still unknown. One possible mechanism is the ultrasonically induced electrical potential due to the weak piezoelectricity of bone. There are several...

No PDF available ABSTRACT Piezoelectric thin film transducers that can receive and transmit high-frequency and high-intensity ultrasound are powerful tools for future medical and industrial applications. Our group has developed acousto-optic devices where the refractive index can be controlled at high speed and high precision using ultrasound, but...

For simple, safe, portable, and inexpensive evaluation suitable for leg bone diseases of racehorses in the field, an ultrasonic measurement technique was applied to evaluate wave velocities. A digital model of the third metacarpal bone with the bucked shin was fabricated using high-resolution peripheral quantitative computerized tomography data of...

A varifocal concave–convex lens using ultrasound and transparent viscoelastic gel is reported. The configuration of the lens is simple and thin, consisting of four pieces of a piezoelectric ultrasound transducer, a glass disk, and a transparent silicone gel film. It uses a combination of the ultrasound resonant flexural standing- and traveling-wave...

A method to improve the performance of an ultrasound liquid crystal lens is proposed. A double-layer-based lens model tailored based on the liquid crystal’s physical properties, e.g., its dielectric anisotropy and elastic constants, is presented as an alternative method to improve the lens’s optical performance while forming weak anchoring surfaces...

The orientation angles of liquid crystal (LC) molecules were measured during ultrasound vibrations. Light transmitted through a fabricated LC lens was analyzed via the crossed Nicol condition and a crystal rotation method. The LC orientation angle was estimated with a theoretical model, and its distribution in the lens was determined. There was a s...

In this chapter, recent piezoelectric and opto-acoustic studies on bone are introduced. The former are certainly related to ultrasound since piezoelectricity is one of the electro-mechanical properties. The latter are divided into two parts: Photo Acoustics (PA) and Brillouin Scattering (BS). PA is the energy conversion from light to ultrasound whi...

A pump-probe system with a sub-nanosecond pulsed laser is expected to be a compact and inexpensive transient spectroscopic system that enables non-destructive and non-contact evaluations of the physical properties. However, an improvement in the sensitivity and a theoretical model to complement the measurement signal are necessary to obtain the tra...

A simple photoacoustic (PA) method was applied to evaluate bovine cortical bone samples. The target of this study is to evaluate the effects of glycation in bone, which mainly changes properties of collagen due to non-physiological crosslinks. The averaged amplitude of ultrasonic waves generated by the near infra-red pulsed laser irradiation was sm...

The effect of the liquid crystal (LC) layer thickness on the optical characteristics of an ultrasound LC lens was explored. Three LC lenses with differing LC layer thicknesses (100, 200, and 300 µm) were fabricated, and the optical focal lengths were measured by an optical microscope with a varying driving voltage. For the lens with a 200-µm-thick...

New technologies for adaptive optics are becoming increasingly important for miniature devices such as cell-phone cameras. In particular, motion-free autofocusing and optical image stabilization require sophisticated approaches for alternative lens architectures, materials, and processing to replace multiple solid elements. We discuss a new method,...

Although ultrasonically controlled liquid crystal lens may play in important role in future optical systems, many optical properties in the liquid crystal layer are still unclear. Moreover, most of the previously conducted studies control the liquid crystal molecular orientation by an applied electric field using transparent electrodes. In this stu...

The transcranial Doppler method (TCD) enables the measurement of cerebral blood flow velocity and detection of emboli by applying an ultrasound probe to the temporal bone window, or the orbital or greater occipital foramina. TCD is widely used for evaluation of cerebral vasospasm after subarachnoid hemorrhage, early detection of patients with arter...

A variable focus optical lens using a thixotropic gel and ultrasonic vibration is discussed. The surface profile of the gel could be deformed via acoustic radiation force generated by ultrasound. A thixotropic gel in which the viscosity was changed by shear stress was employed as a transparent lens material. The thixotropic gel allowed the lens to...

Diabetic patients have a higher risk of bone fracture than those without diabetes, despite a normal bone mineral density. This higher riskmay result fromthe deterioration of collagen because of glycation. The objective of this study was to investigate the elastic properties of glycated collagen using the micro-Brillouin scattering technique. Using...

A new type of ultrasonically controlled concave liquid crystal lens based on traveling waves (TWs) with a divided electrode structure and an appropriate driving scheme is proposed in this Letter. The lens uses an annular piezoelectric ceramic divided into four parts for four-phase driving and consists of a liquid crystal layer in a sandwich structu...

The success rate of low-intensity pulsed ultrasound (LIPUS) therapy depends on the bone site. However, the initial mechanism of physical stimulation by ultrasound and bone cellular response remains unclear. One possible physical stimulation is the induced electrical potentials due to the piezoelectricity. In this study, the output electrical potent...

The Transcranial Doppler method (TCD) enables the measurement of cerebral blood flow velocity and detection of emboli by applying the ultrasound probe to the temporal bone window, orbital, or greater occipital foramen. TCD is widely used for the evaluation of cerebral vasospasm after subarachnoid hemorrhage, early detection of patients with arteria...

Background The acquisition of a high bone density at a young age is a strategy to prevent fractures/falls later in life. We therefore decided to investigate the increases in cortical thickness (CoTh) and trabecular bone density (TBD) of children. Methods Subjects comprised 1314 students (678 boys and 636 girls) aged between 12 and 18 years. Lifest...

Sand and small stones moving on the riverbed cause topographical changes such as local lowering and scouring. The measurement of particle size distribution of bed load is important to prevent river disasters, and a robust and simple particle sizer without using an electric power supply is required. In this study, a passive piezoelectric sensor for...

An increase in bone fracture risk has been reported in patients with diabetes. To evaluate an early effect of glucose intolerance on bone homeostasis, we have characterized bones from spontaneously diabetic torii (SDT) rats, an animal model of type 2 diabetes in comparison with Sprague Dawley (SD) rats as healthy control. Focusing on early effects...

Titanium implants are widely used clinically. However, surgical failures still occur because of a lack of implant stability. Periprosthetic biomechanical bone properties need to be characterized to better understand osseointegration phenomena and anticipate implant failures. The aim of this study was toinvestigate the spatio-temporal variations of...

To understand the in-plane elastic character of ultrasonic waves in the skull, longitudinal wave velocities were studied in the MHz range using a conventional pulse technique. Taking advantage of the thickness of swine skulls, anisotropic inplane wave velocity changes in the outer and diploe layers were experimentally investigated using structural...

A method to estimate orientation direction of liquid crystal molecules three-dimensionally under ultrasound excitation was proposed and the relationship between the ultrasound vibration and the molecular orientation was discussed. Our group have reported a technique to control orientation direction of liquid crystal molecules using ultrasound vibra...

A finite-difference time-domain (FDTD) technique was used to model the complex propagation of ultrasonic waves through the human radius. A three-dimensional model of the radius, including its uniaxial anisotropy and heterogeneity, was created using structural data obtained from high-resolution peripheral quantitative computed tomographic images. FD...

Piezoelectricity in bone is thought to be a mechanism by which ultrasound promotes the healing of bone fractures. However, few studies have been conducted in the more clinically relevant MHz range. To understand the piezoelectricity in bone, we fabricated ultrasound transducers using bone samples as piezoelectric materials and identified the longit...

The viscosity and the surface profile of a thixotropic gel were controlled via ultrasound vibrations. The ultrasound device consisted of two piezoelectric lead zirconate titanate transducers glued to each end of a 60-mm-long rectangular glass substrate. It generated a 71-kHz flexural standing wave along the length. A 0.9-mm-thick thixotropic gel fi...

Microbubbles shelled with soft materials are expected to find applications as ultrasound-sensitive drug delivery systems, including through sonoporation. Microbubbles with specific vibrational characteristics and long intravascular persistence are required for clinical uses. To achieve this aim, the kinetics of the microbubble shell components at t...

Since the early 1970s it has been pointed out that many higher education students have a fairly large number of mistaken ideas on some Physics topics. Indeed, the term "misconceptions" was introduced for the first time in 1972. This theme is worthy of investigation in order to improve the students' outcomes in basic Physics courses and to tackle th...

Micro-Brillouin scattering was used to measure gigahertz ultrasonic wave velocities in the articular cartilage of a bovine femur. Velocities propagating parallel to the surface of the subchondral bone were 3.36-3.83 × 10³m/s in a dry cartilage sample. Anisotropy measurements were also performed in a 10-μm-diameter local area of the cartilage matrix...

This paper investigates acoustic levitation and noncontact transportation techniques for use with planar objects. An acoustic levitation system was developed that consists of a 1-mm-thick and 400-mm-long bending plate along with two bolt-clamped Langevin-type transducers (BLTs) that have stepped horns. A plane reflector was installed parallel to th...

Photoacoustic microscopy (PAM) has attracted increasing attention for non-invasive functional imaging in biomedicine and biomedical studies. The surface plasmon resonance (SPR) sensor is a potential acoustical detector with high sensitivity and wide bandwidth for use in high-resolution 3D PAM. In this study, we investigated a simple Kretschmann SPR...

This paper investigates acoustic levitation and noncontact transportation techniques for use with planar objects. An acoustic levitation system was developed that consists of a 1-mm-thick and 400-mm-long bending plate along with two bolt-clamped Langevin-type transducers (BLTs) that have stepped horns. A plane reflector was installed parallel to th...

Laser ultrasound technique is suitable to measure the ultrasound velocity of small samples such as meniscus. In this study, longitudinal wave velocities in bovine meniscus samples were measured using a short pulsed laser. The samples were obtained from the knee joint of bovine femurs and five cubes (3×3×3 mm³) were manually manufactured. The ultras...

Low intensity pulsed ultrasound can shorten the healing time of a bone fracture; however, the present technique does not seem not to consider the complicated ultrasound propagation in the body with bone. In this study, the time reversal technique was used to effectively converge ultrasound in the bone part. A three-dimensional distal radius model w...

For the evaluation of small radius of early teens, we have improved the ultrasonic bone measurement system, LD-100 (OYO electric)¹, which can evaluate the distal 5.5 % site of the radius of the non-dominant hand. The system measures two longitudinal waves (fast and slow waves) which propagate in the inside cancellous bone. We can also obtain the sp...

Photoacoustic microscopy (PAM) has attracted attention as a non-invasive observation tool for biomedical studies. However, the spatial resolution is unsuitable for precise imaging of a single cell due to the characteristics of the ultrasonic transducer. In recent years, the surface plasmon resonance (SPR) sensor has been reported as a technique wit...

Nematic liquid crystals are widely used in optical devices such as liquid crystal displays and controlled by electric fields through the liquid crystal layer. The authors have proposed a technique to control the orientation of liquid crystal molecules using ultrasound vibration without indium tin oxide electrodes. An ultrasound liquid crystal cell...

For the ultrasound treatment in brain, such as high intensity focused ultrasound (HIFU), understanding of the complicated ultrasonic propagation in the skull bone is important, because of the anisotropic and heterogeneous character. In this study, we experimentally investigated the ultrasonic wave propagation in the skull sample, considering the an...

Quantitative ultrasound has become a useful technique for bone assessment. Axial transmission technique has demonstrated various advantages over the through-transmission technique. Longitudinal wave and Lamb modes measurements in bone have been extensively reported while shear waves have been neglected. Shear wave velocities are lower than longitud...

It is difficult to perform two-dimensional imaging of elastic properties using Brillouin scattering technique because the weak thermal phonon signal in the sample leads to low measurement accuracy and long measurement times. To improve the phonon signal, we artificially induced acoustic phonons using a ScAlN thin-film piezoelectric transducer, whic...

A pulse wave measurement is effective for the early detection of arteriosclerosis. The pulse wave consists of incident and reflected waves. The reflected wave of the pulse wave measured at the left common carotid artery seems to originate from the vascular beds in the brain. The aim of this study is to know if the reflected waves from the occlusion...

To overcome the problem of low intensity of Brillouin scattered light from thermal phonons, we stimulated the Brillouin scattering by inducing coherent phonons in a glass sample. To develop a completely noncontact measurement method, we induced phonons at 500–800 MHz by a picosecond pulse laser technique and studied how these affect the scattered l...

Hydroxyapatite (HAp) is compatible with bone tissue and used as a bone prosthetic material especially for the implants coating. The c-axis of biological apatite (BAp) in bone is mainly oriented along the bone axis direction due to the mechanical stress produced in this direction. Then, the coating of implant with c-axis parallel oriented HAp thin f...

Since the two-wave separating phenomenon of ultrasound in cancellous bone was found, the detailed behavior of two waves has been investigated in order to put the mechanism into practical use. However, it has been unclear whether the two-waves could be seen in in vivo situation where the cancellous bone is surrounded by cortical bone which has compl...

A variable-focus lens using a combination of liquid crystals and ultrasound is discussed. The lens uses a technique based on ultrasound vibration to control the molecular orientation of the liquid crystal. The lens structure is simple, with no mechanical moving parts and no transparent electrodes, which is helpful for device downsizing; the structu...

While the low-intensity pulsed ultrasound technique has proved useful for healing of bone fractures, the ultrasound healing mechanism is not yet understood. To understand the initial physical effects of the ultrasound irradiation process on bone, we have studied the anisotropic piezoelectric properties of bone in the MHz range. Bone is known to be...

The ITER Remote Experimentation Centre (REC) project (one of the three sub-projects of the International Fusion Energy Research Centre (IFERC)) is progressing under the agreement between the Government of Japan and the European Atomic Energy Community for the joint implementation of the Broader Approach (BA) activities in the field of fusion energy...

Methods for controlling the periodic molecular orientation of liquid crystals using ultrasound vibrations and estimating the orientational direction are proposed. An ultrasonic liquid crystal cell was used, consisting of a liquid crystal layer sandwiched by two glass plates fitted with piezoelectric ultrasound transducers. The transmitted light int...

To predict environmental changes and prevent disasters in rivers it is important to track how the size distributions of sand and stones in the riverbed change over time. In this paper, we used a passive piezoelectric sensor to measure the particle distribution of a simulated bed load. The sensor had a simple, robust structure consisting of a circul...

Ultrasound signals that pass through cancellous bone may be considered to consist of two longitudinal waves, which are called fast and slow waves. Accurate decomposition of these fast and slow waves is considered to be highly beneficial in determination of the characteristics of cancellous bone. In the present study, a fast decomposition method usi...

An ultrasonic bone measurement system, LD-100 (OYO electric),¹ has been developed for the evaluation of the distal 5.5% site of the radius of the non-dominant hand. The system measures two longitudinal waves (fast and slow waves) which propagate in the inside cancellous bone and echo waves reflected from the interface between the cortical and cance...

Nematic liquid crystal is widely used in optical devices such as liquid crystal displays and controlled by electric fields through the liquid crystal layer. Our group has proposed a control technique of liquid crystal molecular orientation using ultrasound vibration without indium tin oxide electrodes [1]. In this study, using ultrasound and nemati...

Ultrasound signal passing through cancellous bone consists of two longitudinal waves: fast and slow waves. Accurate decomposition of the fast and slow waves is supposed to be highly beneficial in order to determine the characteristics of cancellous bone. We applied a fast decomposition method using adaptive beamforming technique with a phase rotati...

Brillouin scattering is a non-contact method to measure wave velocities in the GHz range. One problem of the Brillouin scattering technique is weak light scattering from thermal phonons, which results in the long measurement time and necessity of a complex tandem Fabry-Perot interferometer. To overcome this problem, we have proposed techniques to m...

In vivo elasticity evaluation of meniscus and cartilage is necessary to understand the condition of the joint. Ishihara et al. have used the photoacoustic method with an endoscope.¹ Another possible technique is the laser ultrasound. Making use of the thermoelastic effect, we can stimulate a short longitudinal wave by irradiating the pulsed laser b...

In the original version of the article, the third author name was incorrectly published. The correct name is Kosei Yoh.

Dual X-ray absorptiometry (DXA) is used to diagnose osteoporosis. On the other hand, quantitative ultrasound (QUS) is widely used to assess bone density as part of medical screening as it is relatively inexpensive and easy to perform. Current QUS devices do not share precise ultrasound-related parameters, such as frequency, waveform, beam pattern,...