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In this paper, micro-capsule destruction by pulse waves for drug delivery systems (DDS) is discussed. In a DDS using ultrasound, micro-capsules with an elastic thin shell release the enclosed drugs at the moment of their destruction. An optical observation of the micro-capsule destruction by the pulse wave, using a highspeed video camera, is carried out. As the pulse duration is increased, the violent capsule destructions appear. Under the driving conditions of the pulse wave, the internal gas of the microcapsule cannot be emitted completely towards the surrounding media and a part of the internal gas remains inside the broken shell. For the complete emission of the internal gas, a sufficient pulse duration is necessary after the capsule destruction. It is found that the capsule destruction by the pulse wave mostly depend on the amplitude of the driving sound pressure rather than the pulse duration.

Micro‐capsule trapping and destruction in an acoustic standing wave is examined. In an ultrasonic drug delivery system, micro‐capsules are expected to release the drugs inside at the moment of their destruction. In this report, optical observation of capsule destruction using a high‐speed video camera is carried out. As the driving sound pressure of the standing wave is increased, the capsule can be trapped at the anti‐node. The sound pressure threshold for capsule trapping depends on the radii of micro‐capsules and is lowest under the resonance condition, i.e., the larger capsule can be trapped easily at the anti‐node; however, the larger‐than‐resonance capsule cannot be trapped at the anti‐node. Micro‐capsule destruction is also examined in continuous and the pulsed waves. At the moment of destruction, the micro‐capsule has a non‐spherical shape and the internal gas jets out of the capsule instantly. As the driving pulse duration is increased, the capsule destruction becomes violent. The sound pressure threshold for capsule destruction has its lowest value at resonance. Capsule destruction by pulsed waves depends mostly on the amplitude of the sound pressure rather than the pulse duration.

A high-speed variable-focus liquid optical lens using acoustic radiation force is proposed. The lens consists of a piezoelectric ring and a lens cell filled with degassed water and silicone oil. The profile of the oil-water interface can be rapidly varied by applying acoustic radiation force from the ultrasonic transducer, allowing the liquid lens to be operated as a variable-focus lens. The fastest response time of 6.7 ms was obtained with silicone oil with a kinematic viscosity of 100 cSt. The lens could scan at focal lengths of from 7.0 to 14.5 mm at 1 kHz in the axial direction.

In ultrasonic pumps, liquid is sucked into a pipe whose end is faced at an ultrasonic vibrating surface with a small gap. To simulate the pump operation, a model of the ultrasonic pump based on the squeeze film theory is presented in this paper. Nonlinear compressibility is introduced to the liquid in the gap, and the static pressure is calculated as a time average over the period of the ultrasonic vibration of the gap. We investigate the applicability of the model by comparing the simulated static pressure with the experimental pump pressure. The simulated static pressures as a function of the gap and the vibration displacement amplitude approximately agree with the experimental pump pressures if the squeeze film factor is suitably chosen.

"null", If a pipe end is faced at an ultrasonic vibrating surface with a small gap in the liquid, the liquid is sucked into the pipe. The ultrasonic pump under our investigation is based on this phenomenon. In the first part of this paper, we explore the relationships between the number of pipes and the pump characteristics. The flow rate is improved proportionally to the number of pipes if a piston-vibrating surface is used, whereas the maximum flow rate is improved by a factor of only 1.5 using two pipes if a bending vibrator is employed. Second, we research how the inner diameter of the pipe affects the flow rate. The maximum flow rate is improved by a factor of 1.9 if the inner diameter is changed from 3.5 to 5.0 mm.

Introduction Delayed engraftment and subsequent engraftment failure cause fatal complications including severe infection and lead to poor prognosis after allogeneic hematopoietic stem cell transplantation (allo-SCT). We have previously reported that hemophagocytic syndrome (HPS) induced by uncontrolled macrophage activation in bone marrow had high mortality due to engraftment failure (BMT.2012;47:387–394). Macrophages are phagocytic cells with abilities of phagocytosis, antigen-presenting, and secretion of cytokines. Although phagocytosis reflects only a part of their activation, their morphological changes or increased cell counts can be used for evaluating their activation. Our hypothesis was that macrophage activation would have intrinsic value whether it would meet diagnostic criteria for HPS or not. In this study, we analyzed the clinical impact of activated macrophages in bone marrow during the peri-enrgaftment period in patients with delayed engraftment and engraftment failure. Patients and Methods We retrospectively reviewed 212 adult patients who received a first allo-SCT for hematological diseases from January 2006 to December 2011 in our institution. Delayed engraftment was defined that neutrophil engraftment was achieved later than day 15, 20 and 27 post peripheral blood stem cell, bone marrow and cord blood transplantation, respectively, whereas engraftment failure was defined that engraftment was never observed including those who received second allo-SCT. Bone marrow clot sections of day 14±7 and day 28±7 post allo-SCT were analyzed by staining macrophages with anti-CD163 monoclonal antibody. CD163 is a member of the scavenger receptor cystein-rich superfamily and is an exclusive marker for macrophages, playing a major role in the scavenging components of damaged cells. Recently macrophages with an unrestrained proinflammatory activation state along with highly expressed CD163 were reported (JCI.2011;121:985–97). Therefore, the total number of CD163 positive-macrophages was counted in three fields at a 200-fold magnification. We calculated the ratio of macrophages (mac ratio), dividing the number of macrophages by the total cell counts per field. Total area of CD163 positive-macrophages was measured with a digital microscope (BZ-9000, Keyence, Japan). The size of a macrophage was estimated total area of CD163+/ number of CD163 positive-macrophages. Results Delayed engraftment and engraftment failure were observed in 17 (8.0%) and 7 (3.3%) out of 212 patients, respectively. Median mac ratio of day 14 marrow was 0.09 (0.03-0.28), 0.54 (0.15-0.82) and 0.57 (0.46-0.65), whereas that of day 28 marrow was 0.05 (0.02-0.08), 0.25 (0.14-0.70) and 0.53 (0.33-0.82) in normal engraftment, delayed engraftment and engraftment failure groups, respectively. Both delayed engraftment and engraftment failure groups had significantly higher mac ratio in both day 14 and 28 than normal engraftment group (p=0.0002, 0.002 at day 14, p=0.0000, 0.0004 at day 28, respectively). Between delayed engraftment and engraftment failure groups, mac ratio was significantly higher in engraftment failure group in day 28 marrow (p=0.04), while no difference was observed in day 14 marrow (p=0.64). Higher mac ratio than 0.5 could predict delayed engraftment or engraftment failure in day14 marrow (p=0.002), and engraftment failure in day 28 marrow (p=0.000). Only 1 patient of 7 engraftment failure patients (14%) met the criteria of HPS, while mac ratio of 5 patients (71%) was >0.5 at day14. The size of macrophages at day 14 was significantly larger in delayed engraftment and engraftment failure groups than normal engraftment group (p=0.03; 1682.2 μm2 in engraftment failure, 1537.1 μm2 in delayed engraftment and 1054.3 μm2 in normal engraftment, respectively), which indicated the activation of macrophages. Conclusion Increased number of activated macrophages in bone marrow during the peri-engraftment period post allo-SCT was associated with subsequent delayed engraftment and engraftment failure. Our data also suggest that delayed engraftment and engraftment failure could be predicted by the mac ratio of day 14 and 28 marrow, which could be more sensitive marker than the criteria of HPS. This study suggests rationale for macrophage-targeted therapy among patients with the proliferation of activated macrophages in their bone marrow to prevent engraftment failure. Disclosures: No relevant conflicts of interest to declare.

Arterial filters are employed in extracorporeal circulations to remove microbubbles and thrombus from the blood flow and prevent the emboli. Filters with mesh structure have a risk to generate the thrombi when the blood flows through it. In this report, a meshless filter using ultrasound is discussed. The filter consists of an aluminum cylinder (length: 130 mm; inner diameter: 30 mm) and two annular ultrasound PZT transducers. The filter has one inlet at the center of the side and two outlets at both ends. By exciting the transducer, the acoustic traveling wave can be generated in the liquid inside the filter. Air bubbles flowing from the inlet can be led toward the outlet by acoustic radiation force. The characteristics of the filter were investigated through a circulation system using distilled water at the driving frequencies of 200 kHz and 1 MHz. Flow and injected air were set as 5.0 l/min and 10 ml/min, respectively. The microbubbles were filtered by using ultrasound and the amount of filtered bubbles was increased with theinput voltage to the transducer: 50.6 and 53.7% of microbubbles were filtered at 200 kHz and 1 MHz, respectively, when the input voltage was 100 Vpp.

Acoustic radiation force impulse (ARFI) has been actively studied in the field of medical ultrasonics. ARFI generates shear wave in the tissue to evaluate the tissue hardness using that velocity, and this method is applied to the diagnosis of liver tumor. Generally, long pulses are used for ARFI; therefore, we need to take account of thermal and physical effects on biological body. According to the regulation of Food and Drug Administration (FDA), the acoustic output of diagnostic ultrasound is approved as follows: Ispta.3

Varifocal imaging using an optical lens that employs acoustic radiation force and a viscoelastic material and that has no mechanical moving parts is investigated. The lens has a simple and thin structure that consists of an annular ultrasonic transducer and silicone gel. An axially symmetric acoustic standing wave can be generated in the gel by exciting a vibration mode in the radial direction on the transducer. The lens profile can be altered by varying the acoustic radiation force of the transducer. The focal length can be controlled by varying the transducer input voltage so that the lens functions as a variable-focus lens.

Hollow microcapsules have been considered for potential application as drug or gene carriers. Targeted drug or gene release to tumor vascular can be achieved by destroying the capsules by high-intensity ultrasound. This report investigates fabrication of microcapsules having biocompatible polylactic acid (PLA) shell and the mechanical property for the destruction under ultrasound irradiation. The PLA hollow microcapsules with the diameter of 1 to 35 μm were fabricated by double emulsion method. Red fluorescent dye which is substitute for drug was enclosed into the capsules. The capsules have trilaminar structure. Inner air is surrounded by red fluorescent, and the PLA shell encloses them. Shell thickness of capsules was distributed from 100 nm to 3 μm. Destruction of the fabricated capsules was investigated by using ultrasound pulse with the center frequencies from 500 kHz to 2 MHz. The behavior of capsule was observed by using an optical microscope under ultrasound irradiation. The frequency dependence of the capsule destruction was investigated and 35% of the capsules with the resonance size was destroyed with 400 kPa at 700 kHz. The capsule shell was ruptured by the ultrasound, and then the inner dye was released; the dye was completely released for 120 seconds under ultrasound irradiation.

We have succeeded in the noncontact transportation of ethanol droplets inside a semi cylindrical acoustic waveguide. The waveguide was composed of a vibration bottom plate and a semi cylindrical reflector, and a propagating acoustic field was excited in the waveguide. The droplet was levitated at the nodal position of the standing wave mode in the cross section of the waveguide and transported by the traveling wave component in the horizontal direction. The transportation distance was 65 mm and the terminal velocity reached 2.3 m/s when the droplet was 1.5 mm in diameter and 1.38 g in weight.

Abstract 4550 Background: Occasional cases of post-transplant liver dysfunction which resemble autoimmune hepatitis have been reported. Although pathologically indistinguishable from ‘definite’ autoimmune hepatitis, they occur with an alloimmune etiology because the liver is of recipient origin while the immune system is of donor origin (therefore, it is autoimmune “like” hepatitis (AILH) precisely). However, the incidence and clinical features of autoimmune-like hepatitis following allogeneic stem cell transplantation (allo-HSCT) are hitherto unknown. Therefore, the aim of this study was to investigate the characteristics of AILH after allo-HSCT mainly in comparison with hepatic GVHD. Methods: A total of 66 patients (median age=38) with malignant (n=62) and benign (n=4) hematological disorders were enrolled in this study, who underwent liver biopsy because of liver complication after allo-HSCT at the Japanese Red Cross Nagoya First Hospital between 1991 and 2010. Fifteen of the 66 patients were autopsied. Because two patients received liver biopsy twice separately, 68 specimens were investigated. The clinical course, liver function tests (T-Bil, AST, ALT, ALP, γGTP, LDH), and response to the treatment were investigated in each case. Clinical characteristics of each pathological diagnosis, especially AILH and GVHD, were studied. AILH was pathologically diagnosed according to the revised International Autoimmune Hepatitis Group diagnostic criteria (interface hepatitis, predominantly lymphoplasmacytic infiltrates and resetting of liver cells), while hepatic GVHD was based on dysmorphic or destroyed small bile dusts with infiltration of CD8+ T cells forming lymphoepithelial lesions. The onset of the hepatic complications was defined as the day when three of the liver function tests changed abnormal. Results: Conditioning regimes were myeloablative (n=52), and reduced intensity (n=14). Donors were HLA-matched (n=51) and mismatched (n=15), related (n=39) and unrelated (n=27). Graft sources were bone marrow (n=54), peripheral blood (n=11), and cord blood (n=1). GVHD prophylaxis consisted of a combination of short-term methotrexase and tacrolimus (n=23) or cyclosporine (n=43). Pathological diagnosis of hepatic complications included AILH (n=5), GVHD (n=23), ischemic colangiopathy (n=11), VOD/SOS (n=6), steatohepatitis (n=4), and others (n=17). Comparing AILH with GVHD, the onset of AILH (median 320, range 133–2631) was significantly later than that of GVHD (median 90, range 29–422) (p=0.005). Consequently, the day of biopsy was also delayed significantly (AIH: median 349, range 187–2647; GVHD: median 133, range 34–586) (p=0.01) in the patients of AILH. Elevation of AST (AILH: median 628, range 508–1215; GVHD: median 289, range 107–1358) was significantly higher in patients with AILH than patients with GVHD (p=0.007). T-Bil (AILH: median 9.8, range 1.2–34.9; GVHD: median 3.3, range 1.2–31.6) and ALT (AILH: median 628, range 517–1586; GVHD: median 573, range 216–2065) were relatively higher in patients with AILH. Immunologically, two of four patients tested were positive for anti-smooth muscle antibody, and one patient out of four tested had a high anti-nuclear antibody titer (1:360) in AILH group. Three of five patients (60%) with AILH and eighteen of 23 patients (78%) with GVHD received steroid therapy and other patients received only supportive care. In patients received steroid therapy, all three patients (100%) improved in AILH group, while only 12 of 18 patients (66%) improved in GVHD group. In addition, all liver function tests were normalized in three patients with AILH (60%), while in only five patients with GVHD (22%). After a median follow-up of 7.4 years, the estimated 5-year OS was 31.4% in this whole cohort. The estimated 5-year OS was 75.0% in patients with AILH and 29.8% in patients with GVHD, respectively. Conclusion: AILH was not a rare hepatic complication following allo-HSCT because five cases (8.5%) in this study were diagnosed with AILH. Compared with GVHD, AILH showed later onset, and higher elevations of transaminases. Treatment with steroids dramatically improved hepatic dysfunction in AILH. Therefore, AILH is a disease entity different from hepatic GVHD, and it should be included in the differential diagnosis of hepatic complication after allo-HSCT. Disclosures: No relevant conflicts of interest to declare.

The high-speed scanning of a focal point by a variable-focus liquid lens is discussed. We have investigated a high-speed variable-focus liquid lens using acoustic radiation force. It consists of a cylindrical aluminum cell with a diameter of 6 mm and a thickness of 3 mm filled with water, silicone oil, and an ultrasound transducer. The oil-water interface can be deformed and the focal point can be changed by controlling input voltage. By exciting with an amplitude modulation (AM) signal, the vibration on the oil-water interface synchronized with the modulation wave was generated. The vibration displacement amplitude decreased with an inverse proportion of f0.66 over 100 Hz, which is close to the resonance frequency of the lens. The path of the laser beam transmitted through the lens was calculated by ray-tracing simulations. The lens could scan at focal lengths of from 7.0 to 14.5 mm at 1 kHz in the axial direction.

We constructed the experimental system with a laser Doppler vibrometer (LDV) for measuring the vibration of a single microbubble. It was demonstrated that the system enabled the capture of the vibration with an amplitude of nanometer order. We attempted to experimentally measure the resonant characteristics of a bubble attached to a wall by using the system. As a result, we succeeded in measuring the characteristics and evaluating the Q factor and the resonant radius at a driving frequency of 27.8 kHz, although these values are different from those predicted on the basis of the theory for a single free bubble. The LDV measurement system is expected to an effective tool for evaluating bubble vibrations with very small displacement amplitudes, such as the vibration of a microcapsule.

The high-speed scanning of a focal point by a variable-focus liquid lens is discussed. We have investigated a high-speed variable-focus liquid lens using acoustic radiation force. It consists of a cylindrical aluminum cell with a diameter of 6 mm and a thickness of 3 mm filled with water, silicone oil, and an ultrasound transducer. The oil–water interface can be deformed and the focal point can be changed by controlling input voltage. By exciting with an amplitude modulation (AM) signal, the vibration on the oil–water interface synchronized with the modulation wave was generated. The vibration displacement amplitude decreased with an inverse proportion of f 0.66 over 100 Hz, which is close to the resonance frequency of the lens. The path of the laser beam transmitted through the lens was calculated by ray-tracing simulations. The lens could scan at focal lengths of from 7.0 to 14.5 mm at 1 kHz in the axial direction.

Abstract 3455 Background: Iron overload (IO) is a relatively common complication in allogeneic hematopoietic stem cell transplant (AHSCT) recipients who frequently need red blood cell transfusions. The estimation of IO is currently based on serum ferritin (SF) level, but in HSCT recipients, many confounding factors can result in ferritin overestimation. Non-transferrin-bound iron (NTBI), which is detected in conditions of iron overload when transferrin becomes fully saturated and unable to bind excess iron, is thought to catalyze the formation of reactive radicals. We studied the prevalence of IO in adult AHSCT survivors and quantified IO by determining NTBI. Methods: A total of 116 patients were enrolled in this study, who underwent their first AHSCT in our institute, survived ≥100 days from AHSCT in continuous remission and were returning for follow-up at our institute between August 2009 and March 2010. Results: The median age at AHSCT was 37 (range, 17–65) years. Primary diagnosis included acute leukemia/myelodysplastic syndrome (n=77) and aplastic anemia (n=14). Conditioning regimens were myeloablative (n=81) and reduced intensity (n=35). Donors were HLA-matched (n=99) and mismatched (n=17), and related (n=48) and unrelated (n=68). Graft sources were bone marrow (n=89), peripheral blood (n=18) and cord blood (n=9). Graft-versus-host disease (GVHD) prophylaxis consisted of a combination of short-term methotrexate and tacrolimus (n=66) or cyclosporine (n=50). The incidence of grade II-IV acute GVHD was 22%, and that of chronic GVHD was 49%. The median SF level was 911 (range, 14–10, 500) ng/ml, and 49 patients (42%) had hyperferritinemia (HF) (SF>1000 ng/ml). The median time from HSCT to SF assessment was 1276 (range, 134–4213) days, and was similar between patients with and without HF. No significant correlation was found between HF and the presence of cGVHD (p=0.48). There was a moderate correlation between SF level and the number of packed red blood cell units transfused from the diagnosis of underlying disease (ρ=0.69, p Conclusion: At first, we assume that SF after AHSCT is affected by alloimmune reaction and infection and SF could not be used for precise monitoring of IO. However, the current study demonstrated that SF was well correlated with NTBI and that SF can be used for monitoring IO after AHSCT. Humans do not have any physiological mechanisms to excrete excess iron, and the current study showed that many long-term survivors after AHSCT, independently of RBC transfusion, had HF and high NTBI levels. It suggested that IO is a common feature after AHSCT. HF is an independent risk factor for abnormal LFTs in AHSCT survivors as well as diabetes to a lesser extent. These results prompt us to further evaluate the benefit of iron chelating therapy or phlebotomy for patients who suffer from liver dysfunction or diabetes. Disclosures: Sasaki: Novartis Pharma K. K.: Research Funding. Kohgo: Novartis Pharma K. K.: Research Funding.

A noncontact self-running ultrasonically levitated two-dimensional (2D) stage is discussed. The proposed 2D stage was fabricated from a rectangular aluminum plate and four vibrating plates were integrated. The vibrating plates are cantilever-type plates and piezoelectric zirconate titanate (PZT) elements are attached on their fixed ends. To isolate the performance of each vibrating plate, the four vibrating plates have different lengths of 27, 28, 29, and 30 mm. The 2D stage could be levitated at several frequencies from 60 to 80 kHz. The stage could move in the negative x-direction at 71 kHz, at which the flexural vibration mode was excited on the 30-mm-long vibrating plate. Likewise, the stage could move in the negative y-, positive x-, and positive y-directions at 72, 74, and 77 kHz with the flexural vibration mode on the 29-, 28-, and 27-mm-long vibration plates, respectively. A maximum thrust of 6.3 mN could be obtained at 74 kHz with 70 Vpp.

Ultrasonic linear motors with a small body are highly demanded since efficiency does not decrease very much with downsizing. In this study, we aim at realizing ultrasonic linear motor with the diameter less than 10 mm as an alternative to small air cylinder actuators. We propose a new stator structure using two PZT elements between two parallel bending bars. The PZT elements are bonded at the position of several mm from the bar end. In this structure, both bar ends vibrate resonantly in a bending mode, and high vibration displacement amplitude can be obtained along the bars. The length between the PZT element and the bar end determines the optimum driving frequency. The slider simply consists of three metal plates, which sandwich the bending bars, and the preload can be controlled by springs. The conditions in which the traveling wave can be generated along the bars were investigated. When the bars vibrate in a symmetric mode and traveling waves are generated, the slider moves in the direction to the opposite of traveling wave. Traveling wave could be generated by controlling the driving phase difference between the two PZT elements. It was found that the phase differences depend on the distance between the two PZT elements. We experimentally achieved the stroke of 10 mm and the thrust of 78 mN at 23 kHz.

A new technique to destroy the gas‐filled capsule is proposed, making use of the collapsing bubble near the capsule in the ultrasound field. At the moment of collapses under the ultrasound irradiation, the bubble causes flow and acoustic wave radiation. These phenomena are expected to assist the destruction of the capsule. We observed the effect of the bubble on this destruction, using a high‐speed video camera which enables the real‐time imaging. In this experiment, we use gas‐filled capsule made of polyvinyl chloride. When no bubble was near the capsule at sound pressure of 60kPa, the capsule showed no vibration. However, in the presence of neighboring bubble, the capsule showed the destruction behavior of the deformation and the emission of internal gas. At higher sound pressure such as over 100kPa, the capsule showed above destruction behavior even if the bubble was not located near the capsule. In the presence of the bubble, however, the capsule was destructed in a shorter time. These experimental results give significant knowledge to a technique manipulating the gas‐filled capsule destruction in the drug delivery system.

We propose a novel ultrasonic imaging technique by transmitting ultrasonic pulse of dual‐frequency and receiving multifrequency echoes from the biological tissues. When the ultrasonic pulse of two frequencies is transmitted from a transducer, the secondary waves are generated during the nonlinear propagation through the biological media. A choice of f0 and 4f0 as the dual‐frequency results in the generation of 2f0, 3f0, and 5f0 components as the secondary waves. Multifrequency echoes are capable of improving the image quality by reducing the speckle noise. We have developed the following annular type transducer. The PZT disk of 7 mm in diameter is coaxially arranged in the PZT ring of 9 mm in inner diameter and 17 mm in outer diameter. The ring and circular transducers transmit the pulses of 2 and 8 MHz, respectively. It was confirmed that this transducer formed the ultrasonic beams of 4, 6, and 10 MHz as well as the beams of 2 and 8 MHz in degassed water. Then the experiments of imaging the agar‐gel phan...

This paper describes a low‐profile miniature ultrasonic pump consisting of a disk‐bending vibrator and a pipe‐end located vertically to the disk center via a small gap. First, we explored the relationships between the pump performance and the geometrical conditions of the pump experimentally: the pipe diameter, the gap, and vibration distributions. Based on those results, the thickness distribution of the bending disk was designed using finite‐element simulations so that the vibration distribution near the pipe might become uniform. Maximum pump pressure of 20.6 kPa was obtained with a 30‐mm‐diam bending disk and electrical power consumption of 3.8 W. For optimization, we constructed a model of the pump operation in this study. Nonlinearity in the elastic constant of the working fluid was introduced into the model because the temporal change rate of the gap caused by the ultrasonic vibration of the disk vibrator considerably affects the pump’s pressure generation. Results show that the calculated pump pressure well simulates the measured dependence of the gap on the pressure. The acoustic pressure was measured using a fiber optic pressure probe and was compared to the calculated pressure value.

An ultrasonic linear motor using ridge‐mode traveling waves on a substrate is proposed for precision positioning. In our experiments, two parallel ridges are machined on an alumina ceramic substrate with the spacing of 19 mm. The width, height, and length of the ridge are 3 mm, 9 mm, and 186 mm, respectively. Two piezoelectric elements, 19 mm in length and 5×5 mm2 in cross section, were installed at the position of 15 mm from each end of the ridge, and excited at 87.136 kHz in their fundamental longitudinal mode to stimulate the fundamental ridge mode. Elliptical particle motions are formed, due to traveling waves along the ridge waveguides by the phased drive of the two transducers. An alumina ceramic slider pressed to the two waveguides is moved at 13 mm/s in the opposite direction to the traveling wave through the friction forces. The moving direction can be switched by changing the propagation direction of the traveling wave. The detailed characteristics are experimentally studied.

Polyurea thin film exhibits useful characteristics as a high‐frequency ultrasonic transducer such as a low acoustic impedance of 70% of that of PVDF, considerably high piezoelectric constants compatible with conventional piezoelectric polymers, and a higher Curie temperature. A polyurea thin film transducer working at over 100 MHz can be made on any surfaces through vapor deposition polymerization with a high controllability of thickness. To enhance the transducer performance, a multilayered configuration is studied in this study. A special twin‐vacuum‐chamber is used for laminating the polyurea layers and the aluminum electrodes alternately. We fabricate two‐ and three‐layered transducers with 1.5‐μm polyurea thin films as well as single‐layer transducers. To evaluate the transducer performances, we measure the capacitances, the electrical admittances, the coupling factors, and the Q values. The pulse/echo measurements are also conducted to determine the transmission and receiving characteristics of the ...

A method to measure micro liquid volume less than 300 ln with the accuracy of 0.1% is highly needed in biogenetic and biochemical industries. The authors propose a novel method to estimate micro liquid volume in a small well using acoustic resonance. In our experiments, liquid is in a container 6.5 mm in inner diameter and 9 mm in height, and the sound pressure near the well is measured by sweeping the illuminating sound field from 6 to 11 kHz. According to the relationship between the resonance frequency and the volume, we can successfully estimate the small volume with the accuracy of 0.1% and an excellent repeatability. For simultaneous multipoint measurements, we experimentally investigate the effect of adjacent wells on resonant frequency of the target well. It is revealed that the resonance frequency shift due to the mutual coupling between the adjacent wells is negligible if the well interval is less than 5 mm.

The destruction of microcapsules having an elastic thin shell is discussed. An optical observation of the capsule destruction using a high-speed video camera is carried out. As the driving pressure is increased, the microcapsules trapped at the antinode of an acoustic standing wave show circling movements, and then the microcapsules eventually collapse. At the moment of destruction, it is found that the microcapsules change in shape and the internal gas jets out of the capsule rapidly. The sound pressure threshold for the capsule destruction is the lowest under the resonant condition. The capsule destruction also depends on the existence of free bubbles in the surrounding media. It is found that the mechanism of capsule destruction can be categorized into two types: one is due to the increasing driving sound pressure and the other is due to the existence of the free bubbles in the surrounding media. It is considered that the destructions of multicapsules depend on some parameters; however, these two types of capsule destruction are dominant factors.

In the finite element approximation of the exterior Helmholtz problem, we propose an approximation method to implement the DtN mapping formulated as a pseudo-differential operator on a computational artificial boundary. The method is then combined with the fictitious domain method. Our method directly gives an approximation matrix for the sesqui-linear form for the DtN mapping. The eigenvalues of the approximation matrix are simplified to a closed form and can be computed efficiently by using a continued fraction formula. Solution outside the computational domain and the far-field solution can also be computed efficiently by expressing them as operations of pseudo-differential operators. An inner artificial DtN boundary condition is also implemented by our method. We prove the convergence of the solution of our method and compare the performance with the standard finite element approximation based on the Fourier series expansion of the DtN operator. The efficiency of our method is demonstrated through numerical examples.