Search

This study aims to report the design of high-performance piezoelectric MEMS energy harvesters using a full batch MEMS-fabrication process with a Si proof mass and multilayered Pb(Zr,Ti)O3 (PZT) thin films without bonding of a proof mass and/or bulk piezoelectric ceramics. These devices contain sputtered multilayered PZT thin films with internal metal electrodes as a thick energy-conversion layer. The thickening of the piezoelectric layer by multilayer sputter deposition technique enabled the batch fabrication of high-performance piezoelectric MEMS harvesters. These fabricated device with the footprint of 10 × 10 mm2 was found to provide a high output power of 53.7 μW per gravitational acceleration. These results are expected to be useful for the future development of alternatives to batteries for autonomous sensor systems.

Pro-inflammatory cytokines are released in septic shock and impair cardiac function via the Jak-STAT pathway. It is well known that sympathetic stimulation leads to coupling of the β-adrenergic receptor/Gs/adenylyl cyclase, a membrane-bound enzyme that catalyzes the conversion of ATP to cAMP, thereby stimulating protein kinase A (PKA) and ultimately compensating for cardiac dysfunction. The mechanism of such compensation by catecholamine has been traditionally understood as PKA-mediated enforcement of cardiac contractility. We hypothesized that exchange protein activated by cyclic AMP (Epac), a new target of cAMP signaling that functions independently of protein kinase A, also plays a key role in protection against acute stresses or changes in hemodynamic overload. Lipopolysaccharide injection induced cytokine release and severe cardiac dysfunction in mouse. In mouse overexpressing Epac1 in the heart, however, the magnitude of such dysfunction was significantly smaller. Epac1 overexpression inhibited the Jak-STAT pathway, as indicated by decreased phosphorylation of STAT3 and increased SOCS3 expression, with subsequent inhibition of iNOS expression. In cultured cardiomyocytes treated with isoproterenol or forskolin, the increase of SOCS3 expression was blunted when Epac1 or PKCα was silenced with siRNA. Activation of the cAMP/Epac/PKCα pathway protected the heart against cytokine-induced cardiac dysfunction, suggesting a new role of catecholamine signaling in compensating for cardiac dysfunction in heart failure. Epac1 and its downstream pathways may be novel targets for treating cardiac dysfunction in endotoxemia.

Type 5 adenylyl cyclase (AC5) plays an important role in the development of chronic catecholamine stress-induced heart failure and arrhythmia in mice. Epac (exchange protein activated by cAMP), which is directly activated by cAMP independent of protein kinase A, has been recently identified as a novel mediator of cAMP signaling in the heart. However, the role of Epac in AC5-mediated cardiac dysfunction and arrhythmias remains poorly understood. We therefore generated AC5 transgenic mice (AC5TG) with selective disruption of the Epac1 gene (AC5TG-Epac1KO), and compared their phenotypes with those of AC5TG after chronic isoproterenol (ISO) infusion. Decreased cardiac function as well as increased susceptibility to pacing-induced atrial fibrillation (AF) in response to ISO were significantly attenuated in AC5TG-Epac1KO mice, compared to AC5TG mice. Increased cardiac apoptosis and cardiac fibrosis were also concomitantly attenuated in AC5TG-Epac1KO mice compared to AC5TG mice. These findings indicate that Epac1 plays an important role in AC5-mediated cardiac dysfunction and AF susceptibility.

Myocardial β-adrenergic receptor (β-AR) β1- and β2-subtypes are highly homologous, but play opposite roles in cardiac apoptosis and heart failure, as do cardiac adenylyl cyclase (AC) subtypes 5 (AC5) and 6 (AC6): β1-AR and AC5 promote cardiac remodeling, while β2-AR and AC6 activate cell survival pathways. However, the mechanisms involved remain poorly understood. We hypothesized that AC5 is coupled preferentially to β1-AR rather than β2-AR, and we examined this idea by means of pharmacological and genetic approaches. We found that selective inhibition of AC5 with 2'5'-dideoxyadenosine significantly suppressed cAMP accumulation and cardiac apoptosis induced by selective β1-AR stimulation, but had no effect on cAMP accumulation and cardiac apoptosis in response to selective β2-AR stimulation. The results of selective stimulation of β1-AR and β2-AR in neonatal cardiac myocytes prepared from wild-type and AC5-knockout mice were also consistent with the idea that β1-AR selectively couples with AC5. We believe these results are helpful for understanding the mechanisms underlying the different roles of AR subtypes in healthy and diseased hearts.

In this paper, a design improvement of combination spring that consists of linear resonator and curved beam for nonlinear vibration energy harvesting is described. The intrinsic curved beam for snap-through buckling acts as mechanical frequency converter (MFC) that applies high frequency acceleration to the linear resonator. We newly designed the parallel curved beams to reduce the force required for snap-through and maximum stress during snap-through behavior. From FEM analyses, the force and the stress are reduced from 35.4 mN to 10 mN and from 350 MPa to 200 MPa, respectively.

In this article, we described concepts for improving the shock reliability of MEMS electrostatic vibration energy harvesters. The harvester is based on silicon mass spring system supporting an electret. We determined experimentally that the primary cause of failure of the harvester under shock excitation is impact between the anchors of the springs. The impact creates chipping damages on the anchors which induces breakage of the springs. The springs are vital for proper functioning of the harvester, so that when they are broken, the device losses all its functionalities. Avoiding impact between moving parts of the harvester is difficultly feasible. However, avoiding impact on vital parts of the device is easily feasible with the use of shock absorbing bumpers. The concept of rigid bumpers is first investigated. While this approach improves the survival chances of the springs under a shock excitation, chipping damages are observed on the rigid bumpers. The residue from the chipping damages may hinder the functionality of the harvester. To limit the chances of chipping damages on the bumpers, flexible in place from rigid bumpers are investigated. By using Hertz contact model approach, it is shown that flexible bumpers allow reducing the risk of chipping damages by a factor five.

This study presents a wafer-level batch fabrication technique of NdFeB film for MEMS (Micro Electromechanical Systems) based electromagnetic type energy harvester. By using 20 μm thickness NdFeB sputtered magnetic film on a trench-etched Si microstructure, fine patterned magnet structures for energy harvester had been realized. However the size of the sputtered sample was limited to the slightly small size. In this study, we improve the sputtering equipment to apply the NdFeB film process on a four-inch Si wafer. The film characteristics, estimation of the compatibility with the MEMS process and also energy harvesting result are presented.

The silicon molding technique is described for patterning of NdFeB/Ta multilayered magnetic films and NdFeB magnetic powder at the micron scale. Silicon trenches are seamlessly filled by 12-μm-thick NdFeB/Ta multilayered magnetic films with a magnetic retentivity of 1.3 T. The topography image and magnetic field distribution image are measured using an atomic force microscope and a magnetic force microscope, respectively. Using a silicon molding technique complemented by a lift-off process, NdFeB magnetic powder is utilized to fabricate magnetic microstructures. Silicon trenches as narrow as 20 μm are filled by a mixture of magnetic powder and wax powder. The B–H hysteresis loop of the patterned magnetic powder is characterized using a vibrating sample magnetometer, which shows a magnetic retentivity of approximately 0.37 T.

Tumor suppressor protein p53, our most critical defense against tumorigenesis, can be made powerless by mechanisms such as mutations and inhibitors. Fortilin, a 172-amino acid polypeptide with potent anti-apoptotic activity, is up-regulated in many human malignancies. However, the exact mechanism by which fortilin exerts its anti-apoptotic activity remains unknown. Here we present significant insight. Fortilin binds specifically to the sequence-specific DNA binding domain of p53. The interaction of fortilin with p53 blocks p53-induced transcriptional activation of Bax. In addition, fortilin, but not a double point mutant of fortilin lacking p53 binding, inhibits p53-dependent apoptosis. Furthermore, cells with wild-type p53 and fortilin, but not cells with wild-type p53 and the double point mutant of fortilin lacking p53 binding, fail to induce Bax gene and apoptosis, leading to the formation of large tumor in athymic mice. Our results suggest that fortilin is a novel p53-interacting molecule and p53 inhibitor and that it is a logical molecular target in cancer therapy.

We investigated alterations between serum interleukin 18 (IL-18) and IL-18 binding protein (18BP) in T2DM patients. 18 BP began to increase after IL-18 increased and reached a threshold, in which case kidney dysfunction would have developed. These data indicate that 18BP might express glomerular dysfunction more closely than IL-18.

Thick silicon dioxide with good heat insulation properties can reduce the parasitic capacitance and heat conductivity in sensors and actuators. This research focuses on the evaluation of the mechanical properties of the silicon dioxide microstructure fabricated by using trench etching and oxidation process in order to use it for movable elements in MEMS devices. The elastic modulus is estimated from the resonant frequency of fabricated cantilevers. It revealed comparable values to that of bulk SiO 2 . Non-linear characteristics such as hardening and softening spring effects are observed dependent on the patterning direction of trench etching.

Low-temperature α-alumina formation was attempted using various polyhydroxoaluminum (PHA)–hydroxy acid composite gels, which were prepared from PHA solutions containing different amounts of hydroxy acids, such as lactic acid, glycolic acid, malic acid, citric acid or mandelic acid. The composite gels began to transform into α-alumina when heated at lower temperatures of around 500 °C and the α-alumina fraction of the heat-treated products increased with increasing temperature. The α-alumina fraction was also dependent on both the type and amount of hydroxy acid additive. Among the composite gels studied, significant low-temperature α-alumina formation was observed for the PHA–mandelic acid, PHA–citric acid and PHA–lactic acid series. Low-temperature α-alumina formation was further promoted by employing a two-step heat-treatment method. The interaction between the functional groups of PHA and hydroxy acid and the seeding effect appear to play important roles in the course of the gelation and calcination processes for low-temperature α-alumina formation.

This study demonstrates the electret type inertial energy harvester for low-frequency vibrations such as human movements. Because a moving mass of the harvester is supported by the very soft spring, the mass collides easily with the frame structure. This collision induces the higher natural frequency vibration to the mass even at the applied vibration frequencies below the natural resonant frequency, which improves the efficiency of the power generation. The fabricated device generated the power of 1.8 nWrms for applied vibration of 20Hz and 200μmp-p with the optimal load resistance of 32 MΩ. The packaged device size is 0.23cm3 and the weight of the moving mass is 122mg.

A lot of energy harvesting devices using electret material has been developed. Since the power from the electret energy harvester is proportional to the surface charge concentration, i.e. charged voltage on the electret, frequency and dynamic range of the capacitance change. To fabricate the electret, the corona discharge is a very popular charging method that consists of a high voltage needle for corona ions generation, and a grid electrode applying a bias voltage that implants the electrons from corona ions to the electret material. In this study, we introduce a novel charging method with fine patterns using the buried gridelectrodes applied with a bias voltage. We also describe FEM analysis and experimental results.

In this paper, we present the concept of a microelectromechanical systems ring laser gyroscope (MEMS-RLG) and its optical components. MEMS-RLG has a semiconductor optical amplifier (SOA) enclosed with mirrors that form an optical loop for an external laser oscillator in free space. To confirm the feasibility of MEMS-RLGs, we constructed an experimental device with commercially available SOA and mirrors for external oscillation. We also show the fabrication and characteristics of optical components such as movable mirrors and a lens-positioning device, which are required for a miniaturized MEMS-RLG.

This paper demonstrates that the Ca-doped alumina nanopowders prepared by a new sol–gel route using polyhydoxoaluminum (PHA) and CaCl 2 solutions under α-alumina seeding represent a viable option for producing fine-grained ceramics. Appropriate conditions for producing Ca-doped alumina nanopowders suitable for low-temperature finer grained densification were 0.10 mol% Ca-doping, 5 mass% α-alumina seeding and a calcination temperature of 900 °C. These conditions led to the formation of new nano-sized alumina powders, which consisted of ∼80 nm α-alumina particles and γ-alumina nanoparticles. Using these Ca-doped nanopowders, fully densified alumina ceramics with a uniform microstructure composed of fine grains with an average grain size of 0.66 μm could be obtained at 1375 °C. Clearly, the Ca-doped nanopowders obtained here through the proposed sol–gel route are very suitable for fabricating dense, fine-grained alumina ceramics because an undoped sample with 5 mass% seeds led to a microstructure with an average grain size of 1.39 μm at 1375 °C.

This paper presents a development and characterization of a novel technology for seedlayer-less gold electroplating. This method allows that a gold film grows directly and selectively on a silicon surface. In the MEMS field, the gold film is increasingly drawing attention for its low electrical resistivity, high physicochemical stability, high biocompatibility and high reflectivity to the infrared ray. Due to low adhesion of the gold, it had been considered that it is difficult to obtain the direct electroplating film on a silicon surface. The two-step gold electroplating method presented here, which contains the first thin electroplating of 0.2 μm with low current density of 0.75 mA/cm 2 and following annealing process at 250 °C for 30 min, achieves increasing adhesion and realizes practical gold film on a silicon.

In this paper, we present an MEMS gyroscope with double gimbal structure. The device has inner- and outer-gimbals with independent coils (inner- and outer-coils), and the gimbals are perpendicularly supported by torsion bars. In the parallel magnetic field, the reference vibration of the inner-gimbal is introduced by electromagnetic force from the inner-coil and displacement of the outer-gimbal by the Coriolis force is detected by electromotive force at the outer-coil. The device has no critical parts such as narrow gaps or comb drivers, and it requires less accurate alignment of the magnetic field. Since the device can operate in atmospheric pressure, a hermetic seal is not required. For stable operation, the device was combined with a semi-digital control circuit. The circuit has an overtone PLL oscillator, time-shared driving/detecting logic, a kind of adaptive band pass filters. The system showed excellent performance for angular rate detection. Additionally, the characteristics of the device operating in vacuum were also examined.

We present design methodology, fabrication process and characterization of a dual-axis MEMS galvano-mirror with double gimbal structure. In the device, soft torsion beams are made of the photosensitive epoxy resin, SU-8, in order to obtain large-deflection angle for small driving power. In this paper, we present characteristics of the inner and outer mirrors for dynamic and static operation, and also test results for stability. The tilt angle of the mirror for applied static current is about 0.1°/mA. Maximum deflection angle at resonant operation was measured to be over than ±40°.

Preconditioning enables endogenous protection to repeated myocardial ischemia. However, the effect of preconditioning on beta1 adrenergic receptor (AR) signal remains controversial. We have recently developed receptor assay system using whole cells, in which overexpressed cell surface beta ARs can be readily quantitated without disrupting the cell. Using this technique, we examined the effects of chemical/metabolic ischemia on the beta1 AR sequestration and adenylyl cyclase activity. Isoproterenol treatment, but not forskolin treatment, of HEK293T cells overexpressing beta1 ARs led to a rapid decrease (within 2 hours) in the number of the cell surface receptor, which was negated in the presence of concanavalin A. Similarly, treatment of cells with potassium cyanide and 2-deoxy-D-glucose (chemical/metabolic ischemia) induced similar receptor sequestration. When isoproterenol was superimposed on chemical/metabolic ischemia, the degree of sequestration became greater. However, when cells were pre-exposed to potassium cyanide on the preceding day (chemical preconditioning), the sequestration induced by either isoproterenol or chemical/metabolic ischemia was attenuated. Adenylyl cyclase catalytic activity as assessed by stimulation with forskolin was decreased by chemical/metabolic ischemia but fully recovered after 24 hours, suggesting that chemical/metabolic ischemia treatment did not alter cell viability. Putting together, chemical/metabolic ischemia induced beta1 AR sequestration in a similar manner to isoproterenol. In addition, preconditioning prevented the beta1 AR sequestration induced by both isoproterenol and chemical/metabolic ischemia. Pre-conditioning may play a role in preserving the cell surface beta ARs by inhibiting the sequestration that is usually induced by an ischemic event or beta adrenergic stimulation.

This paper deals with a monolithically integrated multi-sensor system for the intelligent data carrier (IDC) system. The system includes a three-dimensional accelerometer, pressure sensor, temperature sensor and humidity sensor as well as the peripheral circuitry for each sensor on one chip. The peripheral circuitry was designed to combine them to one-chip microprocessor with A/D converter. The monolithic multi-sensor chip was realized using an SOI wafer, where the Deep-RIE bulk-micromachining process and bipolar IC process were used for sensor device fabrication and circuit fabrication, respectively. The acquired data are logged on a nonvolatile memory and transmitted via TCP/IP protocol on the ethernet by the “embedded Linux board”. We also show the remote monitoring system for multi-environmental sensor by using the graphical software and general purpose web browsing software.

Serological and histological studies were carried out to explore the role of the lectin complement pathway in the pathogenesis of cryoglobulinemic glomerulonephritis. Sixteen patients with mixed cryoglobulinemia type II with glomerulonephritis (GN) were enrolled. All cases had hepatitis C virus (HCV) infection. The serum concentration of mannose-binding lectin (MBL) was significantly higher in the GN patients than in the normal controls according to ELISA (P < 0.01). IgG, IgM, C1q, C4d, HCV envelope antigen, MBL, and MBL-associated serine protease-1 (MASP-1) could be visualized in the cryoprecipitate of the 16 patients by Dot blot assay. Renal biopsy specimens obtained from 3 patients were examined by immunohistochemistry, and the glomeruli strongly stained for IgG, IgM, MBL, MASP-1, C4d, C3c, and C3d in a fringe-like pattern. The pattern of HCV constituent deposition was partially fringe-like. The complement profiles of the 16 cases were distinctive; briefly, the serum levels of C1q, C2, and C3 were reduced, although the levels of circulating regulatory proteins (C1-inhibitor, factor H, and factor I) were in the normal range. The serum C4 level was significantly reduced. These results indicate that immune complex formation involves molecules of the lectin pathway and leads to organ damage in cryoglobulinemic glomerulonephritis.

In this paper, we present the vacuum-sealed vibrating gyroscope using silicon bulk micromachining technology. The size of the device is 12×12×1.4 mm 3 . Two glass substrates hold the silicon sensing part. The sensing part is encircled with the silicon frame which forms hermetic seal with the glass substrates. From the results of initial testing, we obtain an angular rate detection sensitivity of approximately 8.9 μV/(° s −1 ), a nonlinearity of 1.25% FS and a detection resolution of approximately 0.2° s −1 at 1 Hz BW. Additionally, we show the detection characteristics of the two orthogonal components of the applied angular rates simultaneously.

Henoch-Schönlein purpura nephritis (HSPN) is considered a form of systemic vasculitis of the small blood vessels with immune pathogenesis. In this disorder, the complement system is recognized as an important mechanism of glomerular injury. The aim of this study is to determine whether the lectin pathway, a novel pathway of complement activation, is related to the pathogenesis of HSPN. Renal biopsy material from 10 patients with HSPN was studied immunohistochemically and examined for a clinicopathologic correlation. Serum levels of complement components, including mannose-binding lectin (MBL), and plasma levels of complement activation products were also evaluated in these patients and compared with levels in patients with immunoglobulin A (IgA) nephropathy or mesangial proliferative glomerulonephritis (GN) without IgA deposition (non-IgA GN). Glomerular deposition of components of the pathway, MBL and MBL-associated serine protease (MASP-1), as well as C3b/C3c, C5b-9, and C4-binding protein (C4-bp), was detected in 8 of 10 patients. Although no significant correlation was found between glomerular deposition of MBL/MASP-1 and histological or clinical findings, the biopsies on all patients with MBL/MASP-1 deposits were performed within 20 weeks from the onset of disease. Levels of plasma C4d, the activation fragment of C4, and C4-bp, a soluble regulatory protein of the pathway, were greater in patients with HSPN than in those with non-IgA GN. However, there was no difference in serum MBL levels between the three groups of patients (HSPN, IgA nephropathy, and non-IgA GN). These results suggest that complement activation through the lectin pathway was involved at the onset of HSPN, and this mechanism might be important in the disease pathogenesis.

A 44-year-old man developed nephrotic syndrome 9 months after HLA-identical sibling bone marrow transplantation. Membranous changes consisted mainly of alterations of glomeruli, which were interpreted as chronic graft-versus-host disease (GVHD) caused by lodging of the circulating immune complex. In the tubules, a lumpy deposition of IgG and complement breakdown products was distributed along the tubular basement membrane, which coincided with the peculiar deposits ascertained by electron microscopy. These findings suggest that an extraglomerular reaction should be considered in evaluating renal involvement of GVHD.