Elevated gamma glutamyl transferase levels are associated with the location of acute pulmonary embolism. Cross-sectional evaluation in hospital setting

ABSTRACT CONTEXT AND OBJECTIVE: The location of embolism is associated with clinical findings and disease severity in cases of acute pulmonary embolism. The level of gamma-glutamyl transferase increases under oxidative stress-related conditions. In this study, we investigated whether gamma-glutamyl transferase levels could predict the location of pulmonary embolism. DESIGN AND SETTING: Hospital-based cross-sectional study at Cumhuriyet University, Sivas, Turkey. METHODS : 120 patients who were diagnosed with acute pulmonary embolism through computed tomography-assisted pulmonary angiography were evaluated. They were divided into two main groups (proximally and distally located), and subsequently into subgroups according to thrombus localization as follows: first group (thrombus in main pulmonary artery; n = 9); second group (thrombus in main pulmonary artery branches; n = 71); third group (thrombus in pulmonary artery segmental branches; n = 34); and fourth group (thrombus in pulmonary artery subsegmental branches; n = 8). RESULTS : Gamma-glutamyl transferase levels on admission, heart rate, oxygen saturation, right ventricular dilatation/hypokinesia, pulmonary artery systolic pressure and cardiopulmonary resuscitation requirement showed prognostic significance in univariate analysis. The multivariate logistic regression model showed that gamma-glutamyl transferase level on admission (odds ratio, OR = 1.044; 95% confidence interval, CI: 1.011-1.079; P = 0.009) and pulmonary artery systolic pressure (OR = 1.063; 95% CI: 1.005-1.124; P = 0.033) remained independently associated with proximally localized thrombus in pulmonary artery. CONCLUSIONS : The findings revealed a significant association between increased existing embolism load in the pulmonary artery and increased serum gamma-glutamyl transferase levels

A MEMS-based energy harvester for generating energy from non-resonant environmental vibrations

This paper presents a non-resonant vibration based electromagnetic MEMS energy harvester, which generates energy from low frequency vibrations with low displacement amplitude. The harvester is composed of an energy harvester chip, housing two electroplated copper micro coils realized on parylene cantilevers and a miniature NdFeB magnet with two mechanical barrier arms. The structure uses the mechanical frequency up conversion (mFupC) principle for energy generation. The non-resonant operation is maintained by attaching the chip and the magnet to two different platforms, which move with respect to each other. The prototype generates 2.1 mV RMS voltage and 18.5 nW RMS power from both coils on the average, under 10 Hz, 5 mm peak to peak (1 g) external vibrations. The RMS value of the generated voltage during the mFupC duration is calculated as 9.5 mV, leading to 363 nW power and 1.1 mu J energy delivery from each coil to equivalent resistive loads at each occurrence of the mFupC. Serial connection of the coils is also studied and it is concluded that this configuration has a non-significant effect on the generated power since the waveforms of the coil voltages have both phase and resonance frequency differences, canceling out some portion of the signal when they are added together. During the tests, it is observed that excessive stress around the cantilever fixed edges eventually break the coil lines at this region. This is handled by applying an epoxy to this region, lowering the stress on the copper line. With this configuration, the generated power is slightly reduced due to the decreased resonance frequency and increased damping ratio of the cantilevers. The epoxy-applied prototype has been tested under various vibration conditions with no damage on the coil, and the non-resonant operation behavior of the energy harvester has been verified

Orthogonal fluxgate magnetic field sensor

Orthogonal fluxgate sensor for measuring an external magnetic field Hext, comprising a conductor for carrying an excitation current lexc, a ferromagnetic material adapted to saturate in the presence of a magnetic field generated by the excitation current, and at least one pick-up coil adapted to detect variations in the magnetic field in the vicinity of the magnetic material. The excitation conductor comprises a substantially linear elongated portion of conductive, non-magnetic material, forming an excitation rod (6). The magnetic material surrounds the excitation rod in the form of a cladding (8)

A miniature and non-resonant vibration-based energy harvester structure

This paper presents a miniature and non-resonant vibration based electromagnetic (EM) energy harvester, which generates energy from low frequency and low amplitude vibrations. The structure combines a MEMS-based coil realized on a parylene cantilever, and a miniature NdFeB magnet, resulting in a small sized EM harvester prototype with a strong magnetic part. The magnet is attached to a moving platform, whereas the coil is fixed to a stationary base. The mechanical frequency up-conversion (mFupC) technique is utilized to increase the energy conversion efficiency. The fabricated prototype has a volume of 120 mm(3) and generates 1.44 mV RMS voltage and 24 nW RMS power from 10 Hz, 4 mm peak-to-peak (0.8 g) external vibrations. A power density of 200 nW/cm(3) has been realized with the prototype

An orthogonal fluxgate-type magnetic microsensor with electroplated Permalloy core

In this paper, we present a new microfabricated orthogonal fluxgate sensor tructure. The sensor consists of an electroplated copper excitation rod surrounded by an electroplated Permalloy layer and has planar pick-up coils for signal detection. The use of electroplating leads to a low-cost fabrication process and the use of planar pick-up coils provides easy integration with CMOS processes. The fabricated sensor has an excitation independent linear range of ±200uT, a sensitivity of 510 uV/mT, and an average power dissipation of 8.1mW for 100 mA-peak sinusoidal excitation current at 100 kHz frequency. The equivalent magnetic noise is 95 nT/√Hz at 1 Hz, and the RMS noise is 215 nT for 10 Hz bandwidth

A parylene coating based room temperature wafer-level attachment method for MEMS integration with zero applied force

This paper reports a wafer-level attachment method using parylene as an interlayer material for integrating various shaped and fragile substrates into MEMS processes. In the proposed method, the substrates are placed on a handle wafer containing pillars and perforations, and coated with a standard parylene deposition process realized at room temperature, with no applied force. The substrate and the handle wafer are attached to each other via formation of a parylene interlayer. Only poor attachment is observed by utilizing a handle wafer containing pillars alone, as parylene cannot perfectly penetrate through the structures. The parylene penetration is significantly improved by introducing perforations to the handle wafer. It is experimentally shown that, with a perforated handle wafer containing pillar structures having 20 mu m height and 4.5 mm spacing, parylene completely fills the gap between the structures, and can successfully be used to attach substrates to each other. The shear strength between the attached substrates has been measured as 0.49 MPa, proving the feasibility of the method for integrating various materials into MEMS processes. As a demonstrator for the utilization of the attachment method in the microfabrication processes of sensors and actuators, a fragile 7 cm x 7 cm x 190 mu m PZT sheet has been attached to a handle wafer and processed successfully through a sample set of standard MEMS processes

Fluxgate-type magnetic microsensors for wide linear measuring range

In this paper, we present a microfabricated fluxgate sensor for wide linear measuring range applications. The sensor consists of an electroplated copper excitation rod surrounded by an electroplated Permalloy core layer, and has planar pick-up coils for signal detection. Fabricated sensors are tested in orthogonal and parallel operation modes. The effects of operation modes and excitation conditions are compared. A linear operating range of ±900 μT is proved in the orthogonal mode, whereas the same sensor has much lower linear range in the parallel mode. The use of the sensor in a contactless current measurement application is also presented

A parylene coating based room temperature wafer-level attachment method for MEMS integration with zero applied force

This paper reports a wafer-level attachment method using parylene as an interlayer material for integrating various shaped and fragile substrates into MEMS processes. In the proposed method, the substrates are placed on a handle wafer containing pillars and perforations, and coated with a standard parylene deposition process realized at room temperature, with no applied force. The substrate and the handle wafer are attached to each other via formation of a parylene interlayer. Only poor attachment is observed by utilizing a handle wafer containing pillars alone, as parylene cannot perfectly penetrate through the structures. The parylene penetration is significantly improved by introducing perforations to the handle wafer. It is experimentally shown that, with a perforated handle wafer containing pillar structures having 20 mu m height and 4.5 mm spacing, parylene completely fills the gap between the structures, and can successfully be used to attach substrates to each other. The shear strength between the attached substrates has been measured as 0.49 MPa, proving the feasibility of the method for integrating various materials into MEMS processes. As a demonstrator for the utilization of the attachment method in the microfabrication processes of sensors and actuators, a fragile 7 cm x 7 cm x 190 mu m PZT sheet has been attached to a handle wafer and processed successfully through a sample set of standard MEMS processes

Investigation of Giant-Magneto-Impedance (GMI) effect and magnetic hysteresis in microfabricated Permalloy/Coper device

In this paper, we present the giant-magneto-impedance (GMI) effect in a microfabricated closed Permalloy core which surrounds a copper excitation rod. We measured a 90% change in the inductance value of the device for a sinusoidal excitation at 500 kHz in a 4.5mT range. The change in the device resistance is negligible for excitation frequencies below 1 MHz, and goes above 14% for 30 MHz excitation. Magnetic hysteresis of the device inductance is studied and improved by applying periodic “degauss” pulses during measurement, instead of increasing the amplitude of the excitation current or using traditional annealing processes

A ROOM TEMPERATURE, ZERO FORCE, WAFER-LEVEL ATTACHMENT METHOD FOR MEMS INTEGRATION

This paper presents a wafer level attachment method for handling various shaped structures for MEMS processes, using parylene as an interlayer material. In this method, a handle wafer containing pillars and perforations is utilized, and structures are attached to the handle wafer through a parylene coating process realized at room temperature with no applied force. It is observed that pillars with 20 mu m height, 2.5 mm side length, and 4.5 mm spacing can successfully be used to attach two 4 '' substrates to each other. The shear strength between the attached substrates is measured as 0.49 MPa, proving the feasibility of the method for integrating various materials into MEMS processes