Modeling And Theoretical Characterization Of Circular pMUT For Immersion Applications.

This paper reported modeling and theoretical characterization of circular piezoelectric micromachined ultrasonic transducer (pMUT) for immersion applications

Theoretical Characterization Of Square Piezoelectric Micro Ultrasonic Transducer For Underwater Applications.

There are numerous advantages of employing MEMS based transducer within underwater applications. This work utilized MEMS based acoustic transducer for underwater applications

Fabrication and characterization of flame retardant 4 and polydimethylsiloxane as substrates for a label-free DNA sensor / Irni Hamiza Hamzah, Emilia Noorsal, Mohammad Nizam Ibrahim, Asrulnizam Abd Manaf and Othman Sidek

Silicon, glass, and ceramic are commonly used base substrates for gold (Au) deposition on label-free DNA biosensors. This study aimed to investigate the suitability of applying flame retardant 4 (FR4) as a base substrate and polydimethylsiloxane (PDMS) as a coating substrate. A thermal evaporator was used to fabricate copper/nickel/Au metals and ensure even deposition of Au throughout FR4. UV exposure soft lithography and wet etching were applied to develop a three-electrode pattern on the metals fabricated on FR4. A simple and straightforward technique on PDMS–FR4 bonding was proved to work at the shear strength of 55 kPa. A cyclic voltammetry (CV) method was performed using the fabricated FR4 sensor to analyze bare Au, DNA immobilization and hybridization. The FR4-based Au fabricated with PDMS acted as a coating layer between terminals and sensing electrodes, and can thus be used as a label-free DNA sensor

A Tunable Ferrofluid-based Polydimethylsiloxane (PDMS) Microchannel Inductor for Ultra High Frequency Applications

In this work, a tunable ferrofluid-based polydimethylsiloxane (PDMS) microchannel inductor with high quality factor and high tuning range is proposed. For this project, PDMS is used to create a microchannel with a width and height of 0.53 mm and 0.2 mm respectively. The microchannel is then used to cover the whole design of a solenoid inductor. A solenoid inductor is designed using wire bonding technique where lines of copper and bond wires are used to form a solenoid winding on top of silicon substrate. A light hydrocarbon based ferrofluid EMG 901 660 mT with high permeability of 5.4 is used. The ferrofluid-based liquid is injected into the channel to enhance the performance of a quality factor. A 3D full-wave electromagnetic fields tool, ANSYS HFSS is used in this work to simulate the solenoid inductor. The results obtained in this work gives a quality factor of more than 10 at a frequency range of 300 MHz to 3.3 GHz (Ultra High Frequency range). The highest quality factor is 37 which occurs at a frequency of 1.5 GHz, provides a high tuning range of 112%

Modeling and simulation of artificial hair cell sensor for underwater applications

This article uses finite volume and finite element methods for optimization of the artificial hair cell sensor. The performance of the sensor was investigated for different materials such as sicon and polysilicon and by varying hair cell dimensions including width and length. The silicon material which has low young modulus was proposed based on the simulation performance. The performance of the hair cell sensor was achieved by increasing the hair cell length while increasing the width did not significantly influence the performance. The performance of the sensor was studied for its viscous force, deflection, von mises stress and sensitivity. From the simulation, the hair cell with a length of 1600 μm and 80 μm width was suggested for the subsequent analysis. Another way to improve the performance was by modifying the hair cell geometry and it was proved that the modified hair cell was more sensitive, based on the deflection. The angle of flow that hit the hair cell also affected the deflection of the sensor where the zero angle flow which was parallel to the substrate was the most effective angle. The limitations of the performance of hair cell for various fluid velocity were also discussed in this paper

The Effect of Nanowire Gap for Silicon Nanowire Transistor to the Current-Voltage (I-Vds)

One-dimensional structures are attracting a lot of attention for optimizing applications as one of the most sensitive devices. Among the fabricated devices, silicon nanowires (SiNW) and silicon nanowire transistors (SiNWT) are of particular importance for promising applications fabricated using bottom-up or top-down approaches to nanoscale devices. In this paper, the sensitivity of the current-voltage characteristic to the nanowire gap of a silicon nanowire transistor (SiNWT) was analyzed. SiNWTs with different nanowire gaps were fabricated using scanning probe microscopy by local anodic oxidation (LOA). Varies gaps can be occurring during the fabrication processes and its can be controlled by RASTER programming in LAO. These gaps can give different results of the sensitivity to the volt-ampere response. However, these gaps can be neglected depending on the subject of the studies and important to the other study, especially in nano particle sensors. In this experiment, the nanowires gaps were developed in the range of 100.5-435.6 nm and had been plotted the measurement data with the volt-ampere response. The data was analyzed using a semiconductor analyzer connected to a HP 4156C SPA series software analysis model from Desert Cryogenics. From the results had been measured the Current-Voltage (IV) increases proportionally with the nanowire gap distance in the SINWT device and these results will give significant effects to the application in nanoparticle sensors

Direct Brain Cooling in Treating Severe Traumatic Head Injury

There are scientific evidences that hypothermia provides a strong neuroprotective effect on the brain following traumatic insults. In this chapter, we describe the pathophysiology of severe head injury with emphasis on benefits of hypothermia. To support these hypothetical or theoretical benefits, we describe our previous study with very encouraging findings done on severe head injuries, treated with direct focal brain cooling, and monitored with intracranial pressure, cerebral perfusion pressure, brain oxygenation, and brain temperature. This chapter ends with our current and still ongoing study in which one of its main objectives is to innovate a direct focal brain cooling machine. This chapter briefly explains the technical part of this cooling machine

Three-dimensional soft material micropatterning via grayscale photolithography for improved hydrophobicity of Polydimethylsiloxane (PDMS)

: In this present work, we aim to improve the hydrophobicity of a polydimethylsiloxane (PDMS) surface. Various heights of 3D PDMS micropillars were fabricated via grayscale photolithog�raphy, and improved wettability was investigated. Two approaches of PDMS replication were demonstrated, both using a single master mold to obtain the micropillar arrays. The different heights of fabricated PDMS micropillars were characterized by scanning electron microscopy (SEM) and a surface profiler. The surface hydrophobicity was characterized by measuring the water contact angles. The fabrication of PDMS micropillar arrays was shown to be effective in modifying the contact angles of pure water droplets with the highest 157.3-degree water contact angle achieved by implementing a single mask grayscale lithography technique

A comparative modelling study of new robust packaging technology 1mm2 VCSEL packages and their mechanical stress properties

Face recognition is one of the most sophisticated disciplines of biometric systems. The use of VCSEL in automotive applications is one of the most recent advances. The existing VCSEL package with a diffuser on top of a lens intended for automotive applications could not satisfy the criteria of the automotive TS16949: 2009 specification because the package was harmed and developed a lens fracture during 100 thermal cycle tests. In order to complete a cycle, the temperature rises from −40 °C to 150 °C and then rises again from 150 °C to 260 °C. The package then needs to be tested 500 times to ensure it fits the requirements without failing in terms of appearance or functionality. To this extent, the goal of this research is to develop packaging for 1 mm2 VCSEL chips with a diffuser on top that prevents fractures or damage to the package during heat cycle testing with multiple materials. The package was created using the applications SolidWorks 2017 and AutoCAD Mechanical 2017. The ANSYS Mechanical Structural FEA Analysis program simulated all packages for mechanical stress to guarantee that all packages generated were resilient to high temperature conditions. All packages exhibit no abnormalities and are robust for various temperatures ranging from low to high. Therefore, these packaged 1 mm2 VCSEL chips with a diffuser on top provide an effective approach for the application of VCSEL suitable in high temperature conditions