C. Hruanun

A silicon nitride ISFET based immunosensor for Ag85B detection of tuberculosis

A silicon nitride Ion Sensitive Field Effect Transistor (ISFET) based immunosensor was developed as a low-cost and label-free electrical detection for the detection of antigen 85 complex B (Ag85B). The sensing membrane of the ISFET was modified with 3-aminopropyltriethoxysilane (APTES) followed by glutaraldehyde (GA), yielding an aldehyde-terminated surface. This group is available for immobilization of a monoclonal antibody against a recombinant Ag85B protein (anti-Ag85B antibody). The optimal concentration for anti-Ag85B antibody immobilization onto the modified ISFET was 100 μg ml-1. This optimal condition provided the maximal binding capability and minimal non-specific background signal. The binding event between the recombinant Ag85B antigen and anti-Ag85B antibody on the ISFET surface is presented by monitoring the gate potential change at a constant drain current. The dose response for the recombinant Ag85B protein showed a linear response between 0.12 and 1 μg ml-1 without significant interference from other recombinant proteins. The analytical imprecision (CV%) and accuracy of this Ag85B protein biosensor were 9.73-10.99% and 95.29%, respectively. In addition, an irrelevant antibody and other recombinant proteins were employed as a negative control to demonstrate the non-specific interaction of the antigen and antibody. The success of this immunosensor system for Ag85B protein detection facilitates the construction of a promising device which can shorten the turnaround time for the diagnosis of tuberculosis compared to a standard culture method. Furthermore, this device could also be applied for real-time growth monitoring of Mycobacterium tuberculosis in a mycobacterial culture system.

Oxygen Control on Nanocrystal-AlON Films by Reactive Gas-Timing Technique R.F. Magnetron Sputtering and Annealing Effect

The AlON films grown on Si(100) substrates by using radio frequency (r.f.) magnetron sputtering from high purity aluminum (99.999% Al) target with a novel reactive gas-timing technique. The 100 nm thick of AlON films were deposited with 200 watts r.f. power and the substrate temperature is maintained at room temperature by the technique of gas-timing which varying flow-in sequence of high purity of Ar (99.999%) and N2 (99.9999%) gases fed into the sputtering chamber at 10:90 (sec) ratio. The composition and crystal orientation of AlON films affected by gas-timing of Ar and N2 were analyzed by Auger Electron Spectroscopy (AES) and X-ray diffraction (XRD). The oxygen atoms revealed by AES formed into a corporation in films was studied. This suggests that the oxygen contamination formed as AlOXNY compound may due to the residual oxygen in base pressure of 10-7 mbar and higher reactivity of oxygen in the reactor compared to nitrogen. The gas-timing technique used in the sputtering growth system shows the advantage of the oxygen quantity control, while the general sputtering process (without gas-timing technique) shows an increase of the oxygen composition depended on film thickness. The characterizations results clearly indicate that the gas-timing r.f. magnetron sputtering technique plays an important role to control the incorporation of oxygen and to form the nanocrystal-aluminum oxynitride films which very attractive for various sensors applications.

Chemical Characterization and Electrical Properties of Indium Oxynitride Grown by Reactive Gas-Timing RF Magnetron Sputtering

This work investigates changes in the chemical composition of InON thin films, grown by reactive gas-timing rf magnetron sputtering with different O2:N2 timing ratio characterized by Auger Electron Microscope (AES), Raman Spectroscopy which are well correlated with the electrical properties of films. The existence of nitrogen and oxygen in the deposited InON thin films was revealed by AES. Two Raman active optical phonons have been clearly observed and assigned to InN E1(TO) at ~470 cm-1 and E1(LO) at ~570 cm-1 and also shifted with different O2:N2 timing ratio. The carrier mobility of InON thin films was decreased when the ratio of O2:N2 timing is increased.

On-Chip Platinum Micro-Heater with Platinum Temperature Sensor for A Fully Integrated Disposable PCR Module

The on-chip platinum micro-heater prototypes for thermal cycling equipped with platinum temperature sensor are fabricated. The device has been designed, fabricated and characterized to explore the feasibility of the micro-heater for a fully integrated disposable lab-on-a-chip with the PCR module. The on-chip micro-heater demonstrates that the temperature transitions are shorter by comparison with the conventional PCR temperature routines.

Application of Double Gate Ion Sensitive Field Effect Transistor for Detection of Fluid Flow Rate in Micro-Channel

In this work a micro flow sensor, using a double gate Ion Sensitive Field Effect Transistor (ISFET) and two metal electrodes, for fluid flow rate measurement in micro-channels were fabricated and demonstrated. By the channel fabrication the molds were patterned reversely on a silicon wafer using Deep Reactive Ion Etcher (DRIE). The double gate ISFET and two metal electrodes were placed on the mold in the distance 15 millimeters. The channels were formed using polydimethylsiloxane (PDMS) from the mold with the width 1000 and 2000 micrometer and the depth of 250 micrometer. After removing PDMS from the mold the channel was bonded with glass substrate by RF plasma technique. By the verification of flow sensors working range water and one mole of sodium nitrate solution were alternated in flow channel. The fluid flow rate were compared with the flow rate from weighing. It found from the comparison that the high deviation was found at low flow rate. Furthermore, the deviation depends also on the dimension of the flow channel.

A Disposable Polydimethylsiloxane Microdevice for DNA Amplification

In this study, we demonstrate the disposable polydimethylsiloxane (PDMS) microchip provided for DNA amplification. The device consists of two main parts. The first part is PDMS/glass stationary chamber, the other part is a temperature-control microdevice on SiO2/Si substrate. This device consists of a thin film Pt-microheater and a Pt-temperature sensor, which were fabricated with CMOS compatible process. The performance of the device in the DNA amplification shows that, with 10 μl of PCR mixture volume, the approximately 700 bp DNA were successfully amplified within 50 minutes by 30 PCR cycles. The amplified products were comparable with those of a conventional method using electrophoresis. The PCR chip is also suitable for mass production.

Design and fabrication of diffractive phase element for minimizing the focusing spot size beyond diffraction limit

This paper proposes a fabrication apparatus of high numerical aperture (NA) diffractive lens (Concentric Chirped Grating, CCG). The fabrication scheme is based on photolithography incorporating with Double Patterning (DP) technique and Litho-Etch-Litho-Etch (LELE) process. The CCG element having NA up to 1.4 in a glass substrate (n=1.5) at 940 nm wavelength and feature size down to 320 nm is successfully fabricated. The fabricated element can be very useful in integrated Surface Plasmon sensors and beam shaping applications. When controlling the shift between the odd and even rings during the second exposure, the novel phase element that can minimize the optical beam spot size beyond the diffraction limit is generated.

P-buried region effects on breakdown voltage of NPT-TIGBT structure

In this paper, we introduced a P-buried (Pb) layer under trench gate which relieved the electric field crowding in the Non Punch Through Trench gate Insulated Gate Bipolar Transistor (NPT-TIGBT) structure. The Pb layer, with carrier concentration of 5×1016 cm−3, was created underneath the trench gate within the n-drift layer. In this way, the concentration of electric field at the trench bottom corner decreased. As a result, the forward breakdown voltage characteristics of NPT-TIGBT improved. The structures were proposed and verified by T-CAD Sentuarus simulation. From the simulation results, the forward breakdown voltage increased by approximately 25% compared with conventional NPT-TIGBT. Furthermore, the forward current did not degrade the on-state voltage drop. In the experiments, the Pb layer was formed by boron implantation energies above 1 MeV with the Varian Genus 1520 High Energy Ion Implanter. The doping profiles were measured and analysed by SIMS.

An Effect of Viscosity of Coating Materials on Silicon Micro-Patterning Arrays for Superhydrophobic Surface

Two different viscous coating materials, which are Polydimethylsiloxane (PDMS) mixed with 10%wt of Dicumylperoxide (DCP), and Semifluorinate Silane (SFS), were applied to silicon micro-asperity. The cosine’s Young and viscosity of those coating materials are -0.3584uf0b0,-0.3496uf0b0 and 3.176x10-3, 1.339 x10-3 Pauf0d7s, respectively. The rough surfaces with nine asperity shapes were studied. The results shown that, pillar shape has an effect on water contact angle (WCA): Stripe asperity cannot make the average WCA greater than 150uf0b0. When consider the pillar asperity, the WCA falls between 152uf0b0 and 157uf0b0, which exhibits a superhydrophobic surface property. However, actual WCA of the micro-asperity coated with PDMS+10%wt of DCP is lower than that coated with SFS around 1uf0b0 to 7uf0b0. High viscous material makes the asperity size bigger than the design and decreases the WCA: the low viscous material is more suitable for coating on the asperities.

The Optimization of TiN Film Deposited by DC Magnetron Sputtering Provided for Al Diffusion Barrier

Titanium nitride (TiN) film has been widely used as a diffusion barrier layer for VLSI contact metallization because TiN is an excellent barrier against inter-diffusion between Al and Si substrate or silicide. In this work, we studied the properties of TiN films deposited by DC magnetron sputtering with varying N2:Ar flow rate ratio in order to optimize growth conditions and film properties provided for Al diffusion barrier purpose. The TiN films were deposited at the constant pressure level and sputtering time. The crystalline orientation, composition and electrical properties of deposited TiN films were characterized by XRD, AES-depth profile and Four Point Probe measurement, respectively. The XRD results show that the deposited TiN film has two preferred orientations of TiN(111) and TiN(200) planes. The highest intensity of the TiN(111) plane was obtained when the N2:Ar flow rate ratio was 3:1. The electrical resistivity was increased when the N2:Ar flow rate ratio was decreased. The minimum electrical resistivity is 127.8 μΩ-cm when the N2:Ar flow rate ratio is 3:1.