Intan Helina Hasan

Printability and structural analysis of Yttrium iron garnet thick film with low firing temperature

This paper presents results of study on Yttrium iron garnet (YIG) thick film paste using linseed oil as organic binder. YIG nanopowder is mixed with organic vehicle which consists of linseed oil, m-xylene and α-terpineol. Samples with different ratios of compositions are prepared to study the printability and adhesion properties of the paste. Paste samples were then screen printed onto alumina substrate, dried and fired at 300°C. Microscopic images of the samples were observed to determine most suitable ratio for producing YIG paste. Based on the results, YIG paste with 30 wt% ratio showed good adhesion to the substrate as well as having high dielectric property compared to pastes with lower powder ratio.

Dielectric properties of ceramic materials obtained from rice husk for electronic applications

This paper reports on dielectric properties of ceramic material obtained from Rice Husk (RH) for electronic applications. RH is considered as agriculture waste material, contains 20–25wt% of silica (SiO2). The nanometer-sized silica powder was prepared via mechanical alloying and subsequent molding into pellet form. The compacted pellet samples were sintered at 800°C, 1000°C, 1100°C and 1200 °C respectively. Silver paste was applied on both faces of the pellet to act as electrodes. For analysis of ferroelectric polarization with respect to electric field, measurement was done using ferroelectric hysteresis loop towards the sintered pellets. The dielectric analysis was done using LCR meter. It clearly shows that dielectric constant of the samples decrease with increasing applied frequency. The capacitance is found to be decreasing with increased sintering temperatures. The result showed that WHRA does contain silica which has high dielectric constant and therefore is suitable for electronics application.

Yttrium iron garnet thick film inclusion for enhanced microstrip patch antenna performance

The present investigation deals with the fabrication of silver (Ag) patch antenna with yttrium iron garnet (YIG) thick film layer inclusion as substrate overlay to enhance its performance. In this paper, YIG nanopowder was mixed with organic vehicle which consists of linseed oil, m-xylene and α-terpineol with powder ratio of 30 wt%. Then the mix was stirred at 150rpm for 3 hours at 40°C in order to obtain homogenous paste, followed by printing it onto FR4 substrate using the screen printing technique to form the YIG thick film layer before dried at 200°C. A basic square shape patch antenna by using silver paste was printed onto the YIG layer and then compared with another patch antenna which was printed without the YIG layer. The results shown that the antenna with YIG thick film layer has return loss of −19.67dB, resonant frequency 6.42GHz, bandwidth 3.13 and Q factor of 2.051, which is better compared to the antenna without the layer by 138.13%, 3.22%, 49.76% and 31.08% respectively.

Silicon nanowire interface circuit for biosensing applications

Detection and quantification of biological and chemical species are critical to many areas of the life sciences and health care, from disease diagnosis to drug screening. Central to detection is the transduction of the signal associated with the sensing event. Advances in nanotechnology have led to the development of the silicon nanowire which is faster, smaller, greener and cheaper. These nanowires have a very narrow diameter similar to that of the chemical and biological species to be sensed making them perfectly suited for biosensing. The top-down fabricated silicon nanowires is used in this work due to its oxide-coated surface and ease of integration with other microelectronic components. Due to the ultra-small output signal of the nanowire, bulky equipments which are often time consuming and expensive are used for reading the signal. This work attempts to build a circuit that can be interfaced with the nanowire to make the signal readable hence the sensor will become portable thereby increasing its utility to being a point-of-care and field-testing device.

Synthesis of carbon nanotubes using microwave oven

Advances in the synthesis of carbon nanotubes (CNTs) have emerged as a result of the properties and potential application of carbon nanotubes. We demonstrated a simple approach of using domestic microwave oven with 600W at 2.45 GHz which was modified to produce CNTs from a carbon source on coated silicon oxide substrate. The Raman spectroscopy showed the graphitic nature of the obtained CNTs, with intensity ratio ID/IG calculated to be 0.92. Field emission scanning electron microscope (FESEM) reveals CNTs are produced on the substrate surface with outer diameter range of 11-44 nm and length of about 0.25 μm. HRTEM further confirmed the graphitic nature of the CNTs obtained. The purity of the nanotubes was analyzed with energy dispersive x-ray (EDX) which showed atomic weight of 98% carbon purity. This paper shows that domestic microwave oven can be used to synthesize CNTs with polymer as the carbon source via plasma catalytic decomposition which was found to be fast, economical and clean technique.