Goib Wiranto

Design of online data measurement and automatic sampling system for continuous water quality monitoring

In this research, it has been designed a continuous water quality monitoring system consisting of sensors for measuring Dissolved Oxygen (DO) and pH, data acquisition based on a PCDuino microcontroller, a sample collection unit, and PC based graphical display. The main part of the system is the PCDuino microcontroller, that has a function of controlling the data transmission and the operation of the automatic sampling unit based on comparison of the measured parameter values against certain threshold. The automatic sampling unit was constructed from PVC holder, a 12V motor stepper, a 12V DC pump, and 8 glass tube sample storages. Experimental results showed that when the measured DO value dropped below 5 mg/l, or the pH values below 4 or above 9, the sample collection unit worked by filling up 20 ml sample in just under 650 ms. All the measured data can be displayed on a PC for further analysis. This prototype system is expected to find wide applications in the field of environmental and aquaculture monitoring.

Integrated online water quality monitoring

In this paper the design and realisation of an integrated online water quality monitoring system will be described. The system has been applied specifically to monitor the DO (Dissolved Oxygen) and pH parameters in several shrimp aquaculture centersin Indonesia. The aim was to reduce energy consumption and to create optimum water condition for the shrimp aquaculture.Using an automatic aeration system, the DO value has been maintained above 5 mg/l. On the other hand, data collected from the sensor measurements at each aquaculture can be accessed by SMS gateway or transmitted to the master station using telemetric system for further analysis or study.

A Low-Cost CMOS Reconfigurable Receiver for WiMAX Applications

This paper presents a low cost solution for lower frequency WiMAX CPE receivers. A receiver which consists of wideband LNA, switching mixer, VCO and reconfigurable low-pass filter have been designed and simulated in different WiMAX receive bands such as in the 2.3-GHz band, in the ISM band (2.4-GHz), and in the 2.5-GHz band, as well as in different channel bandwidths, ranging from 1.75 MHz up to 10 MHz. The zero-IF architecture is chosen as it suits for receivers using OFDM signals with null DC subcarrier. The LNA and switching mixer have been fabricated in 0.18 mum RF- CMOS technology and the measurement results show that these building blocks have a combined RF-to-IF gain of 20-dB, a DSB noise figure of 3.5-dB, an RF-to-IF IIP2 and IIP3 higher than +20-dBm and 0-dBm, respectively. The circuit consumes 16-mA from 1.8-V supply and occupies a die area of 0.42 times 0.50 mm2. Simulation results of the negative-Gm VCO show that it can oscillate at the desired frequencies with phase-noise performance of better than - 125-dBc/Hz at a frequency offset of 3.5 MHz. A reconfigurable 4th order of Gm-C low-pass filter (LPF) has been designed using two 2nd order biquad gm- C LPFs and its simulation results show that - 3-dB frequency corners can be adjusted to 1.75-MHz, 3.5-MHz, 7-MHz and 14-MHz. Both VCO and LPF are simulated using 0.18 mum RF-CMOS technology.

Fabrication of SnO2 based CO gas sensor device using thick film technology

This research was aimed at fabricating a CO gas sensor based on SnO2 material synthesized using sol-gel method. The sensor components include thin film gold electrode and a PdAg heater screen printed on the backside of the alumina substrate. The device was tested to study the effect of temperature variation on the resistivity of the heater component, and the response of the SnO2 sensitive layer to 10 ppm CO gas. The SnO2 layer was characterized using SEM and EDS to determine the morphology and composition of the material. It was found that the SnO2 sensitive layer contained 21.21% C atoms, 22.43% O atoms, 14.98% Si atoms, 0.34% Cr atoms, 1.16% Ag atoms, 1.78% Sn atoms, and 38.11% Au atoms. The sensor sensitivity to CO gas increased with increasing temperature. The Operational temperature of this sensor was 95° C with the highest sensitivity value obtained was 16.59.

Design and Fabrication of Thick Film Dissolved Oxygen Sensor Based on RuO2 Working Electrodes for Water Quality Monitoring

A Dissolved Oxygen (DO) sensor has been designed and fabricated on an 8.5 x 22.5 mm Alumina substrate using thick film technology. The structure of the sensor device consisted of AgPd working/counter electrode, Ag/AgCl reference electrode, RuO2 active layer, KCl electrolyte, and TiO2 membrane. Formation of the Ag/AgCl reference electrode was done by chlorination of Ag layer using FeCl3, and the TiO2 membrane was formed by screen printing of TiO2 paste. Measurement was done to study the sensor’s performance based from the current-voltage characteristics between 1.1 – 1.6 V. The results showed that a stable diffusion current was obtained when the input voltage was 1.4 V, resulting in the best sensor performance with a sensitivity of 0.560 μA l/mg and a stable step response time of 4 min. The device showed highly potential to be used as candidate for online water quality monitoring system.

Liquid Conductivity Sensor Based on AgPd Paste Fabricated on an Al2O3 Substrate Using Screen Printing Technique

In this paper, the design and fabrication of a liquid conductivity sensor based on AgPd paste will be described. The device was designed in a four-electrode configuration on a 10 x 25 mm2 96% Al2O3 substrate. The distance between the two driving electrodes was 4 mm, whereas the distance between the two measuring electrodes was 2 mm.The device was also integrated with a Ruthenium based temperature sensor printed on the backside of the substrate. Initial characterisation showed that the conductivity sensor has a measured sensitivity and cell constant of 1.67 cm and 0.51 cm-1, respectively, when a frequency of 1 kHz square wave input was appliedto the driving electrodes. Sensor’s respond variation against temperature was measured around 27.89 μS/°C, corresponding to 2.22 temperature compensation value for salt solution. The results showed a stable response over 5 days measurement cycle, indicating the sensor’s potential for field water quality monitoring application.

Design and realisation of a turbidimeter using TSL250 photodetector and Arduino microcontroller

In this research it has been developed a turbidimeter using TSL250 photodetector and 650 nm laser light source. The method used was based on nephelometric principle with the photodetector positioned at 90o angle against the incident light from the laser source. Light intensity changes due to particles in the liquid were converted into voltage, and an Arduino microcontroller was then used to convert the measured voltage into the standart turbidity measurement unit (NTU) and displayed the results on an LCD. The system has been tested against a commercial turbidimeter, and the results showed an average accuracy of 98.7%, and good precision over 25 series of measurement and 5 day measurement cycle. The ideal measurement range of the developed system was from 10 - 150 NTU, with the smallest measurable value (resolution) of 0.17 NTU. The turbidimeter was expected to be applied in an online water quality monitoring system.

Stability optimization of TiO 2 dye-sensitized solar sub-modules in Z-type series interconnection

Dye sensitized solar cells (DSSC), one of the promising technology for renewable energy, has reached good performance in laboratory scale. In order to be implemented in practical use, it has become a necessity to enlarge the small size DSSC into large area (module) and to optimize stability of the module. In this study, dye sensitized solar sub-modules were fabricated with a size of 33 mm × 50 mm consisting of two active cells, each with a size of 10 mm × 50 mm, which are interconnected in type-z series. Working electrode of the sub-modules was prepared using a screen printing technique to deposit the TiO2 paste on glass conductive substrate with TiCl4 pre-treatment and post-treatment. The sub-modules were assembled using two types of sealant to investigate the effect of sealant on lifetime of the sub-module. I-V measurement using sun simulator with light intensity of 500 watt/m2 was applied twice in the range of six days to obtain the sub-module lifetime stability result. From the first I-V test, the highest photoconversion efficiency of the sub-module was 3.58%. In the second test results, the photoconversion efficiency was decreased significantly with the lowest percentage of efficiency degradation was 95.81%.

Sifat Optik Campuran Pasta TiO2 Partikel Nano dan Pasta TiO2 Reflektor pada Foto Elektroda Dye Solar Cell

Dalam penelitian ini, kami mengamati pengaruh dari campuran pasta TiO2 partikel nano dan pasta TiO2 reflektor yang dapat meningkatkan kinerja dye-sensitized solar cell (DSSC). Senyawa TiO2 reflektor ini berfungsi sebagai lapisan penghambur, yang diharapkan dapat meningkatkan kinerja DSSC. Dalam penelitian ini, foto elektroda DSSC dibuat dengan mencampurkan bahan pasta TiO2 partikel nano dan bahan pasta TiO2 reflektor dengan rasio dari dua bahan tersebut yang telah ditentukan. Pasta pertama adalah campuran dari bahan utama dan bahan pencampur dengan perbandingan antara pasta TiO2 partikel nano dan pasta TiO2 reflektor sebesar 95% : 5%, pasta kedua adalah campuran dengan perbandingan 90% : 10%, dan pasta ketiga dengan perbandingan 85% : 15%. Pasta hasil campuran kemudian dilapiskan pada permukaan kaca konduktif yang memiliki dimensi konduktif sebesar 1 cm x 1 cm. Sel surya DSSC hasil proses pabrikasi kemudian diukur menggunakan I-V measurement system dan Sun simulator untuk mengetahui arus, tegangan, dan efisiensi yang dihasilkan. Lapisan foto elektroda DSSC diukur dengan menggunakan UV - Visible absorbance untuk menentukan karakteristik daya serapnya terhadap cahaya yang datang pada permukaan TiO2 hasil pencampuran. Kami juga telah melakukan pengukuran menggunakan alat SEM (scanning electron microscope) untuk mengetahui karakteristik permukaan hasil pencampuran kedua jenis pasta yang telah digunakan. Hasil pengukuran menunjukkan bahwa DSSC hasil pencampuran pasta dengan perbandingan 85% pasta TiO2 partikel nano terhadap 15% pasta TiO2 reflektor memiliki ukuran partikel yang paling besar dan menghasilkan efisiensi yang paling besar pula.

Study on the synthesis of Indium Tinoxide (ITO) nanomaterial using sol gel process and its potential for CO gas detection

This paper described the synthesis of doped and undoped nanomaterial Indium Tinoxide (ITO) using sol-gel process with the base materials from Indium Nitride (In(NO3)) and Tin Chloride (SnCl4). Doping was done using Palladium Chloride (PdCl), with the molar ratio of 90:10 and 70:30, respectively. Physical characteristics of the nanocrystallites were examined using SEM, EDS, XRD, and FTIR, whereas its resistivity was tested agaist CO gas. The result showed that the ITO powders have a crystal size smaller than 100 nm, with a cubic crystal structure (byxbite type), and having strong molecular bonds for In-O-In and Sn-O-Sn. The response to CO gases showed a decreasing resistivity with increasing CO gas concentration, showing its potential for gas sensor application.