I Dewa Putu Hermida

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.

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.

Enhanced Power Factor of Single Crystalline Lead Telluride Nanowire

We present the thermoelectric properties of individual PbTe (lead telluride) nanowire (NW) grown by a stress induced method. Temperature-dependent thermoelectric power and electrical conductivity in PbTe NW with diameter 125 nm were investigated in temperature ranging of 300−400 K. The PbTe NW was found to have a Seebeck coeficient S and electrical conductivity σ of −121 μV K−1 and 138 S cm−1 at 300 K, respectively. The calculated power factor (PF) of PbTe NW (d = 125 nm) demonstrate an enhancement, wich is higher than that have been previously reported in PbTe NWs. Such an enhanced thermoelectric performance can in part be attributed to the size effect of nanowires.

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.

Simulation and realization of bandpass filter (BPF) 456 MHz using thick film technology substrate-based alumina

A research a band-pass filter module uses technology based film thick alumina substrate with the major components using SMT (surface mount technology). With a 60 MHz bandwidth, the −3 dB cutoff signal at a frequency of 486 MHz for the tape top side, as well as for the 426 MHz frequency band lower side. To produce the steepness of the above −30 dB and ripple 0.1 dB the pass-band region, the filter design using a seven pole with family order Butterworth filter used. To lower the cutoff frequency, stopband width (Fs) is designed about 20% at a frequency of 340.8 MHz, with stop-band depth (As) of about −40 dB. As for the upper cutoff frequency, stopband width (Fs) designed about 20% at a frequency of 583.2 MHz, with stopband depth (As) of about −40 dB. Using the components of surface mount technology (SMT), then generated band-pass filter module with small dimensions, compact and has a high Q. In this stage of the simulation, software used Elsie tonne of software version 2.72, the design process of printed circuit board (PCB) using Protel 99SE, while the phase measurements using a Vector Network Analyzer R3770 Advantest type with a frequency range between 300 kHz to 20 GHz. These filters have been using in radar applications ISRA (Indonesian Sea Radar) with good results.

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.