Papers by Keyword: pH Sensor

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Authors: Bo Liao, Peng Long, Hao Wen Huang, Shao Hua Shen
Abstract: The uniform Au nanoclusters ( NCs) were prepared with a simple method, and we used the uniform Au NCs and annioic tetrakis (4-sulfonatophenyl) (TPPS) porphyrin to prepare a pH sensor, of which fluorescence can be reversely modulated depending on the pH change. The fluorescence modulation of the pH sensor is related to fluorescence resonant energy transfer(FRET)from the Au NCs to TPPS.
Authors: Libu Manjakkal, Katarina Cvejin, Jan Kulawik, Krzysztof Zaraska, Dorota Szwagierczak
Abstract: Fresh water deficiency caused by climate change calls for employing novel measures to ensure safety of drinking water supply. Wireless sensor networks can be used for monitoring hydrological conditions across wide area, allowing flow forecasting and early detection of pollutants. While there are no fundamental technological obstacles to implementation of large area sensor networks, their feasibility is constrained by unit cost of sensing nodes. This paper describes a low-cost pH sensor, intended for use in fresh water monitoring. The sensor was fabricated in a standard thick film process, and an off-the-shelf resistive paste was used as a sensing material. For the fabrication of sensor, RuO2 resistive paste was screen printed on the alumina substrate with silver conducting layer. Test solutions with pH ranging from 2 to 10 were prepared from HCl or KOH solutions. The potential difference between reference and sensing electrode (electromotive force emf of an electrochemical cell) should be proportional to the pH of a solution according to the Nernst equation. The fabricated sensor exhibits Nernstian response to pH. Influence of storage conditions on sensing performance was also investigated.
Authors: Badrul Aisham Md Zain, Muhammad Farhan Khasim, Salihatun Md Salleh, Md Saidin Wahab
Abstract: Shrimp culture is the fastest growing sector of the aquaculture industry in Malaysia. In culturing tiger prawn, the pH level needed for water is around 7.0-8.5. Currently, prawn farmer in Malaysia still using a manual method to control the water pH level by adding chemical (Lime), in which, the process required constant monitoring and control by labor. Since the prawns are so sensitive on pH level, an automatic pH control system is required to maintain the water pH automatically and precisely. This research was conducted to design a system that can control and provide feedback on the changes of pH level and been implemented at the reservoir tank that can act as water storage tank and prawn pond. Control system and pH sensor are the important components in controlling the pH level. Input from pH sensor was processed by controller. Moreover, after an error is detected by controller, the correction will be delivered to the system as a feedback process. Nitric acid with concentration of 0.001M was added to 25 liter water in tank 1 so that the pH level is decreased to pH 3.00. Different concentrations were used for slaked lime; 0.5M, 0.4M. 0.3M, 0.2M and 0.1M, to increase the pH from acid to slightly alkaline in the range of pH value 7.00-8.50. Slaked lime was pumped to Tank by water pump and it will stop if the pH level reaches the setting level. The time for the system to recover from pH 3.00 to 7.00-8.50 was recorded. The results shows that slaked lime with the concentration 0.5M has the fastest recover time which was 29s follow by 0.4M in 69s, 0.3M in 92s, 0.2M in 151s and 0.1M in 252s, respectively.
Authors: Su C.S. Stephen, Mohd Khairuddin Md Arshad, Mohammad Nuzaihan Md Nor, M.F.M. Fathil, A. Rahim Ruslinda, Uda Hashim
Abstract: This paper presents the characteristics of the doped polysilicon nanowire for pH sensors. The fabrication involved two chromium mask designs. Example the first mask is used for the polysilicon nanowire pattern and the other one is for pad patterning. It involved of photolithography, deposition, etching and wet oxidation process. Different length, number of polysilicon are fabricated and then subjected to voltage, current and pH measurement. APTES is being introduced to improve the sensitivity of the polysilicon nanowire. For the low pH, the conductivity is high, while for the high pH, the conductivity is low. The impact on investigating length is insignificant to the sensitivity of the doped polysilicon nanowire.
Authors: Lien Van der Schueren, Karen de Clerck
Abstract: Recently, an increasing interest in pH-sensitive textiles is recognized. These chromic textiles can be used as flexible sensors for various applications. The aim of the current research is to develop textile pH-sensors through the application of pH-sensitive dyes on various textile materials using different techniques. The results of our study show that halochromic dyes can be incorporated into conventional textiles by a conventional dyeing technique. Also coating the fabrics with a sol-gel layer containing the halochromic dye proved to be successful. The majority of these developed materials showed a clearly visible color change with a pH-variation. The response of the sensors was dependent on the density of the fabric but was generally relatively fast, especially for the sol-gel treated fabrics. The halochromic coloration of nanofibres was realized by directly adding the dyes during the fiber formation, which was shown to be highly effective. Again, a clear halochromic shift was observed. The response of these sensors was fast thanks to the high porosity of nanofibrous non-wovens. Yet, it should be kept in mind that the halochromic behavior of the dyes in the textile matrix altered compared to their behavior in solution which is most likely attributed to dye-fiber interactions. Generally we can conclude that various coloration techniques showed to be effective for the development of innovative textile pH-sensors.
Authors: Zhan Wei Xu, Gui Lin Zheng
Abstract: A high-precision pH sensor based on electrochemical principle is proposed in the paper. The principle of the sensor, the performance parameters of MCU, hardware architecture and experiment are introduced. The NEC microprocessor, which is low-power and high stability, is adopted as core processor. The three operational amplifiers same-phase parallel amplifying circuit not only matches the impendence of the pH combination electrode, but also eliminates the impact of wire resistance on pH measurement. The system's capacity of resisting disturbance is improved. Using 18-bit AD converter, which has programmable amplifier on chip, improves measurement accuracy. Both theoretical analysis and experimental results show the effectiveness of the pH sensor. A full description of the pH sensor and implementation are presented.
Authors: Chao Jin Wang, Gui Mei Cai, Jin Yin Zhang, Shuan Xia Du
Abstract: Abstract A tungsten electrode modified with polyaniline was prepared as working electrode, the platinum wire electrode for counter electrode, and the saturated Ag/AgCl redox system for reference electrode, with the base on solution H2SO4 (1.5mol/L) vs. aniline solution 0.1mol/L. The sensor showed a Nernst response in the pH range of 2~12 and a response time less than 1 min. Connected the tungsten filament electrode and silver wire electrode (mentioned above) to the anode and cathode of the pHS-25 type pH meter respectively, inserted the electrodes to the measured positions of the sample, and then recorded the potential reading when the potential value was stable, the results would be quantified by the curve (E-pH curve) finally.The sensor has been successfully employed to determine pH in the crucian from the live fish to the putrefied fish.
Authors: Kyong Soo Lee, Jea Hong Kwon, Seung Il Moon, Woo Sung Cho, Yun Hi Lee, Byeong Kwon Ju
Abstract: In this paper, We presents experimental results that demonstrate the pH sensing capability of MW-CNTs. High-density, well-aligned carbon nanotubes, which are MW-CNTs and vertically aligned on a large area of substrate, has been synthesized. The absorption of different range of pH buffer solution in the MW-CNTs changes the conductivity of the MW-CNTs at room temperature. A MEMS-based fabrication process was developed to fabricate a device where MWCNTs based sensing material was precisely assembled pattern.
Authors: A.Y.P. Puah, Sharipah Nadzirah, Mohd Khairuddin Md Arshad, R.M. Ayub, A. Rahim Ruslinda, Uda Hashim
Abstract: Optimization gap size and integration of TiO2 nanoparticles thin film produce a sensitive sensor device. Sol-gel spin coated TiO2 nanoparticles thin film is coated on a conventional fabricated IDEs with gap sizes of 7 μm, 10 μm, 14 μm and 17 μm which is then validated through electrical characterization. I-V characteristics of without and with TiO2 thin film of various gap sizes are subjected to pH test are then plotted to describe the resistance of the devices and correlate with the sensitivity measurement. Sensing devices show that devices with larger spacing and greater pH values have higher current. On the other hand, integration of TiO2 thin film reduced the resistance of devices. Among the four gap sizes, 7 μm gap sized device is the most sensitive one due to the tremendous difference after small amount of pH dropped on surface, thus lowering the detection limit.
Authors: A.J. Martins, M. Benelmekki, V. Teixeira, P.J.G. Coutinho
Abstract: Pt nanoparticles were produced by reverse micelle templating using DTAB. The resulting nanoparticles showed sizes between 250nm and 500nm and formed clusters. Thioglycolic acid (TGA) was covalently attached to the nanoparticle surface as a stabilizer and as. The Pt nanoparticles were dispersed in water and the dependence of its absorvance on the pH of the solution was studied. The spectra showed surface plamon absorption band at 280nm and also red shifted bands that were attributed to clusters of nanoparticles. It was found that the fraction of cluster population depends on the pH of the aqueous solution and that the response of the Pt nanoparticles to pH variations has a memory effect (hysteresis). The possibility of using these Pt nanoparticles in smart labels for food packaging is outlined.
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