Abu Bakar Md. Ismail

New Contactless Inductive Sensor for the Measurement of Concentration of an Electrolytic Solution

In this paper an inductive sensor with a new and simple contactless structure to determine the concentration of an electrolytic solution is presented. The authors propose a novel idea of designing the sensing coil of the sensor so that the magnetic field is focused inside the conducting liquid, thereby increasing the sensitivity of the sensing coil. By detecting the change in inductance of the sensing coil due to a solution of known concentrations of a particular electrolyte, a database is created. With the help of this database it is possible to estimate the unknown concentration of an electrolytic solution. It was tested for various concentrations of NaCl and it shows a distinct response for each concentration.

Estimation of electrolytic concentration in aqueous solution with higher accuracy using electromagnetic multi-functional sensing

Abstract In this paper non-contact multi-functional sensing technique is investigated for the measurement of low concentration of electrolyte in aqueous solution with higher accuracy and reliability. With the experimental data of a practically designed multi-functional sensor, the improvement is statistically analyzed. Primary estimations of the concentration are obtained by mathematically modeling the sensor responses in inductive and capacitive sensing functions. The final estimation of the concentration combining the two means of the primarily estimated concentration with two optimum weights on each mean is proposed. With the experimental data of K 2 SO 4 solution a considerable improvement in the variance of the finally estimated concentration was obtained.

Porous silicon: A material of choice in solar energy harvesting

Porous silicon (PSi) has drawn considerable attention as material for solar cell and sensor applications because of its attractive properties like large surface area within a small volume, controllable pore sizes, convenient surface chemistry, and the ability to modulate refractive index as a function of depth. This talk will focus on the fabrication and characterization of PSi and its possible application in solar energy harvesting. A novel structure for hybrid solar cell containing P3HT:PCBM as photoactive material with porous silicon as the anode will be analyzed. The pore dimension was found to play a crucial role on the performance of the hybrid solar cell. When the pore diameter was tuned to a length comparable to the carrier diffusion length of P3HT:PCBM system the photocurrent enjoyed a huge enhancement. In another application, PSi in a heterostructure of Al/c-Si/PSi/α-Fe2O3 as a photoanode in solar water splitting will also be reported. This photoanode increased the photocurrent at all potentials higher than that of bare Fe2O3, and a significant cathodic potential shift was observed, demonstrating that Al/c-Si/PSi/α-Fe2O3 photoanode could be used as an efficient photocatalyst in solar water splitting with a lower external bias. Altogether it appears that PSi could be a promising material in solar energy harvesting.

Fabrication of uniform-macroporous silicon and its possible application in hybrid solar cell

This report presents the fabrication of uniform-macroporus-silicon (macro-PSi) using a chemical route. Electrochemical etching of the silicon wafer with Dimethyl sulfoxide (DMSO) was utilized to fabricate macro-PSi. Almost uniform pore formation was observed by Scanning Electron Microscope (SEM). The pore-size distribution calculated from the SEM image clearly shows the nearly uniform nature of the fabricated macro-PSi. The uniform-porosity can be tuned well via adjusting the etching current and time. The fabricated macro-PSi with Aluminium (Al) as the back-contact was applied as a cathode of bulk-heterojunction organic solar cell to exploit the high-specific area of the macro-PSi for efficient charge collection. An enhancement in short-circuit current indicates an enhancement in the charge collection efficiency using macro-PSi as cathode.

Investigation on the influence of LaCl3 concentration on the electrical conduction mechanism of chemical-bath deposited LaF3/porous-silicon structure

Abstract Effect of LaCl3 concentration on the electrical conduction mechanism of LaF3/porous silicon (PS) structure has been investigated in this work. LaF3 layers have been deposited by a novel chemical bath deposition (CBD) technique. With this simple technique, LaF3 produced as LaCl3 are made to react with hydrofluoric (HF) acid on the porous silicon substrate. This enables direct deposition of LaF3 on the pore walls of the porous silicon leading to a successful passivation of PS. The compositions of the deposited LaF3 were confirmed by Energy Dispersive of X-ray (EDX) analysis. The electrical conduction study has been done by impedance analyzer (HP4294A). From this study it can be concluded that the conductance increases with LaCl3 concentration but decreases for higher concentration.

Dependency of built-in potential of LaF3/porous-silicon heterostructure prepared by chemical bath deposition technique on the concentration of LaCl3 and annealing temperature

Effect of LaCl3 concentration and annealing temperature on the built-in potential of LaF3/PS heterojunction has been investigated in this report. LaF3 layers have been deposited by a novel chemical bath deposition (CBD) technique. With this simple technique LaF3 produced as LaCl3 are made to react with hydrofluoric acid on the porous silicon (PS) substrate. This enables direct deposition of LaF3 on the pore walls of the PS leading to a successful passivation of PS. The compositions of the deposited LaF3 were confirmed by energy dispersive of X-ray analysis. The built-in potential decreases with LaCl3 concentration and increases with annealing temperature. Therefore, by changing the LaCl3 concentration and annealing temperature quality of the LaF3 layer on PS can be optimized. From the experimental results it can be concluded that lanthanum fluorides can be deposited on the PS surface by the CBD technique, which provides the required passivation for PS. This passivation can enable the PS to be considered as an important material for photonics.

Use of silicon nanoparticle for the photocurrent enhancement of organic solar cell

This report presents the enhancement of photocurrent of bulk heterojunction organic solar cell (OSC) using silicon nanoparticles (Si-NPs). Si-NPs were mixed homogeneously with the blend of poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) polymer by sonication. The solar cell was fabricated by sandwiching Si-NPs mixed bulk-heterojunction of P3HT:PCBM blend between Indium-tin-oxide (ITO) and Aluminium (Al) contacts. Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Analysis (EDAX) of the Si-NPs mixed blend confirmed the presence of the Si-NPs. Si-NPs were found to enhance the absorption of the P3HT:PCBM. The absorption was higher when the blend was spin-coated at lower speed. Absorption was also found to increase with the thickness of the coated layer. As a consequence of addition of the Si-NPs with the P3HT:PCBM huge enhancement of solar-cell photocurrent was observed. Experimental results show that the performance of OSC can be enhanced using Si-NPs mixed with P3HT:PCBM.