The fabrication of a ZnO/Au nanosquare-array electrode was successfully carried out for the detec... more The fabrication of a ZnO/Au nanosquare-array electrode was successfully carried out for the detection of glucose concentration in biomedical applications. The fabrication of the ZnO/Au nanosquare array using an ultra-thin alumina mask (UTAM) based on the imprinted anodic aluminum oxide (AAO) template and the direct current (DC) sputtering method was able to produce a very well-ordered nanosquare arrangement with a side size of 300 nm and a thickness of 100 nm. Tests were done to evaluate the performance of the electrode by means of cyclic voltammetry (CV) which showed that the addition of glucose oxidase (GOx) increased the sensitivity of the electrode up to 1180 ± 116 μA mM−1cm−2, compared with its sensitivity prior to the addition of GOx of 188.34 ± 18.70 mA mM−1 cm−2. A iox/ired ratio equal to ~1 between the peaks of redox reactions was obtained for high (hyperglycemia), normal, and low (hypoglycemia) levels of glucose. The ZnO/Au nanosquare-array electrode was 7.54% more sensiti...
3D printing technology was capable of fabricating phantoms to enhance quality assurance in radiat... more 3D printing technology was capable of fabricating phantoms to enhance quality assurance in radiation therapy. The ideal phantom has properties equivalent to the real tissue. However, 3D Printing has the limits to mimicking the attenuation properties of various tissues because during 3D printing there can be only one type of material. The purpose of this study was to evaluate the effect of infill percentage and infill patterns of 3D printing technology to simulate various types of tissue. This study used 25 samples measuring 5 × 5 × 1 cm3 from PETG material. The 20 samples were printed using variations infill percentages from 5 - 100% and the infill pattern in lines. The five samples were then printed with the infill percentage constant at 50% and used the infill pattern triangles, grid, gyroid, octet, and concentric. We used Computed Tomography (CT) to determine the Hounsfield Unit (HU) value for each sample and evaluated the suitability of each sample for phantom applications in ra...
Blood cancer causes a significant increase in the concentration of Leukocytes, which can be broke... more Blood cancer causes a significant increase in the concentration of Leukocytes, which can be broken down through dielectrophoresis and electrochemical procedures. Therefore, the electric field plays an important role in the migration of leukocytes to high voltage areas. This is because different electrode arrangements produce varying electric field distributions. Furthermore, this study applied finite element methods to generate electric fields when electrodes with an AC voltage were applied to blood placed in a chamber. Therefore, in this study, variations of mediums and electrode arrangements were investigated, which led to the recommendation of 3 models. The objective was to investigate electrode arrangements that produce optimal electric field distribution for the three models to exhibit a booster of electric field distribution. The maximum electric field is generated close to the electrode (Z=2 mm and Z=92 mm) for any material (i.e. normal blood, B lymphocyte, and T lymphocyte) ...
The fabrication of the photoanode of the n-type CuWO4 nanorod arrays was successfully carried out... more The fabrication of the photoanode of the n-type CuWO4 nanorod arrays was successfully carried out through electrochemical deposition using anodic aluminum oxide (AAO) control templates and for the first time produced distinct gaps between the nanorod arrays. The effectiveness and efficiency of the resulting deposition was shown by the performance of the photoelectrochemical (PEC) procedure with a current density of 1.02 mA cm−2 with irradiation using standard AM 1.5G solar simulator and electron changed radiation of 0.72% with a bias potential of 0.71 V (vs. Ag/AgCl). The gap between each nanorod indicated an optimization of the electrolyte penetration on the interface, which resulted in the expansion of the current density as much as 0.5 × 1024 cm−3 with a flat band potential of 0.14 V vs. Ag/AgCl and also a peak quantum efficiency of wavelength 410 nm. Thus, also indicating the gaps between the nanorod arrays is a promising structure to optimize the performance of the PEC water sp...
INTERNATIONAL CONFERENCE ON SCIENCE AND APPLIED SCIENCE (ICSAS2020), 2020
Orientation and characterization of immobilized antibodies for improved immunoassays (Review) Bio... more Orientation and characterization of immobilized antibodies for improved immunoassays (Review) Biointerphases 12, 02D301 (2017);
The delivery of radiation therapy to patients requires prior planning made by medical physicists ... more The delivery of radiation therapy to patients requires prior planning made by medical physicists to achieve radiotherapy goals. Radiotherapy has a plan to eradicate the growth of cancer cells by giving high doses and minimizing the radiation dose to normal tissue. Evaluation of planning is generally done based on dosimetric parameters, such as minimum dose, maximum dose, and means dose obtained from the DVHs data. Based on the same DVHs, data were evaluate dinterms of biological effects to determine the highest possible toxicity in normal tissue after the tumor had been treated with radiation using the NTCP model. The evaluation was conducted by selecting three DICOM-RT data of post-mastectomy right breast cancer patients who had been prescribed a dose of 50 Gy obtained from the Hospital MRCCC Siloam Semanggi database. All data were processed using open-source software DICOManTX to get the DVH and isodose information. Matlab-based CERR software was used to calculate the NTCP model. ...
The image reconstruction for two-dimensional high-speed Electrical Impedance Tomography (EIT) ha... more The image reconstruction for two-dimensional high-speed Electrical Impedance Tomography (EIT) has been successfully studied with multi-frequency current injection. The aim of this study is to get the best image reconstruction under the influence of multi-frequency current injection of this EIT system. In this method, we used current injection at 1 mA with varies of frequency in the range 10 to 50 kHz injected at the practical phantoms with 16 electrodes. Polyvinyl chloride (PVC) cylinder was put in the practical phantom as the anomaly. Then, The boundary voltage of the practical phantom was measured by the voltage measurement circuit. After that, it processed in the computer with Gauss-Newton Algorithm to got image reconstruction. The result showed that the best image reconstruction was achieved at 10 kHz of frequency current injection. The best image reconstruction had more accuracy of shape, position and electrical properties of an anomaly in boundary phantom than another image reconstruction result.
The applications of Self-Mixing Interferometry (SMI) have been popular in many fields, including ... more The applications of Self-Mixing Interferometry (SMI) have been popular in many fields, including biomedical signals. The self-mixing effect occurs from the coherent backcoupling of the reflected or scattered lights from a target surface. The reflected lights will be detected by a photodiode which has been integrated in one device with the laser. That's why the SMI sensor is quite practical, affordable and simple. However, SMI has the serious problem with the presence of speckle effect in measured signal. The speckle effect produced by the human tissue is called "biospeckles." The biospeckles observed from the skin tissues contain information about the blood flow in dermal capillarities, heartbeat, and others. These biospeckle patterns cause random modulations that will be detected as random amplitude and spectrum by photodiode. In this paper we present a technique to characterize speckle effect on measurement of blood flow in fingertip using sensor based on Self-Mixing Interferometry (SMI). We used a laser diode 785 nm as a light source and a constant current of 70 mA as a current source which is irradiated on the skin tissue in the fingertip. Then, the backscattered light reenters the laser cavity and it will be detected by photodiode. The SMI signal with speckle effect will be processed by Continuous Wavelet Transform for reconstruction and detection fringe. Signal processing results show that the number of detected speckle fringes depends largely on determining the number of wavelet waves and the scale used. The fringe pattern resulting from the reconstruction of the signal can be used to determine the frequency of speckles due to object movement. The average speckle frequency of fingertip is 0,5-0,7 Hz.
This study aims to evaluate the capability of Ageratum conyzoides and Mikania micrantha extracts ... more This study aims to evaluate the capability of Ageratum conyzoides and Mikania micrantha extracts to synthesize silver nanoparticles (AgNPs) and their antibacterial capability against gram-positive and gram-negative bacteria. Several properties of the synthesized AgNPs, including plasmonic, biomolecule bonding, shape, size, and antibacterial, were investigated. Ultraviolet-visible (UV-vis) spectroscopy was employed for characterizing their plasmonic properties. Functional groups on the produced AgNPs were investigated by Fourier-transform infrared (FT-IR) spectroscopy. The size and shape of the AgNPs were identified using the field-emission scanning electron microscopy (FESEM). Inhibition zone measurement was carried out for evaluating the antibacterial capability. This study showed that the extracts of A. conyzoides and M. micrantha were able reducing agents as evidenced by the formation of the spherical AgNPs. UV-vis spectroscopy, FT-IR spectroscopy, and FESEM confirmed the physicochemical characteristics of AgNPs. AgNPs that were synthesized using M. micrantha were slightly smaller than those produced using A. conyzoides. In general, the present work establishes that the synthesized AgNPs have antibacterial capability depending on their size and synthesis procedure.
To increase energy conversion efficiency of dye-sensitized solar cells (DSSCs), carbon nanotubes ... more To increase energy conversion efficiency of dye-sensitized solar cells (DSSCs), carbon nanotubes (CNTs) were added to TiO2 gel-like solution. Modified acid-catalyzed sol-gel method was used with the doctor blade coating technique to obtain thin films of CNT/TiO2 nanocomposite photoanode. CNT/TiO2 paste was applied onto the conductive glass to generate a 0.25 cm2 active area which was later annealed at 350°C, 450°C, and 550°C for 60 min. Characterization of the CNT/TiO2 paste was performed using x-ray diffraction. Results showed that the crystalline phase of the particles was anatase. The micrograph obtained using field emission scanning electron microscopy demonstrated that the pastes are highly porous. Brunauer-Emmett-Teller analysis was performed to determine the CNT/TiO2 surface area and particle size. The DSSC with the CNT/TiO2 photoanodes annealed at 550°C showed the highest incident photon-to-charge carrier efficiency value of 0.95% compared with the DSSCs with photoanodes annealed at 350°C and 450°C (0.70% and 0.83%, respectively). The observed efficiencies of the DSSCs with CNT/TiO2 photoanode annealed at the three different temperatures were 2.62%, 2.65%, and 3.13%. The electrochemical impedance spectroscopy analysis showed that the DSSCs with photoanodes developed using the highest annealing temperature (550°C) have higher electron lifetime of 70.423 ms and lower effective recombination rate of 1.42 × 10−2 s−1, thereby improving the performance of CNT/TiO2 DSSCs.
Based on the experimental results of PMMA planar waveguide fabrication and a planning to employ P... more Based on the experimental results of PMMA planar waveguide fabrication and a planning to employ PMMA as the waveguide in a directional coupler structure, a study of switching characteristic in the directional couplers is presented. To obtain a low crosstalk as the switching characteristic, asymmetry factor of the waveguides width of the directional couplers is investigated. The calculation of the propagation constants and the crosstalk are carried out by using a finite difference mode solver and a finite difference beam propagation method, respectively. A fabrication tolerance of the designed structure with the low cross-talk is shown to perform switching operation.
Blood carrying more leukocytes can induce differences in electrical and magnetic properties. This... more Blood carrying more leukocytes can induce differences in electrical and magnetic properties. This work describes the effect of leukocyte concentration on the distribution of electric fields. The finite difference time domain approach of electric field distribution using normal blood and leukocyte has been analyzed. The electric field in the blood and leukocytes have the same peak at a wavelength of 400nm. Ag nanosquare with dimensions of 350×350nm2 in blood and leukocyte medium has a different maximum electric field of 7.35 × 10−7V/m with a peak wavelength difference of 0.22nm. The results of this work are beneficial to expected and provide an interpretation of blood cancer detection using an Ag nanosquare arrays sensor.
The design and optimization process of ball mill to reduce particle size of calcium carbonate mat... more The design and optimization process of ball mill to reduce particle size of calcium carbonate materials
The development of silver (Ag) thin films and the fabrication of Ag nanosquare arrays with the us... more The development of silver (Ag) thin films and the fabrication of Ag nanosquare arrays with the use of an anodic aluminum oxide (AAO) template and leaf extracts were successfully carried out using the DC sputtering and spin coating deposition methods. Ag thin films and Ag nanosquare arrays are developed to monitor cancer prognosis due to the correlation between serum albumin levels and prognostic factors, as well as the binding of serum albumin to the surface of these electrodes. Nanosquare structures were fabricated using AAO templates with varying diameters and a gap distance between adjacent unit cells of 100 nm. The nanosquare array with a diameter of 250 nm and irradiated with electromagnetic waves with a wavelength of around 800 nm possessed the greatest electric field distribution compared to the other variations of diameters and wavelengths. The results of the absorption measurement and simulation showed a greater shift in absorption peak wavelength when carried out using the...
Traditional thin films and nanostructure are the most reasonable candidates to build the next gen... more Traditional thin films and nanostructure are the most reasonable candidates to build the next generation of photoelectrochemical water splitting system with outstanding optical and electrical properties. Especially the use of nanostructure arrays as photoelectrodes might complement the traditional semiconductor photoelectrodes in providing close transfer distance of photoinduced carriers and the increase in the surface reaction sites than thin films. Both of the reasons reduce the probability of carriers recombination and thus enhancing the photoelectrochemical performances. In this work, we demonstrated highly efficient water splitting performance of CuBi2O4 nanopillars compared to thin film CuBi2O4 photocathode. The CuBi2O4 nanopillars were fabricated by electrodeposition on anodized aluminum oxide (AAO) template. The CuBi2O4 nanopillars photocathode gave a notable improvement in photocurrent, from −0.50 to −1.50 mA cm−2 at −0.45 V vs. Ag/AgCl by the external quantum yield more th...
Abstrak-Telah dikembangkan sensor konsentrasi glukosa dengan prinsip macrobending dari serat opti... more Abstrak-Telah dikembangkan sensor konsentrasi glukosa dengan prinsip macrobending dari serat optik multimode stepindex dengan variasi panjang kupasan 2 cm, 3 cm, dan 4 cm. S etiap panjang kupasan dilengkungkan dengan diameter kelengkungan 2 cm, 3 cm, dan 4 cm. Larutan glukosa yang diuji memiliki konsentrasi 0% (aquades), 5%, 10%, 15% dan 25%. S umber cahaya yang digunakan LED dengan panjang gelombang 660 nm dan detektor yang digunakan yaitu BF5R-D1-N yang telah dikalibrasi dengan menggunakan Optical Power Meter. Dari hasil pengukuran diperoleh bahwa semakin besar diameter kelengkungan serat optik semakin besar pula daya keluaran, dan semakin panjang daerah kupasan semakin kecil daya keluaran.
Abstrak-Penelitian sensor regangan dengan variasi pencacatan pada serat optik multimode step inde... more Abstrak-Penelitian sensor regangan dengan variasi pencacatan pada serat optik multimode step index tipe FD-620-10 yang memiliki diameter serat 1 mm telah dilakukan. Cladding serat optik diberikan pencacatan dengan variasi pencacatan sebanyak 1 sampai 5 buah dengan lebar pencacatan 3 mm dan jarak antar pencacatan dibuat dengan ukuran yang sama yaitu sebesar 1 cm. Untuk mengetahui besaran daya keluaran akibat regangan digunakan LED (Light Emitting Diode) panjang gelombang 660 nm sebagai sumber cahaya, microdisplacement, dan BF5R-D1-N sebagai detektor cahaya. Pengukuran sensor regangan berbasis serat optik menunjukkan bahwa sensitivitas dengan pencacatan lebih bagus dari fiber optik normal.
Dye Sensitized Solar Cell (DSSC) merupakan generasi ketiga dari sel surya. Sel surya jenis ini te... more Dye Sensitized Solar Cell (DSSC) merupakan generasi ketiga dari sel surya. Sel surya jenis ini tersensitisasi zat pewarna. DSSC dibentuk dengan struktur sandwich dimana terdapat lima bagian antara lain : kaca ITO (Indium Tin Oxide) sebagai substrat; TiO2 sebagai bahan semikonduktor; dye (kunyit-manggis-daun alfalfa) sebagai donor elektron; elektrolit gel sebagai transfer elektron dan active carbon sebagai katalis pada elektroda pembanding. Serbuk TiO2 berukuran nanometer didapatkan melalui sintesis dengan metode kopresipitasi. Dari penelitian yang telah dilakukan, efisiensi DSSC dengan ketebalan lapisan TiO2 berukuran 10 µm lebih besar jika dibandingkan dengan ketebalan lapisan 20 µm dan 30 µm. Hasil efisiensi DSSC tersebut yaitu 0.25% untuk ketebalan lapisan TiO2 berukuran 10 µm , 0,143% ketebalan lapisan TiO2 berukuran 20 µm, dan 0.195% untuk ketebalan lapisan TiO2 berukuran 30 µm.
Nanowire (NW) structures is an alternative candidate for constructing the next generation photoel... more Nanowire (NW) structures is an alternative candidate for constructing the next generation photoelectrochemical water splitting system, due to the outstanding optical and electrical properties. NW photoelectrodes comparing to traditional semiconductor photoelectrodes shows the comparatively shorter transfer distance of photo-induced carriers and the increase amount of the surface reaction sites, which is beneficial for lowering the recombination probability of charge carriers and improving their photoelectrochemical (PEC) performances. Here, we demonstrate for the first time that super-long Cu2O NWs, more than 4.5 μm, with highly efficient water splitting performance, were synthesized using a cost-effective anodic alumina oxide (AAO) template method. In comparison with the photocathode with planar Cu2O films, the photocathode with Cu2O NWs demonstrates a significant enhancement in photocurrent, from –1.00 to –2.75 mA/cm2 at –0.8 V versus Ag/AgCl. After optimization of the photoelectr...
The fabrication of a ZnO/Au nanosquare-array electrode was successfully carried out for the detec... more The fabrication of a ZnO/Au nanosquare-array electrode was successfully carried out for the detection of glucose concentration in biomedical applications. The fabrication of the ZnO/Au nanosquare array using an ultra-thin alumina mask (UTAM) based on the imprinted anodic aluminum oxide (AAO) template and the direct current (DC) sputtering method was able to produce a very well-ordered nanosquare arrangement with a side size of 300 nm and a thickness of 100 nm. Tests were done to evaluate the performance of the electrode by means of cyclic voltammetry (CV) which showed that the addition of glucose oxidase (GOx) increased the sensitivity of the electrode up to 1180 ± 116 μA mM−1cm−2, compared with its sensitivity prior to the addition of GOx of 188.34 ± 18.70 mA mM−1 cm−2. A iox/ired ratio equal to ~1 between the peaks of redox reactions was obtained for high (hyperglycemia), normal, and low (hypoglycemia) levels of glucose. The ZnO/Au nanosquare-array electrode was 7.54% more sensiti...
3D printing technology was capable of fabricating phantoms to enhance quality assurance in radiat... more 3D printing technology was capable of fabricating phantoms to enhance quality assurance in radiation therapy. The ideal phantom has properties equivalent to the real tissue. However, 3D Printing has the limits to mimicking the attenuation properties of various tissues because during 3D printing there can be only one type of material. The purpose of this study was to evaluate the effect of infill percentage and infill patterns of 3D printing technology to simulate various types of tissue. This study used 25 samples measuring 5 × 5 × 1 cm3 from PETG material. The 20 samples were printed using variations infill percentages from 5 - 100% and the infill pattern in lines. The five samples were then printed with the infill percentage constant at 50% and used the infill pattern triangles, grid, gyroid, octet, and concentric. We used Computed Tomography (CT) to determine the Hounsfield Unit (HU) value for each sample and evaluated the suitability of each sample for phantom applications in ra...
Blood cancer causes a significant increase in the concentration of Leukocytes, which can be broke... more Blood cancer causes a significant increase in the concentration of Leukocytes, which can be broken down through dielectrophoresis and electrochemical procedures. Therefore, the electric field plays an important role in the migration of leukocytes to high voltage areas. This is because different electrode arrangements produce varying electric field distributions. Furthermore, this study applied finite element methods to generate electric fields when electrodes with an AC voltage were applied to blood placed in a chamber. Therefore, in this study, variations of mediums and electrode arrangements were investigated, which led to the recommendation of 3 models. The objective was to investigate electrode arrangements that produce optimal electric field distribution for the three models to exhibit a booster of electric field distribution. The maximum electric field is generated close to the electrode (Z=2 mm and Z=92 mm) for any material (i.e. normal blood, B lymphocyte, and T lymphocyte) ...
The fabrication of the photoanode of the n-type CuWO4 nanorod arrays was successfully carried out... more The fabrication of the photoanode of the n-type CuWO4 nanorod arrays was successfully carried out through electrochemical deposition using anodic aluminum oxide (AAO) control templates and for the first time produced distinct gaps between the nanorod arrays. The effectiveness and efficiency of the resulting deposition was shown by the performance of the photoelectrochemical (PEC) procedure with a current density of 1.02 mA cm−2 with irradiation using standard AM 1.5G solar simulator and electron changed radiation of 0.72% with a bias potential of 0.71 V (vs. Ag/AgCl). The gap between each nanorod indicated an optimization of the electrolyte penetration on the interface, which resulted in the expansion of the current density as much as 0.5 × 1024 cm−3 with a flat band potential of 0.14 V vs. Ag/AgCl and also a peak quantum efficiency of wavelength 410 nm. Thus, also indicating the gaps between the nanorod arrays is a promising structure to optimize the performance of the PEC water sp...
INTERNATIONAL CONFERENCE ON SCIENCE AND APPLIED SCIENCE (ICSAS2020), 2020
Orientation and characterization of immobilized antibodies for improved immunoassays (Review) Bio... more Orientation and characterization of immobilized antibodies for improved immunoassays (Review) Biointerphases 12, 02D301 (2017);
The delivery of radiation therapy to patients requires prior planning made by medical physicists ... more The delivery of radiation therapy to patients requires prior planning made by medical physicists to achieve radiotherapy goals. Radiotherapy has a plan to eradicate the growth of cancer cells by giving high doses and minimizing the radiation dose to normal tissue. Evaluation of planning is generally done based on dosimetric parameters, such as minimum dose, maximum dose, and means dose obtained from the DVHs data. Based on the same DVHs, data were evaluate dinterms of biological effects to determine the highest possible toxicity in normal tissue after the tumor had been treated with radiation using the NTCP model. The evaluation was conducted by selecting three DICOM-RT data of post-mastectomy right breast cancer patients who had been prescribed a dose of 50 Gy obtained from the Hospital MRCCC Siloam Semanggi database. All data were processed using open-source software DICOManTX to get the DVH and isodose information. Matlab-based CERR software was used to calculate the NTCP model. ...
The image reconstruction for two-dimensional high-speed Electrical Impedance Tomography (EIT) ha... more The image reconstruction for two-dimensional high-speed Electrical Impedance Tomography (EIT) has been successfully studied with multi-frequency current injection. The aim of this study is to get the best image reconstruction under the influence of multi-frequency current injection of this EIT system. In this method, we used current injection at 1 mA with varies of frequency in the range 10 to 50 kHz injected at the practical phantoms with 16 electrodes. Polyvinyl chloride (PVC) cylinder was put in the practical phantom as the anomaly. Then, The boundary voltage of the practical phantom was measured by the voltage measurement circuit. After that, it processed in the computer with Gauss-Newton Algorithm to got image reconstruction. The result showed that the best image reconstruction was achieved at 10 kHz of frequency current injection. The best image reconstruction had more accuracy of shape, position and electrical properties of an anomaly in boundary phantom than another image reconstruction result.
The applications of Self-Mixing Interferometry (SMI) have been popular in many fields, including ... more The applications of Self-Mixing Interferometry (SMI) have been popular in many fields, including biomedical signals. The self-mixing effect occurs from the coherent backcoupling of the reflected or scattered lights from a target surface. The reflected lights will be detected by a photodiode which has been integrated in one device with the laser. That's why the SMI sensor is quite practical, affordable and simple. However, SMI has the serious problem with the presence of speckle effect in measured signal. The speckle effect produced by the human tissue is called "biospeckles." The biospeckles observed from the skin tissues contain information about the blood flow in dermal capillarities, heartbeat, and others. These biospeckle patterns cause random modulations that will be detected as random amplitude and spectrum by photodiode. In this paper we present a technique to characterize speckle effect on measurement of blood flow in fingertip using sensor based on Self-Mixing Interferometry (SMI). We used a laser diode 785 nm as a light source and a constant current of 70 mA as a current source which is irradiated on the skin tissue in the fingertip. Then, the backscattered light reenters the laser cavity and it will be detected by photodiode. The SMI signal with speckle effect will be processed by Continuous Wavelet Transform for reconstruction and detection fringe. Signal processing results show that the number of detected speckle fringes depends largely on determining the number of wavelet waves and the scale used. The fringe pattern resulting from the reconstruction of the signal can be used to determine the frequency of speckles due to object movement. The average speckle frequency of fingertip is 0,5-0,7 Hz.
This study aims to evaluate the capability of Ageratum conyzoides and Mikania micrantha extracts ... more This study aims to evaluate the capability of Ageratum conyzoides and Mikania micrantha extracts to synthesize silver nanoparticles (AgNPs) and their antibacterial capability against gram-positive and gram-negative bacteria. Several properties of the synthesized AgNPs, including plasmonic, biomolecule bonding, shape, size, and antibacterial, were investigated. Ultraviolet-visible (UV-vis) spectroscopy was employed for characterizing their plasmonic properties. Functional groups on the produced AgNPs were investigated by Fourier-transform infrared (FT-IR) spectroscopy. The size and shape of the AgNPs were identified using the field-emission scanning electron microscopy (FESEM). Inhibition zone measurement was carried out for evaluating the antibacterial capability. This study showed that the extracts of A. conyzoides and M. micrantha were able reducing agents as evidenced by the formation of the spherical AgNPs. UV-vis spectroscopy, FT-IR spectroscopy, and FESEM confirmed the physicochemical characteristics of AgNPs. AgNPs that were synthesized using M. micrantha were slightly smaller than those produced using A. conyzoides. In general, the present work establishes that the synthesized AgNPs have antibacterial capability depending on their size and synthesis procedure.
To increase energy conversion efficiency of dye-sensitized solar cells (DSSCs), carbon nanotubes ... more To increase energy conversion efficiency of dye-sensitized solar cells (DSSCs), carbon nanotubes (CNTs) were added to TiO2 gel-like solution. Modified acid-catalyzed sol-gel method was used with the doctor blade coating technique to obtain thin films of CNT/TiO2 nanocomposite photoanode. CNT/TiO2 paste was applied onto the conductive glass to generate a 0.25 cm2 active area which was later annealed at 350°C, 450°C, and 550°C for 60 min. Characterization of the CNT/TiO2 paste was performed using x-ray diffraction. Results showed that the crystalline phase of the particles was anatase. The micrograph obtained using field emission scanning electron microscopy demonstrated that the pastes are highly porous. Brunauer-Emmett-Teller analysis was performed to determine the CNT/TiO2 surface area and particle size. The DSSC with the CNT/TiO2 photoanodes annealed at 550°C showed the highest incident photon-to-charge carrier efficiency value of 0.95% compared with the DSSCs with photoanodes annealed at 350°C and 450°C (0.70% and 0.83%, respectively). The observed efficiencies of the DSSCs with CNT/TiO2 photoanode annealed at the three different temperatures were 2.62%, 2.65%, and 3.13%. The electrochemical impedance spectroscopy analysis showed that the DSSCs with photoanodes developed using the highest annealing temperature (550°C) have higher electron lifetime of 70.423 ms and lower effective recombination rate of 1.42 × 10−2 s−1, thereby improving the performance of CNT/TiO2 DSSCs.
Based on the experimental results of PMMA planar waveguide fabrication and a planning to employ P... more Based on the experimental results of PMMA planar waveguide fabrication and a planning to employ PMMA as the waveguide in a directional coupler structure, a study of switching characteristic in the directional couplers is presented. To obtain a low crosstalk as the switching characteristic, asymmetry factor of the waveguides width of the directional couplers is investigated. The calculation of the propagation constants and the crosstalk are carried out by using a finite difference mode solver and a finite difference beam propagation method, respectively. A fabrication tolerance of the designed structure with the low cross-talk is shown to perform switching operation.
Blood carrying more leukocytes can induce differences in electrical and magnetic properties. This... more Blood carrying more leukocytes can induce differences in electrical and magnetic properties. This work describes the effect of leukocyte concentration on the distribution of electric fields. The finite difference time domain approach of electric field distribution using normal blood and leukocyte has been analyzed. The electric field in the blood and leukocytes have the same peak at a wavelength of 400nm. Ag nanosquare with dimensions of 350×350nm2 in blood and leukocyte medium has a different maximum electric field of 7.35 × 10−7V/m with a peak wavelength difference of 0.22nm. The results of this work are beneficial to expected and provide an interpretation of blood cancer detection using an Ag nanosquare arrays sensor.
The design and optimization process of ball mill to reduce particle size of calcium carbonate mat... more The design and optimization process of ball mill to reduce particle size of calcium carbonate materials
The development of silver (Ag) thin films and the fabrication of Ag nanosquare arrays with the us... more The development of silver (Ag) thin films and the fabrication of Ag nanosquare arrays with the use of an anodic aluminum oxide (AAO) template and leaf extracts were successfully carried out using the DC sputtering and spin coating deposition methods. Ag thin films and Ag nanosquare arrays are developed to monitor cancer prognosis due to the correlation between serum albumin levels and prognostic factors, as well as the binding of serum albumin to the surface of these electrodes. Nanosquare structures were fabricated using AAO templates with varying diameters and a gap distance between adjacent unit cells of 100 nm. The nanosquare array with a diameter of 250 nm and irradiated with electromagnetic waves with a wavelength of around 800 nm possessed the greatest electric field distribution compared to the other variations of diameters and wavelengths. The results of the absorption measurement and simulation showed a greater shift in absorption peak wavelength when carried out using the...
Traditional thin films and nanostructure are the most reasonable candidates to build the next gen... more Traditional thin films and nanostructure are the most reasonable candidates to build the next generation of photoelectrochemical water splitting system with outstanding optical and electrical properties. Especially the use of nanostructure arrays as photoelectrodes might complement the traditional semiconductor photoelectrodes in providing close transfer distance of photoinduced carriers and the increase in the surface reaction sites than thin films. Both of the reasons reduce the probability of carriers recombination and thus enhancing the photoelectrochemical performances. In this work, we demonstrated highly efficient water splitting performance of CuBi2O4 nanopillars compared to thin film CuBi2O4 photocathode. The CuBi2O4 nanopillars were fabricated by electrodeposition on anodized aluminum oxide (AAO) template. The CuBi2O4 nanopillars photocathode gave a notable improvement in photocurrent, from −0.50 to −1.50 mA cm−2 at −0.45 V vs. Ag/AgCl by the external quantum yield more th...
Abstrak-Telah dikembangkan sensor konsentrasi glukosa dengan prinsip macrobending dari serat opti... more Abstrak-Telah dikembangkan sensor konsentrasi glukosa dengan prinsip macrobending dari serat optik multimode stepindex dengan variasi panjang kupasan 2 cm, 3 cm, dan 4 cm. S etiap panjang kupasan dilengkungkan dengan diameter kelengkungan 2 cm, 3 cm, dan 4 cm. Larutan glukosa yang diuji memiliki konsentrasi 0% (aquades), 5%, 10%, 15% dan 25%. S umber cahaya yang digunakan LED dengan panjang gelombang 660 nm dan detektor yang digunakan yaitu BF5R-D1-N yang telah dikalibrasi dengan menggunakan Optical Power Meter. Dari hasil pengukuran diperoleh bahwa semakin besar diameter kelengkungan serat optik semakin besar pula daya keluaran, dan semakin panjang daerah kupasan semakin kecil daya keluaran.
Abstrak-Penelitian sensor regangan dengan variasi pencacatan pada serat optik multimode step inde... more Abstrak-Penelitian sensor regangan dengan variasi pencacatan pada serat optik multimode step index tipe FD-620-10 yang memiliki diameter serat 1 mm telah dilakukan. Cladding serat optik diberikan pencacatan dengan variasi pencacatan sebanyak 1 sampai 5 buah dengan lebar pencacatan 3 mm dan jarak antar pencacatan dibuat dengan ukuran yang sama yaitu sebesar 1 cm. Untuk mengetahui besaran daya keluaran akibat regangan digunakan LED (Light Emitting Diode) panjang gelombang 660 nm sebagai sumber cahaya, microdisplacement, dan BF5R-D1-N sebagai detektor cahaya. Pengukuran sensor regangan berbasis serat optik menunjukkan bahwa sensitivitas dengan pencacatan lebih bagus dari fiber optik normal.
Dye Sensitized Solar Cell (DSSC) merupakan generasi ketiga dari sel surya. Sel surya jenis ini te... more Dye Sensitized Solar Cell (DSSC) merupakan generasi ketiga dari sel surya. Sel surya jenis ini tersensitisasi zat pewarna. DSSC dibentuk dengan struktur sandwich dimana terdapat lima bagian antara lain : kaca ITO (Indium Tin Oxide) sebagai substrat; TiO2 sebagai bahan semikonduktor; dye (kunyit-manggis-daun alfalfa) sebagai donor elektron; elektrolit gel sebagai transfer elektron dan active carbon sebagai katalis pada elektroda pembanding. Serbuk TiO2 berukuran nanometer didapatkan melalui sintesis dengan metode kopresipitasi. Dari penelitian yang telah dilakukan, efisiensi DSSC dengan ketebalan lapisan TiO2 berukuran 10 µm lebih besar jika dibandingkan dengan ketebalan lapisan 20 µm dan 30 µm. Hasil efisiensi DSSC tersebut yaitu 0.25% untuk ketebalan lapisan TiO2 berukuran 10 µm , 0,143% ketebalan lapisan TiO2 berukuran 20 µm, dan 0.195% untuk ketebalan lapisan TiO2 berukuran 30 µm.
Nanowire (NW) structures is an alternative candidate for constructing the next generation photoel... more Nanowire (NW) structures is an alternative candidate for constructing the next generation photoelectrochemical water splitting system, due to the outstanding optical and electrical properties. NW photoelectrodes comparing to traditional semiconductor photoelectrodes shows the comparatively shorter transfer distance of photo-induced carriers and the increase amount of the surface reaction sites, which is beneficial for lowering the recombination probability of charge carriers and improving their photoelectrochemical (PEC) performances. Here, we demonstrate for the first time that super-long Cu2O NWs, more than 4.5 μm, with highly efficient water splitting performance, were synthesized using a cost-effective anodic alumina oxide (AAO) template method. In comparison with the photocathode with planar Cu2O films, the photocathode with Cu2O NWs demonstrates a significant enhancement in photocurrent, from –1.00 to –2.75 mA/cm2 at –0.8 V versus Ag/AgCl. After optimization of the photoelectr...
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Papers by Agus Rubiyanto