Dionysius Santjojo
Brawijaya University, Physics, Faculty Member
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The plasma printing was used to make precise micro-texturing into the stainless steels to have complex textured geometry. First in this plasma printing, the original two dimensional micro-patterns were drawn onto the substrate surface by... more
The plasma printing was used to make precise micro-texturing into the stainless steels to have complex textured geometry. First in this plasma printing, the original two dimensional micro-patterns were drawn onto the substrate surface by the maskless patterning with use of the nano-carbon ink. These micro-patterned specimens were further plasma-nitrided at 673 K for 5.4 ks by 70 Pa with use of the hollow cathode device. The unprinted surface areas were selectively nitrided to have high nitrogen solute contents up to 12 mass%. The masked area just corresponded to the carbon-mapping from the printed nano-carbon inks, while the unprinted surface, to the nitrogen mapping. The hardness profile had stepwise change across the borders between these printed and unprinted areas; e.g., the hardness on the unprinted surface was 1200 Hv while it remained to be 350 Hv on the printed surface. This selective nitriding accompanied with the selective hardening. This selective nitriding enabled us to ...
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Abstract Nitrogen plasma treatment of a polystyrene layer in a vacuum chamber resulted in changes in its hydrophobicity properties. The purpose of this work was to investigate the effect of chamber pressure on nitrogen plasma treatment on... more
Abstract Nitrogen plasma treatment of a polystyrene layer in a vacuum chamber resulted in changes in its hydrophobicity properties. The purpose of this work was to investigate the effect of chamber pressure on nitrogen plasma treatment on the hydrophobicity properties of polystyrene surfaces. The plasma character was diagnosed by optical emission spectroscopy (OES) determining the plasma parameters, i.e. electron temperature (Te) and the electron density (Ne). Boltzmann plot method, ratio, and Stark Broadening were utilized to calculate the parameters. The hydrophobicity properties of polystyrene surfaces were measured by contact angle measurements, and polar groups studied with FTIR. The plasma diagnostic results showed that higher the chamber pressure resulted in greater intensity of the emission spectrum. The spectrum exhibits the highest intensity at the wavelength of 385.715 nm, indicating the existence of NII or N2+ ion species. The increase of the chamber pressure declined the electron temperature but increased the electron density. Results of the FTIR measurements indicated the presence of the new CH3 groups that are polar groups causing the surface to change characteristic, from hydrophobic to hydrophilic.
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Abstract Surface texturing of a carbon-based thin film is the critical technology in the development of functional surface for many kinds of sensors. This study explored the possibilities of processing the carbon film’s surface by means... more
Abstract Surface texturing of a carbon-based thin film is the critical technology in the development of functional surface for many kinds of sensors. This study explored the possibilities of processing the carbon film’s surface by means of plasma etching to produce micro-pillars. Circular dots with a diameter of 25 μm, 50 μm, and 100 μm were printed on a thick carbon film. A high density oxygen plasma was generated by a combination of RF and DC power in a vacuum chamber. The high density plasma was applied onto the surface of a diamond-like carbon film. The printed pattern serves as a mask-like in the lithography technique. The oxidation reaction was expected on the exposed surface, i.e. the area surrounded the dots. The results show the oxidation effectively removed the carbon on the unmasked area producing 3D circular patterns. The plasma processing, which was carried out for 2 h, was monitored and diagnosed using optical emission spectroscopy (OES). The oxidation was controlled by atomic oxygen which was the dominant species observed in the plasma. The removal (etching) rate was 9 μm/h with 91%, 98% and 99% pattern accuracy related to the larger diameter studied in this work. Observations using a Raman spectroscopy confirmed that the printed mask effectively protects the DLC from the etching process and other indirect processes.
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Carbon thin films on SKD11 steel were deposited by 40 kHz frequency plasma sputtering technique using a waste of battery carbon rods in argon plasma, and their mechanical properties were investigated by various target-substrate distances... more
Carbon thin films on SKD11 steel were deposited by 40 kHz frequency plasma sputtering technique using a waste of battery carbon rods in argon plasma, and their mechanical properties were investigated by various target-substrate distances (1 cm, 1.7 cm, 2 cm, and 2.4 cm). The power used is 340 watts, the vacuum time is 90 minutes, and the gas flow rate is 80 ml/minute. The deposition time of carbon in plasma sputtering is 120 minutes with the initial temperature (temperature during vacuum) of 28 oC and the final temperature (the temperature after plasma sputtering) is 300 oC. The hardness value of SKD11 steel deposited with carbon thin films on SKD11 with target-substrate distance was tested using the Vickers microhardness test. Testing the thickness of the carbon thin films on the SKD11 steel substrate was carried out using a Nikon type 59520 optical microscope. Qualitative analysis of the thickness of the carbon thin films on the SKD11 steel substrate at a scale of 20 μm is shown b...
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ABSTRACTNon-infrared-active hydrogen bonding species were investigated by analyzing the infrared spectra and the calibrated temperature desorption spectroscopy (CTDS) spectra of hydrogen released during degassing of hydrogenated amorphous... more
ABSTRACTNon-infrared-active hydrogen bonding species were investigated by analyzing the infrared spectra and the calibrated temperature desorption spectroscopy (CTDS) spectra of hydrogen released during degassing of hydrogenated amorphous silicon thin films. Samples were degassed gradually using a linear temperature ramp (0.5°C/s). Each stage corresponds to a temperature at which the hydrogen effusion peaks can be found (~ 340°C, ~ 500°C and ~ 610°C). Differences in the amounts of hydrogen obtained from the FTIR spectra and the CTDS measurement correspond to the non-infrared-active, occluded hydrogen.
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Citation: Sakti SP, Santjojo DJDH, Saputri SN, Aulanni'am (2012) Improvement of Biomolecule Immobilization on Polystyrene Surface by Increasing Surface Roughness. J Biosens Bioelectron 3:119. doi:10.4172/2155-6210.1000119 Copyright: ©... more
Citation: Sakti SP, Santjojo DJDH, Saputri SN, Aulanni'am (2012) Improvement of Biomolecule Immobilization on Polystyrene Surface by Increasing Surface Roughness. J Biosens Bioelectron 3:119. doi:10.4172/2155-6210.1000119 Copyright: © 2012 Sakti SP, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract Fast growing used of QCM biosensor has been reported. It is well known that the QCM sensor responses both to mass or viscosity changes. In its operation as mass sensitive sensor, a QCM responses to the mass change per surface area. In the use of QCM biosensor, immobilization of the bio sensitive layer on top of the sensor surface is one of the importance factors. The immobilization of the biomolecule can be done directly on top of the sensor electrode or by using a coating material as s...
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... How to Cite. Clare, B., Jennings, P., Cornish, J., Hefter, GT and Santjojo, DJ (1996), Simulation of the infrared spectra of amorphous silicon alloys. ... Author Information. School of Mathematical and Physical Sciences, Murdoch... more
... How to Cite. Clare, B., Jennings, P., Cornish, J., Hefter, GT and Santjojo, DJ (1996), Simulation of the infrared spectra of amorphous silicon alloys. ... Author Information. School of Mathematical and Physical Sciences, Murdoch University, Murdoch WA 6150, Australia. ...
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A functional layer is crucial in a QCM sensor, to immobilize target molecules. The microstructure of the layer determines the sensitivity of the sensor. On the other hand, the microstructure also affects the loading of the sensor. In this... more
A functional layer is crucial in a QCM sensor, to immobilize target molecules. The microstructure of the layer determines the sensitivity of the sensor. On the other hand, the microstructure also affects the loading of the sensor. In this study, impedance analysis was used to investigate the relationship between the microstructure and the viscoelastic properties of a petalous stearic acid (SA) functional layer. The SA layer was deposited using a vacuum thermal evaporation technique. Different petalous pillar structures in the elastic layer were generated by varying the deposition time. Analysis showed that the growth of the embedded pillar structures dramatically reduced the conductance and increased the bandwidth. The energy dissipation during the vibration could be related to the interaction between the pillars and the elastic matrix.
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Air sterilizer is one of the essential components in combating the Covid-19. A wind tunnel model of the air sterilizer using a dielectric barrier discharge plasma is proposed to destroy the virus by direct contact with the plasma.... more
Air sterilizer is one of the essential components in combating the Covid-19. A wind tunnel model of the air sterilizer using a dielectric barrier discharge plasma is proposed to destroy the virus by direct contact with the plasma. Dangerous ozone production in the plasma reactor should be controlled to a safe level. Two parameters affecting the ozone concentration, i.e., electrical power and airflow, were investigated. The DBD reactor was a cell constructed from an array of alternate electrodes. The plasma was generated by an AC high voltage generator with a range of 2kV -3kV. The power and the high voltage were varied by controlling the DC input voltage of the generator. The airflow was varied by controlling the speed of an exhaust fan from 0.5 m/s to 3.0 m/s. The state was characterized using optical emission spectroscopy in the range of 200 nm – 1000 nm. The results showed that both parameters played a significant role in ozone concentration. The trend of the ozone is strongly co...
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The wettability of material can change from hydrophobic to hydrophilic when treated using plasma nitrogen. The present work investigated the influence of the plasma treatment duration on the modification of polystyrene’s surface coating... more
The wettability of material can change from hydrophobic to hydrophilic when treated using plasma nitrogen. The present work investigated the influence of the plasma treatment duration on the modification of polystyrene’s surface coating on a glass surface. The polystyrene layer was produced by means of spin coating method with the rotational speed of 3000 RPM for 1 minute. The plasma was established by a 2 MHz RF generator at the power of 40 watts, pressure of 0.3 Torr, flow rate 40 mL/min. The samples were treated at various exposure time which were 2 min, 5 min, 10 min, and 15 min. The wettability of the polystyrene was measured using a contact angle measurement before and after the nitrogen plasma treatment. Polar functional groups related to the wettability were observed by a Fourier Transform Infrared (FTIR). The longer the treatment duration, the smaller the contact angle was observed. A very low contact angle of 6.42° was achieved at a power of 40 watt at 0.3 torr for the exp...
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In this research, a modified QCM surface was done to improve the performance of QCM biosensors. This modification is done by coating polystyrene (Ps) on a QCM with toluena and chloroform solvents. The polystyrene coating was performed... more
In this research, a modified QCM surface was done to improve the performance of QCM biosensors. This modification is done by coating polystyrene (Ps) on a QCM with toluena and chloroform solvents. The polystyrene coating was performed using spin coating technique, the measurement of surface roughness values using non-contact topography measurement system TMS 1200, and the viscoelastic properties was analyzed by using an electrical impedance. The analysis result using TMS 1200 shows morphologies of polystyrene produced with chloroform solvent have groovier and more porous compared to the toluena solvent. The roughness values of Ps surface with choroform and toluena is about 616.52 nm and 578.9 nm, respectively. The different surface roughness both of the solvent is caused by vapor pressure of each solvent. The vapor pressure value of chlorofrom solvent is 0.26 atm and toluena solvent of 0.037 atm. Moreover, using Sauerbrey equation is found mass of deposited ps produced with chlorofo...
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One pot in-situ co-precipitation of chitosan-Fe3O4 nanoparticles as a candidate of drug delivery agent have been synthesized using combination of tripolyphosphate (TPP)/citrate as cross-linkers. The aim of this study was to determine the... more
One pot in-situ co-precipitation of chitosan-Fe3O4 nanoparticles as a candidate of drug delivery agent have been synthesized using combination of tripolyphosphate (TPP)/citrate as cross-linkers. The aim of this study was to determine the effect of preparation process towards chitosan-Fe3O4 nanoparticles characteristics. Chitosan-Fe3O4 nanoparticles were prepared on various preparation condition including Chitosan:Fe(II):Fe(III) ratio, TPP:citrate ratio, and cross-linking time. The X-ray diffraction result shows that the phase contained in nanoparticles produced is mostly Fe3O4 phase, since the diffraction peaks of the samples were consistent with the database in crystalline pattern of the Fe3O4 phase in ICSD#26410. The percentage of Fe3O4 was obtained from Materials Analysis Using Diffraction (MAUD) program. The presence of chitosan prevents the oxidation of Fe3O4, as evidenced by larger percentage of Fe3O4 in chitosan-Fe3O4 nanoparticles than bare Fe3O4. The combination of TPP:citr...
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The thickness measurement of PS thin films on QCM surface and ZnPc layer on QCM/PS using Sauerbrey equation and Scanning Electron Microscope (SEM) has been investigated. Calculation result using a modified Sauerbrey equation show the... more
The thickness measurement of PS thin films on QCM surface and ZnPc layer on QCM/PS using Sauerbrey equation and Scanning Electron Microscope (SEM) has been investigated. Calculation result using a modified Sauerbrey equation show the thickness of PS layer and ZnPc one are 0,45 μm and 0,0676 μm respectively. Additionally the thickness measurement by using SEM shows the thickness of PS layer is 5,33 μm and the thickness of ZnPc layer is 10,44 μm. The differences thickness between Sauerbrey equation and SEM topograph is due to layers porosity. The topography of thin films produced by the secondary electron beam scanning allows to get a magnification of SEM image so that it can be measured directly. While the thickness calculation using the Sauerbrey equation is based on the change in the resonance frequency of QCM.
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A hollow cathode has been one of the methods to intensify the plasma in the etching or ashing process. This work examined a number of technologies in the intensification of a 2 MHz RF glow discharge plasma to deposit carbon film by means... more
A hollow cathode has been one of the methods to intensify the plasma in the etching or ashing process. This work examined a number of technologies in the intensification of a 2 MHz RF glow discharge plasma to deposit carbon film by means of the hollow cathode. Three types of the cathode configurations, which were cylindrical, rectangular and a cylindrical-rectangular combination, were tested to get an optimum condition for the carbon deposition. Both carbon target and substrate were fixed inside the hollow cathode. The plasma was characterized by means of optical emission spectroscopy (OES) at the range of 200 nm – 1000 nm. The results showed that the combination where the rectangular hollow was placed inside the cylindrical one, produced the most intense glow. Ion density and electron temperature in the plasma were determined by a calculation based on the atomic data related to the specific electronic transitions of the ions. The density of ions was very high in the centre area of ...
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Pyrolytic graphite with the vertically oriented graphene (VG) planes along the thickness has grown up as one of the most exotic materials. Its high thermal conductivity and high specific strength were suitable for electronic components.... more
Pyrolytic graphite with the vertically oriented graphene (VG) planes along the thickness has grown up as one of the most exotic materials. Its high thermal conductivity and high specific strength were suitable for electronic components. The micro-textures were necessary to join the VG for heat distribution with the transistors for packaging into an electronic device. In the present study, the high-density oxygen plasma etching was utilized to make micro-texturing into the VG specimen. The micro-lines were drawn onto the VG surface as a mask. The hollow-cathode oxygen plasma was utilized to intensify the high oxygen ion and electron densities for the etching process. The sharp-edge profile was formed on the surface of VG after etching process for 7.2 ks. This high etching rate was attained to be 13 µm/h for the VG specimen. The locally disordered substructure on the etched surface was detected by using the Raman spectroscopy. The electrical resistivity was observed in the etched and masked area of VG specimen after the etching process.
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Nitrogen plasma treatment was carried out to modify the surface of polystyrene film deposited on a quartz crystal microbalance (QCM) sensor. The modification was intended to enhance the wettability of the film by inducing the formation of... more
Nitrogen plasma treatment was carried out to modify the surface of polystyrene film deposited on a quartz crystal microbalance (QCM) sensor. The modification was intended to enhance the wettability of the film by inducing the formation of CN functional group on its surface. This work investigated the effect of DC bias controlling N* in the plasma on the effectiveness of the nitrogen plasma treatment. The polystyrene was deposited by a spin coating method on the surface of a quartz crystal normally used in an electronic resonator. The nitrogen plasma was generated in an aluminium vacuum chamber using a 2 MHz radio frequency (RF) generator. The vacuum pressure and the gas flow rate were kept constant during the experiments. The plasma character in the chamber was controlled by applying a DC bias between the RF electrodes and the sample stage. The DC voltage was varied from 100 to 500 volts at 100 volts’ step, while maintaining the RF voltage constant. During the process, the species i...
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ABSTRACT A control system has evolved from a traditional approach to a fuzzy and neural network based system. The system development is intended to achieve a good response and stability. In current technology many control systems are... more
ABSTRACT A control system has evolved from a traditional approach to a fuzzy and neural network based system. The system development is intended to achieve a good response and stability. In current technology many control systems are implemented using a digital system. By using a microcontroller we have developed a simple control system based on classical control, combining an ON–OFF controller and PI (proportional integral) or PID (proportional integral derivative) controller to control a substrate heater’s temperature. The system will act as an ON–OFF or PI/PID control depending on the temperature difference between the setting point and substrate heater temperature. The approach has been successfully implemented to control substrate temperature with a characteristic of a fast response at the beginning and a stable response at steady state.
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... ELSEVIER Thin Solid Films 310 (1997) 156-I60 A study of the effects of annealing and outgassing on hydrogenated amorphous silicon PJ Jennings *, JCL Cornish, BW Clare, GT Hefter, DJ Santjojo Department of Physics and Energy Studies,... more
... ELSEVIER Thin Solid Films 310 (1997) 156-I60 A study of the effects of annealing and outgassing on hydrogenated amorphous silicon PJ Jennings *, JCL Cornish, BW Clare, GT Hefter, DJ Santjojo Department of Physics and Energy Studies, Murdoch University, Murdoch ...
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In this work, we apply optical emission spectroscopy to investigate active plasma species to study that plasma nitrogen treatment affects polystyrene surfaces. Data concerning these active plasma species are crucial for exploring the... more
In this work, we apply optical emission spectroscopy to investigate active plasma species to study that plasma nitrogen treatment affects polystyrene surfaces. Data concerning these active plasma species are crucial for exploring the polystyrene layer's functionality deposited on quartz crystal microbalance (QCM) surface. Wettability function in biosensors development is essential aspects for biomolecule immobilization. The surface of the polystyrene layer was modified by plasma nitrogen treatment. The process parameters affecting plasma species and characteristic, and hence the treatment results studied in this work were chamber pressure, flow rate, and DC bias. The plasma analysis was conducted by optical emission spectroscopy. The spectroscopy was utilized to predict the active species of plasma, the electron temperature Te and the electron density Ne. The dominant reactive species was N2+ which go through different plasma interactions and on the polystyrene surface depending...
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Diamond-like carbon (DLC) has been widely utilized in industries; e.g., the protective coating of punches and dies. The high-density plasma oxidation was used to make selective removal of the DLC films and to construct the... more
Diamond-like carbon (DLC) has been widely utilized in industries; e.g., the protective coating of punches and dies. The high-density plasma oxidation was used to make selective removal of the DLC films and to construct the three-dimensional micro-texture on the SKD11. Two-dimensional micro-texture was drawn onto these films via the maskless lithography patterning. Micro-dots with various diameters were utilized as a mask to make selective removal of unmasked DLC surfaces. The optical emission spectroscopy (OES) was used to make oxygen plasma diagnosis and to identify the active species for this plasma etching. The Raman spectroscopy was employed to analyze the masked and unmasked area after the etching process. The etching took place homogeneously within 7.2 ks process. The three-dimensional micro-texture of DLC was formed with the height of $18\ \mu \mathrm{m}$. The formed micro-textures have a standard deviation less than $1\ \mu \mathrm{m}$.
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On type of Plasma is a Plasma DBD which is generated at atmospheric pressure. Scaffold hydroxyapatite (HA) is a bioceramic which widely developed nowadays in applications. The pores that are owned in the scaffold can effect a mechanical... more
On type of Plasma is a Plasma DBD which is generated at atmospheric pressure. Scaffold hydroxyapatite (HA) is a bioceramic which widely developed nowadays in applications. The pores that are owned in the scaffold can effect a mechanical properties, namely compressive strength. Treatment by using Plasma DBD method is expected to have a good improvement to interconnected porous so as to improve the compressive strength of the bioceramic scaffold HA. In this study, we use 3 different time variations are 20 minutes, 25 minutes dan 30 minutes in Plasma DBD treatment to determine the effect of each variations. Pore analysis and compressive strength test will be carried out before and after Plasma DBD treatment. The surface morphology of the scaffold HA was observed by using a Field Emission – Scanning Electron Microscope (FE-SEM), composition by using EDX and compressive strength was observed by using compressive strength test. The result showed that the compressive strength of bioceram...
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Pengukuran jarak dengan menggunakan tranduser ultrasonik termasuk dalam pengukuran non kontak. Metode yang sering digunakan dalam pengukuran jarak menggunakan tranduser ultrasonik adalah metode pulsa-echo dan metode korelasi silang.... more
Pengukuran jarak dengan menggunakan tranduser ultrasonik termasuk dalam pengukuran non kontak. Metode yang sering digunakan dalam pengukuran jarak menggunakan tranduser ultrasonik adalah metode pulsa-echo dan metode korelasi silang. Metode pulsa-echo adalah metode yang didasarkan pada pengukuran waktu tempuh gelombang ultrasonik. Sedangkan metode korelasi silang didasarkan pada korelasi antara dua gelombang yakni gelombang ultrasonik kirim dan gelombang ultrasonik terima. Penelitian ini melakukan pengukuran jarak menggunakan metode pulsa-echo dan membandingkannya dengan hasil dari metode korelasi silang. Pengambilan data dilakukan setiap pertambahan jarak 0,01 melebihi 1 panjang gelombang ultrasonik. Hasil pengambilan data menunjukkan bahwa metode pulsa-echo memiliki tingkat akurasi dan presisi pengukuran jarak yang cukup baik.
Arterial pulse signal reading by a therapist in Traditional Chinese Medicine (TCM) requires considerable experience and thoroughness. The interpretation resulted by the therapist is very subjective. The objectivity of the device can be... more
Arterial pulse signal reading by a therapist in Traditional Chinese Medicine (TCM) requires considerable experience and thoroughness. The interpretation resulted by the therapist is very subjective. The objectivity of the device can be achieved by increasing the accuracy and the consistency of the reading in the range of 1-2 Hz. An electret condenser microphone (ECM) can be used as a pulse sensor in such device. This study reveals that ECM performs a number of advantages such as small-sized and inexpensive. Unfortunately, this ECM also picks up mechanical noises during direct contact with the subject. This study proposed soft silicon rubber as a medium between subjects and ECM. The technique was designed to enhance the mechanical coupling between the ECM and the source signal without affecting the signal source. The results show that the ECM could measure the signal of 0.5-10 Hz with the average accuracy of 99,47%.
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Functionality of zinc pthalocyanine (ZnPc) thin film for immobilization of biomolecules was studied using bovine serum albumin (BSA). The functionality is affected by microstructures and surface roughness of the film. This studies is... more
Functionality of zinc pthalocyanine (ZnPc) thin film for immobilization of biomolecules was studied using bovine serum albumin (BSA). The functionality is affected by microstructures and surface roughness of the film. This studies is conducted by producing ZnPc films by means of thermal evaporation in vacuum. The ZnPc films were deposited on quartz crystal substrates with a polystyrene interlayer. Observations were carried out using a scanning electron microscope and an optical micro-profilometry. Enhancement of the functionality is observed with the increase of the film thickness. Surface roughness and microstructures of the film influence the functionality in a complex way. Adsorbtion of the BSA molecules is associated with both the surface roughness and microstructures. Although generally the adsorption is proportional to the contact area but the roughness and fibrous microstructures of the deposited ZnPc produce complex adsorption and trapping mechanisms in the immobilization of the BSA.