A.S.M. Mohsin - Academia.edu (original) (raw)

Papers by A.S.M. Mohsin

Study the optical property of gold nanoparticle and apply them to design bowtie nanoantenna using FDTD simulation

Journal of Optics, 2022

Pneumothorax Segmentation from Chest X-Rays Using U-Net/U-Net++ Architectures

2022 First International Conference on Electrical, Electronics, Information and Communication Technologies (ICEEICT)

Energy Demand Forecasting Using Machine Learning Perspective Bangladesh

2023 IEEE IAS Global Conference on Renewable Energy and Hydrogen Technologies (GlobConHT)

Optics Express, 2014

In this paper we demonstrate multilayer fabrication of plasmonic gold nanorod arrays using electr... more In this paper we demonstrate multilayer fabrication of plasmonic gold nanorod arrays using electron-beam lithography (EBL), and show that this structure could be used for multilayered optical storage media capable of continuous-wave (cw) laser readout. The gold nanorods fabricated using the EBL method are aligned perfectly and homogeneous in size and shape, allowing the polarization response of surface plasmon resonance (SPR) to be observed through ensemble array. This property in turn permits polarization detuned SPR readout possible and other manipulations such as progressively twisted arrays through the multilayers to make cw readout possible through deeper layers without too much extinction loss. The layered gold nanorod arrays are separated by thick spacer layer to enable the optical resolving of individual layers. Using this method, we demonstrated four-fold reduction in extinction loss for cw readout in three-layer structure. The current technique of multilayer fabrication and readout can be useful in 3-dimensional fabrication of plasmonic circuits and structures.

IOP Conference Series: Materials Science and Engineering

Concerns regarding the negative impact towards environment due to the increasing use of natural s... more Concerns regarding the negative impact towards environment due to the increasing use of natural sand in construction industry and dumping of industrial solid wastes namely coal bottom ash (CBA) and oil palm shell (OPS) has resulted in the development of environmental friendly lightweight concrete. The present study investigates the effect of coal bottom ash as partial fine aggregate replacement towards workability and compressive strength of oil palm shell lightweight aggregate concrete (OPS LWAC). The fresh and mechanical properties of this concrete containing various percentage of coal bottom ash as partial fine aggregate replacement were investigated. The result was compared to OPS LWAC with 100 % sand as a control specimen. The concrete workability investigated by conducting slump test. All specimens were cast in form of cubes and water cured until the testing age. The compressive strength test was carried out at 7 and 28 days. The finding shows that integration of coal bottom ash at suitable proportion enhances the strength of oil palm shell lightweight aggregate concrete.

A comparative analysis between the Step Index fiber and Polarization Maintaining fiber on the basis of their modal solutions

2010 International Conference on Electronics and Information Engineering, 2010

This paper reviews a modal solution of the single mode Step Index fiber and Polarization Maintain... more This paper reviews a modal solution of the single mode Step Index fiber and Polarization Maintaining fiber based on the analysis and simulation with FEM lab which reflects a significant way of propagating signals with less power consumptions as the ...

A Proposed Design for The Development of Vital Sign(Electrocardiogram) Patient Monitoring System

The vital signs monitor is essentially a real time device that displays certain received signals ... more The vital signs monitor is essentially a real time device that displays certain received signals from the human body. It is widely used in medical institutes. The projects of this sort under taken so far have used windows to display the output whereas this project aims to generate a real time display of the signals received from the human body using Linux. Linux was preferred for its ability to simultaneously process data and display it in real time. This includes creating appropriate sensors, proper modifying circuits and ensuring real time display. The project has a channel for the variable that will be continuously measured and displayed by the device. The variable is electrocardiogram.

For transmission of large amounts of electric power, AC in the overwhelming majority of cases is ... more For transmission of large amounts of electric power, AC in the overwhelming majority of cases is the established as well as the most cost effective option at hand. In cases of long distance transmission, as in interconnection of power systems, care has to be taken for safeguarding of synchronism as well as stable system voltages in the interconnection, particularly for extreme load conditions and in conjunction with system faults. Use of Thyristor Controlled Series Capacitor (TCSC) as Flexible AC Transmission System (FACTS) device brings a number of benefits for the user of the grid, all contributing to an increase of the power transmission capability of new as well as existing transmission lines. These benefits include improvement in system stability, voltage regulation, reactive power balance, load sharing between parallel lines and reduction in transmission losses.

Light trapping in thin-film solar cell to enhance the absorption efficiency using FDTD simulation

Journal of Optics

Recently, plasmonics has been used to trap the light at nanoscale to improve the absorption in so... more Recently, plasmonics has been used to trap the light at nanoscale to improve the absorption in solar cells. In this study, we construct a silicon thin-film solar cell (TFSC) using finite-difference time-domain (FDTD) simulation. The TFSC solar cell was designed with TiO2 anti-reflection layer, aluminum (Al) as a reflective layer, and silicon (Si) as a absorption layer. The silver nanoparticles of 50 nm diameter and 400 nm separation are embedded on absorption layer. Optimizing the location of nanoparticle, light scattering efficiency and near-filled light concentration has been harnessed. The reflective Al layer reflect the light towards upper layer and increases the overall absorption. The proposed structure allows the sunlight to enter into the absorption layer at all directions, breaking the molecular bonding and releasing electrons. We determined the short-circuit current, fill factor, open-circuit voltage, absorption efficiency, and conversion efficiency of our proposed model. The simulation results reveals that, TFSC with embedded nanoparticle array, antireflection coating and reflective layer has higher short-circuit current of 23.98 mA/cm2, higher fill-factor of 0.84 and an efficiency of 12.3%.The proposed TFSC solar cell increases the absorption efficiency by 43.5% and conversion efficiency by 64.66% compared with conventional TFSC. The findings will be helpful to design more efficient and cost effective solar cell utilizing light-trapping mechanism of plasmonic nanoparticle of different size, shape, and geometry.

Design and Development of IoT Based Accident Detection and Emergency Response System

Proceedings of the 2020 5th International Conference on Cloud Computing and Internet of Things

The number of road accidents is increasing at a rapid pace which also affects the death rate that... more The number of road accidents is increasing at a rapid pace which also affects the death rate that is proportional to the number of accidents occurring. This is a serious issue that has unfortunately become somewhat normalized due to how deeply embedded it is in the day-to-day lives of people, especially in developing countries. For any society to make significant progress, it is imperative to utilize our technical skills or otherwise to ensure personal safety before anything else. This includes reducing the time of response to an accident to the minimum, among other things. The development of the Internet of Things (IoT) based accident detection and response system is an attempt towards minimizing the rates of casualty and injuries occurring to both passengers and vehicles due to road accidents. The system is fully automated to be able to send emergency notifications to nearby hospital or fire station and an emergency contact in case of an accident. This is done via a combination of a vehicle device that has to be installed in the vehicle of the consumer and a remote server system that responds to the device accordingly. The motive is to provide the location of the vehicle and measure the severity of the accident so that help can be provided as fast as possible. From the data values collected from the sensors in the vehicle device prototype, we have tested the notification process successfully and also been able to assess the level of accident severity. We believe this system will reduce the response time of emergency responders and in the process improve both the traffic and health system of a society.

International Journal of Nanomedicine, Oct 1, 2018

Background: We have introduced a novel method to quantify the intracellular refractive index (RI)... more Background: We have introduced a novel method to quantify the intracellular refractive index (RI) of living cells and determine the molecular interaction of two interacting molecules using single particle spectroscopy. The advantages of this proposed technique over fluorescence-based imaging techniques is that it does not require any contrasting agent and it does not blink and bleach. Instead, our technique provides a non-destructive, non-invasive, high-resolution imaging of live cells. Methods: To verify our technique, we initially tested our approach for a dielectric medium where gold nanoparticles (AuNPs) were embedded in a polyvinyl alcohol (PVA) matrix, which was then extended to the cellular environment. In the dielectric medium, we identified the single particle and dimer and determined the interparticle distance of AuNPs using confocal laser scattering microscopy. We also determined the single particle RI from dark-field scattering microscopy images, which was confirmed with Mie theory and finite-difference time-domain (FDTD) simulated results. The single particle spectroscopy and microscopy technique was then extended to determine the intracellular RI and biomolecular interaction inside living cells using hyperspectral imaging and dark-field scattering microscopy. Results: The novelty of the paper lies in the demonstration of a direct and accurate method to probe the intracellular RI and molecular interaction focused on single particle analysis whereas previous demonstrations were based on AuNP ensembles. Optically acquired single particle and dimer images was verified by correlated SEM images also optical spectrum with analytical models and FDTD simulations for both the dielectric and cellular environment. We reported the interparticle distance of AuNPs inside HeLa cells and intracellular refractive index, which was also confirmed with Mie Theory and extensive FDTD simulations. Conclusion: Moreover, we believe that our in-depth plasmonic NP-based alternate imaging technique will provide a new insight in monitoring cellular dynamics and tracking the targeted NPs within live cells, enabling us to use plasmonic NPs as an intracellular biosensor.

IEEE Photonics Journal

In this paper, we investigated the plasmon coupling, quantum yield (QY) and effect of tip geometr... more In this paper, we investigated the plasmon coupling, quantum yield (QY) and effect of tip geometry of gold nanoparticles (AuNPs) using finite-difference time-domain (FDTD) simulation. Standalone AuNPs spectra have been obtained using the most reliable electromagnetic theory such as Mie theory for spherical nanoparticle such as gold nanosphere (AuNS) and Mie-Gans theory for ellipsoidal AuNPs such as gold nanorod (AuNR). We reported the scattering cross section for standalone and coupling particle using the modified dielectric constant, where the size effect of small particles and the retardation effect of large particles have been taken into consideration for both the analytical calculation and FDTD simulation. Plasmon coupling effect of AuNS dimer of 80-nm diameter and AuNR dimer (side-by-side geometry) of aspect ratio 3.8 has been investigated using FDTD simulation. We also quantified the QY in terms of cluster to monomer ratio for AuNS and AuNR, which is analogous to the ratio of acceptor and donor chromophore in biological systems. The QY of monomer, dimer, and trimer of 40-nm diameter AuNS has been perceived using FDTD simulation, integrating the whole spectrum over 400-1000 nm wavelength regime. Additionally, effect of tip geometry of AuNPs has been investigated and significant field enhancement due to the variation in shapes such as AuNS, AuNR, gold dumbbell, and gold bipyramid has also been reported. The novelty of the paper lies in the presentation of a systematic study of the plasmon coupling of different sizes and shapes of AuNP, quantification of the QY, and probing the effect of tip geometry for a single material such as AuNP using the FDTD simulation. Moreover, we believe that our in-depth analysis of AuNP laid the foundation to determine the scattering cross-section, QY, and near-field enhancement for more complex structures and geometries of other novel materials. Conclusively, the investigation results demonstrate that plasmonic nanoparticle can be used as a molecular probe for bioimaging, sensing, cell signaling, and biological therapeutic intervention.

ACS applied materials & interfaces, Jan 10, 2017

In this manuscript, we report the refractive-index (RI) modulation of various concentrations of n... more In this manuscript, we report the refractive-index (RI) modulation of various concentrations of nitrogen-doped carbon dots (N@C-dots) embedded in poly(vinyl alcohol) (PVA) polymer. The dispersion and size distribution of N@C-dots embedded within PVA have been investigated using electron microscopy. The RI of PVA-N@C-dots can be enhanced by increasing the doping concentration of highly-fluorescent C-dots (quantum yield 44%). This is demonstrated using ultraviolet-visible (UV-visible), photoluminscence, Raman, and Fourier transform infrared (FTIR) spectroscopy measurements. The Mie-scattering of light on N@C-dots was applied for developing the relationship between RI tuning and absorption cross section of N@C-dots. The extinction cross-section of N@C-dot thin films can be rapidly enhanced by either tuning the RI, or by increasing the concentration of N@C-dots. The developed method can be used as effective RI contrast for various applications such as holography creation and bio-imaging.

Bio-Medical Engineering (BME) has been an active research area for years. BME is the application ... more Bio-Medical Engineering (BME) has been an active research area for years. BME is the application of engineering techniques to the medical fields. It combines the design and problem solving skills of engineering with medical sciences to improve the health care and the quality of individual life. With the proliferation of advanced electronics and applied engineering, the ways to help people specifically patients are changed. Therefore, an advanced design for monitoring a vital sign towards experimentation is presented. The vital signs monitor is essentially a real time device that displays certain received signals from the human body. The projects of this sort under taken so far have used windows to display the output whereas this project aims to generate a real time display of the signals received from the human body using Linux. Linux was preferred for its ability to simultaneously process data and display it in real time. The basic principles and methods are outlined. The major components of the system are shown separately, and are discussed individually. Few electronic devices used for data are depicted and described. The final results show a better performance

The aim of this PhD was to develop a technique to quantify the uptake and aggregation of gold nan... more The aim of this PhD was to develop a technique to quantify the uptake and aggregation of gold nanoparticles (AuNPs) using image correlation spectroscopy (ICS). We proposed a non - destructive microscopic optical method using image correlation spectroscopy (ICS) together with plasmon coupling. The combination of these techniques provides an indication of what is happening within cells, both at the microscopic and macroscopic level. This technique could be used in different biological applications including cancer therapy, drug delivery, disease diagnosis and also for probing membrane protein stoichiometry and dynamics. Although visual resolution itself may not be improved, the ability to ‘see’ inside cells may be enhanced by the use of the methods discovered here.

2010 2nd International Conference on Mechanical and Electronics Engineering, 2010

Utilization of renewable energy resources have been the most important & prospective field to see... more Utilization of renewable energy resources have been the most important & prospective field to seek new energy sources to meet up the increasing demand in power all over the world specially in a developing country like Bangladesh. Among the renewable resources, wind & solar being the most popular ones due to abundant, ease of accessibility and convertibility to the electricity. This paper presents the analysis and design of a hybrid solar-wind system for micro generation for domestic purpose in the rural & remote areas of our country where continuous power supply from central grid has been a great is problem and sometimes for some remote places it's economically not viable at all as far as our country is concerned. We propose such a hybrid system which is expected to run effectively under a microcontroller to utilize the maximum possible solar & wind resources to reduce the demands on national grid for on-grid region as well as to supply power to those places where there is no grid line (i.e. off-grid region).

International Journal of Nanomedicine, 2013

Aqueous solutions of ultra-pure gold nanoparticles have been prepared by methods of femtosecond l... more Aqueous solutions of ultra-pure gold nanoparticles have been prepared by methods of femtosecond laser ablation from a solid target and fragmentation from already formed colloids. Despite the absence of protecting ligands, the solutions could be (1) fairly stable and poly size-dispersed; or (2) very stable and monodispersed, for the two fabrication modalities, respectively. Fluorescence quenching behavior and its intricacies were revealed by fluorescence lifetime imaging microscopy in rhodamine 6G water solution. We show that surface-enhanced Raman scattering of rhodamine 6G on gold nanoparticles can be detected with high fidelity down to micromolar concentrations using the nanoparticles. Application potential of pure gold nanoparticles with polydispersed and nearly monodispersed size distributions are discussed.

A comparative analysis between the Step Index fiber and Polarization Maintaining fiber on the basis of their modal solutions

2010 International Conference on Electronics and Information Engineering, 2010

Abstract This paper reviews a modal solution of the single mode Step Index fiber and Polarization... more Abstract This paper reviews a modal solution of the single mode Step Index fiber and Polarization Maintaining fiber based on the analysis and simulation with FEM lab which reflects a significant way of propagating signals with less power consumptions as the ...

International Journal of Engineering and Technology, 2011

Energy is one of the main concerns for the growing future of any nation. Energy is by far the lar... more Energy is one of the main concerns for the growing future of any nation. Energy is by far the largest merchandise in the world and an enormous amount of energy is extracted, distributed, converted and consumed in our global society daily. The per capita energy consumption of Bangladesh is one of the lowest amongst the sub continent. Despite only 32% population has access to the National grid, The Government of Bangladesh a noble vision to provide electricity for all by the year 2020.Target of meeting 5% of total electricity demand from RE by 2010 and 10% by the year 2020 .In crisis conditions energy usage should be appropriate and meticulous. Our technology for energy harvest, conversion and efficient application is still lacking behind with that of developed world. We should give emphasis for the development of indigenous technology. Bangladesh is situated between 20.30 and 26.38 degrees north latitude and 88.04 and 92.44 degrees east longitude, which is an ideal location for solar energy utilization. Daily solar radiation varies between 4 and 6.5 kWh/m2.In this regard, solar dryer for domestic as well industrial usage could be an effective alternative of saving conventional energy. Utilization of solar thermal energy through solar dryer is relatively in a nascent state in our country. The objective of this paper is the design & performance analysis of different types of solar dryer & its prospect in Bangladesh.

In this paper we demonstrate multilayer fabrication of plasmonic gold nanorod arrays using electr... more In this paper we demonstrate multilayer fabrication of plasmonic gold nanorod arrays using electron-beam lithography (EBL), and show that this structure could be used for multilayered optical storage media capable of continuous-wave (cw) laser readout. The gold nanorods fabricated using the EBL method are aligned perfectly and homogeneous in size and shape, allowing the polarization response of surface plasmon resonance (SPR) to be observed through ensemble array. This property in turn permits polarization detuned SPR readout possible and other manipulations such as progressively twisted arrays through the multilayers to make cw readout possible through deeper layers without too much extinction loss. The layered gold nanorod arrays are separated by thick spacer layer to enable the optical resolving of individual layers. Using this method, we demonstrated four-fold reduction in extinction loss for cw readout in three-layer structure. The current technique of multilayer fabrication and readout can be useful in 3-dimensional fabrication of plasmonic circuits and structures.

Study the optical property of gold nanoparticle and apply them to design bowtie nanoantenna using FDTD simulation

Journal of Optics, 2022

Pneumothorax Segmentation from Chest X-Rays Using U-Net/U-Net++ Architectures

2022 First International Conference on Electrical, Electronics, Information and Communication Technologies (ICEEICT)

Energy Demand Forecasting Using Machine Learning Perspective Bangladesh

2023 IEEE IAS Global Conference on Renewable Energy and Hydrogen Technologies (GlobConHT)

Optics Express, 2014

In this paper we demonstrate multilayer fabrication of plasmonic gold nanorod arrays using electr... more In this paper we demonstrate multilayer fabrication of plasmonic gold nanorod arrays using electron-beam lithography (EBL), and show that this structure could be used for multilayered optical storage media capable of continuous-wave (cw) laser readout. The gold nanorods fabricated using the EBL method are aligned perfectly and homogeneous in size and shape, allowing the polarization response of surface plasmon resonance (SPR) to be observed through ensemble array. This property in turn permits polarization detuned SPR readout possible and other manipulations such as progressively twisted arrays through the multilayers to make cw readout possible through deeper layers without too much extinction loss. The layered gold nanorod arrays are separated by thick spacer layer to enable the optical resolving of individual layers. Using this method, we demonstrated four-fold reduction in extinction loss for cw readout in three-layer structure. The current technique of multilayer fabrication and readout can be useful in 3-dimensional fabrication of plasmonic circuits and structures.

IOP Conference Series: Materials Science and Engineering

Concerns regarding the negative impact towards environment due to the increasing use of natural s... more Concerns regarding the negative impact towards environment due to the increasing use of natural sand in construction industry and dumping of industrial solid wastes namely coal bottom ash (CBA) and oil palm shell (OPS) has resulted in the development of environmental friendly lightweight concrete. The present study investigates the effect of coal bottom ash as partial fine aggregate replacement towards workability and compressive strength of oil palm shell lightweight aggregate concrete (OPS LWAC). The fresh and mechanical properties of this concrete containing various percentage of coal bottom ash as partial fine aggregate replacement were investigated. The result was compared to OPS LWAC with 100 % sand as a control specimen. The concrete workability investigated by conducting slump test. All specimens were cast in form of cubes and water cured until the testing age. The compressive strength test was carried out at 7 and 28 days. The finding shows that integration of coal bottom ash at suitable proportion enhances the strength of oil palm shell lightweight aggregate concrete.

A comparative analysis between the Step Index fiber and Polarization Maintaining fiber on the basis of their modal solutions

2010 International Conference on Electronics and Information Engineering, 2010

This paper reviews a modal solution of the single mode Step Index fiber and Polarization Maintain... more This paper reviews a modal solution of the single mode Step Index fiber and Polarization Maintaining fiber based on the analysis and simulation with FEM lab which reflects a significant way of propagating signals with less power consumptions as the ...

A Proposed Design for The Development of Vital Sign(Electrocardiogram) Patient Monitoring System

The vital signs monitor is essentially a real time device that displays certain received signals ... more The vital signs monitor is essentially a real time device that displays certain received signals from the human body. It is widely used in medical institutes. The projects of this sort under taken so far have used windows to display the output whereas this project aims to generate a real time display of the signals received from the human body using Linux. Linux was preferred for its ability to simultaneously process data and display it in real time. This includes creating appropriate sensors, proper modifying circuits and ensuring real time display. The project has a channel for the variable that will be continuously measured and displayed by the device. The variable is electrocardiogram.

For transmission of large amounts of electric power, AC in the overwhelming majority of cases is ... more For transmission of large amounts of electric power, AC in the overwhelming majority of cases is the established as well as the most cost effective option at hand. In cases of long distance transmission, as in interconnection of power systems, care has to be taken for safeguarding of synchronism as well as stable system voltages in the interconnection, particularly for extreme load conditions and in conjunction with system faults. Use of Thyristor Controlled Series Capacitor (TCSC) as Flexible AC Transmission System (FACTS) device brings a number of benefits for the user of the grid, all contributing to an increase of the power transmission capability of new as well as existing transmission lines. These benefits include improvement in system stability, voltage regulation, reactive power balance, load sharing between parallel lines and reduction in transmission losses.

Light trapping in thin-film solar cell to enhance the absorption efficiency using FDTD simulation

Journal of Optics

Recently, plasmonics has been used to trap the light at nanoscale to improve the absorption in so... more Recently, plasmonics has been used to trap the light at nanoscale to improve the absorption in solar cells. In this study, we construct a silicon thin-film solar cell (TFSC) using finite-difference time-domain (FDTD) simulation. The TFSC solar cell was designed with TiO2 anti-reflection layer, aluminum (Al) as a reflective layer, and silicon (Si) as a absorption layer. The silver nanoparticles of 50 nm diameter and 400 nm separation are embedded on absorption layer. Optimizing the location of nanoparticle, light scattering efficiency and near-filled light concentration has been harnessed. The reflective Al layer reflect the light towards upper layer and increases the overall absorption. The proposed structure allows the sunlight to enter into the absorption layer at all directions, breaking the molecular bonding and releasing electrons. We determined the short-circuit current, fill factor, open-circuit voltage, absorption efficiency, and conversion efficiency of our proposed model. The simulation results reveals that, TFSC with embedded nanoparticle array, antireflection coating and reflective layer has higher short-circuit current of 23.98 mA/cm2, higher fill-factor of 0.84 and an efficiency of 12.3%.The proposed TFSC solar cell increases the absorption efficiency by 43.5% and conversion efficiency by 64.66% compared with conventional TFSC. The findings will be helpful to design more efficient and cost effective solar cell utilizing light-trapping mechanism of plasmonic nanoparticle of different size, shape, and geometry.

Design and Development of IoT Based Accident Detection and Emergency Response System

Proceedings of the 2020 5th International Conference on Cloud Computing and Internet of Things

The number of road accidents is increasing at a rapid pace which also affects the death rate that... more The number of road accidents is increasing at a rapid pace which also affects the death rate that is proportional to the number of accidents occurring. This is a serious issue that has unfortunately become somewhat normalized due to how deeply embedded it is in the day-to-day lives of people, especially in developing countries. For any society to make significant progress, it is imperative to utilize our technical skills or otherwise to ensure personal safety before anything else. This includes reducing the time of response to an accident to the minimum, among other things. The development of the Internet of Things (IoT) based accident detection and response system is an attempt towards minimizing the rates of casualty and injuries occurring to both passengers and vehicles due to road accidents. The system is fully automated to be able to send emergency notifications to nearby hospital or fire station and an emergency contact in case of an accident. This is done via a combination of a vehicle device that has to be installed in the vehicle of the consumer and a remote server system that responds to the device accordingly. The motive is to provide the location of the vehicle and measure the severity of the accident so that help can be provided as fast as possible. From the data values collected from the sensors in the vehicle device prototype, we have tested the notification process successfully and also been able to assess the level of accident severity. We believe this system will reduce the response time of emergency responders and in the process improve both the traffic and health system of a society.

International Journal of Nanomedicine, Oct 1, 2018

Background: We have introduced a novel method to quantify the intracellular refractive index (RI)... more Background: We have introduced a novel method to quantify the intracellular refractive index (RI) of living cells and determine the molecular interaction of two interacting molecules using single particle spectroscopy. The advantages of this proposed technique over fluorescence-based imaging techniques is that it does not require any contrasting agent and it does not blink and bleach. Instead, our technique provides a non-destructive, non-invasive, high-resolution imaging of live cells. Methods: To verify our technique, we initially tested our approach for a dielectric medium where gold nanoparticles (AuNPs) were embedded in a polyvinyl alcohol (PVA) matrix, which was then extended to the cellular environment. In the dielectric medium, we identified the single particle and dimer and determined the interparticle distance of AuNPs using confocal laser scattering microscopy. We also determined the single particle RI from dark-field scattering microscopy images, which was confirmed with Mie theory and finite-difference time-domain (FDTD) simulated results. The single particle spectroscopy and microscopy technique was then extended to determine the intracellular RI and biomolecular interaction inside living cells using hyperspectral imaging and dark-field scattering microscopy. Results: The novelty of the paper lies in the demonstration of a direct and accurate method to probe the intracellular RI and molecular interaction focused on single particle analysis whereas previous demonstrations were based on AuNP ensembles. Optically acquired single particle and dimer images was verified by correlated SEM images also optical spectrum with analytical models and FDTD simulations for both the dielectric and cellular environment. We reported the interparticle distance of AuNPs inside HeLa cells and intracellular refractive index, which was also confirmed with Mie Theory and extensive FDTD simulations. Conclusion: Moreover, we believe that our in-depth plasmonic NP-based alternate imaging technique will provide a new insight in monitoring cellular dynamics and tracking the targeted NPs within live cells, enabling us to use plasmonic NPs as an intracellular biosensor.

IEEE Photonics Journal

In this paper, we investigated the plasmon coupling, quantum yield (QY) and effect of tip geometr... more In this paper, we investigated the plasmon coupling, quantum yield (QY) and effect of tip geometry of gold nanoparticles (AuNPs) using finite-difference time-domain (FDTD) simulation. Standalone AuNPs spectra have been obtained using the most reliable electromagnetic theory such as Mie theory for spherical nanoparticle such as gold nanosphere (AuNS) and Mie-Gans theory for ellipsoidal AuNPs such as gold nanorod (AuNR). We reported the scattering cross section for standalone and coupling particle using the modified dielectric constant, where the size effect of small particles and the retardation effect of large particles have been taken into consideration for both the analytical calculation and FDTD simulation. Plasmon coupling effect of AuNS dimer of 80-nm diameter and AuNR dimer (side-by-side geometry) of aspect ratio 3.8 has been investigated using FDTD simulation. We also quantified the QY in terms of cluster to monomer ratio for AuNS and AuNR, which is analogous to the ratio of acceptor and donor chromophore in biological systems. The QY of monomer, dimer, and trimer of 40-nm diameter AuNS has been perceived using FDTD simulation, integrating the whole spectrum over 400-1000 nm wavelength regime. Additionally, effect of tip geometry of AuNPs has been investigated and significant field enhancement due to the variation in shapes such as AuNS, AuNR, gold dumbbell, and gold bipyramid has also been reported. The novelty of the paper lies in the presentation of a systematic study of the plasmon coupling of different sizes and shapes of AuNP, quantification of the QY, and probing the effect of tip geometry for a single material such as AuNP using the FDTD simulation. Moreover, we believe that our in-depth analysis of AuNP laid the foundation to determine the scattering cross-section, QY, and near-field enhancement for more complex structures and geometries of other novel materials. Conclusively, the investigation results demonstrate that plasmonic nanoparticle can be used as a molecular probe for bioimaging, sensing, cell signaling, and biological therapeutic intervention.

ACS applied materials & interfaces, Jan 10, 2017

In this manuscript, we report the refractive-index (RI) modulation of various concentrations of n... more In this manuscript, we report the refractive-index (RI) modulation of various concentrations of nitrogen-doped carbon dots (N@C-dots) embedded in poly(vinyl alcohol) (PVA) polymer. The dispersion and size distribution of N@C-dots embedded within PVA have been investigated using electron microscopy. The RI of PVA-N@C-dots can be enhanced by increasing the doping concentration of highly-fluorescent C-dots (quantum yield 44%). This is demonstrated using ultraviolet-visible (UV-visible), photoluminscence, Raman, and Fourier transform infrared (FTIR) spectroscopy measurements. The Mie-scattering of light on N@C-dots was applied for developing the relationship between RI tuning and absorption cross section of N@C-dots. The extinction cross-section of N@C-dot thin films can be rapidly enhanced by either tuning the RI, or by increasing the concentration of N@C-dots. The developed method can be used as effective RI contrast for various applications such as holography creation and bio-imaging.

Bio-Medical Engineering (BME) has been an active research area for years. BME is the application ... more Bio-Medical Engineering (BME) has been an active research area for years. BME is the application of engineering techniques to the medical fields. It combines the design and problem solving skills of engineering with medical sciences to improve the health care and the quality of individual life. With the proliferation of advanced electronics and applied engineering, the ways to help people specifically patients are changed. Therefore, an advanced design for monitoring a vital sign towards experimentation is presented. The vital signs monitor is essentially a real time device that displays certain received signals from the human body. The projects of this sort under taken so far have used windows to display the output whereas this project aims to generate a real time display of the signals received from the human body using Linux. Linux was preferred for its ability to simultaneously process data and display it in real time. The basic principles and methods are outlined. The major components of the system are shown separately, and are discussed individually. Few electronic devices used for data are depicted and described. The final results show a better performance

The aim of this PhD was to develop a technique to quantify the uptake and aggregation of gold nan... more The aim of this PhD was to develop a technique to quantify the uptake and aggregation of gold nanoparticles (AuNPs) using image correlation spectroscopy (ICS). We proposed a non - destructive microscopic optical method using image correlation spectroscopy (ICS) together with plasmon coupling. The combination of these techniques provides an indication of what is happening within cells, both at the microscopic and macroscopic level. This technique could be used in different biological applications including cancer therapy, drug delivery, disease diagnosis and also for probing membrane protein stoichiometry and dynamics. Although visual resolution itself may not be improved, the ability to ‘see’ inside cells may be enhanced by the use of the methods discovered here.

2010 2nd International Conference on Mechanical and Electronics Engineering, 2010

Utilization of renewable energy resources have been the most important & prospective field to see... more Utilization of renewable energy resources have been the most important & prospective field to seek new energy sources to meet up the increasing demand in power all over the world specially in a developing country like Bangladesh. Among the renewable resources, wind & solar being the most popular ones due to abundant, ease of accessibility and convertibility to the electricity. This paper presents the analysis and design of a hybrid solar-wind system for micro generation for domestic purpose in the rural & remote areas of our country where continuous power supply from central grid has been a great is problem and sometimes for some remote places it's economically not viable at all as far as our country is concerned. We propose such a hybrid system which is expected to run effectively under a microcontroller to utilize the maximum possible solar & wind resources to reduce the demands on national grid for on-grid region as well as to supply power to those places where there is no grid line (i.e. off-grid region).

International Journal of Nanomedicine, 2013

Aqueous solutions of ultra-pure gold nanoparticles have been prepared by methods of femtosecond l... more Aqueous solutions of ultra-pure gold nanoparticles have been prepared by methods of femtosecond laser ablation from a solid target and fragmentation from already formed colloids. Despite the absence of protecting ligands, the solutions could be (1) fairly stable and poly size-dispersed; or (2) very stable and monodispersed, for the two fabrication modalities, respectively. Fluorescence quenching behavior and its intricacies were revealed by fluorescence lifetime imaging microscopy in rhodamine 6G water solution. We show that surface-enhanced Raman scattering of rhodamine 6G on gold nanoparticles can be detected with high fidelity down to micromolar concentrations using the nanoparticles. Application potential of pure gold nanoparticles with polydispersed and nearly monodispersed size distributions are discussed.

A comparative analysis between the Step Index fiber and Polarization Maintaining fiber on the basis of their modal solutions

2010 International Conference on Electronics and Information Engineering, 2010

Abstract This paper reviews a modal solution of the single mode Step Index fiber and Polarization... more Abstract This paper reviews a modal solution of the single mode Step Index fiber and Polarization Maintaining fiber based on the analysis and simulation with FEM lab which reflects a significant way of propagating signals with less power consumptions as the ...

International Journal of Engineering and Technology, 2011

Energy is one of the main concerns for the growing future of any nation. Energy is by far the lar... more Energy is one of the main concerns for the growing future of any nation. Energy is by far the largest merchandise in the world and an enormous amount of energy is extracted, distributed, converted and consumed in our global society daily. The per capita energy consumption of Bangladesh is one of the lowest amongst the sub continent. Despite only 32% population has access to the National grid, The Government of Bangladesh a noble vision to provide electricity for all by the year 2020.Target of meeting 5% of total electricity demand from RE by 2010 and 10% by the year 2020 .In crisis conditions energy usage should be appropriate and meticulous. Our technology for energy harvest, conversion and efficient application is still lacking behind with that of developed world. We should give emphasis for the development of indigenous technology. Bangladesh is situated between 20.30 and 26.38 degrees north latitude and 88.04 and 92.44 degrees east longitude, which is an ideal location for solar energy utilization. Daily solar radiation varies between 4 and 6.5 kWh/m2.In this regard, solar dryer for domestic as well industrial usage could be an effective alternative of saving conventional energy. Utilization of solar thermal energy through solar dryer is relatively in a nascent state in our country. The objective of this paper is the design & performance analysis of different types of solar dryer & its prospect in Bangladesh.

In this paper we demonstrate multilayer fabrication of plasmonic gold nanorod arrays using electr... more In this paper we demonstrate multilayer fabrication of plasmonic gold nanorod arrays using electron-beam lithography (EBL), and show that this structure could be used for multilayered optical storage media capable of continuous-wave (cw) laser readout. The gold nanorods fabricated using the EBL method are aligned perfectly and homogeneous in size and shape, allowing the polarization response of surface plasmon resonance (SPR) to be observed through ensemble array. This property in turn permits polarization detuned SPR readout possible and other manipulations such as progressively twisted arrays through the multilayers to make cw readout possible through deeper layers without too much extinction loss. The layered gold nanorod arrays are separated by thick spacer layer to enable the optical resolving of individual layers. Using this method, we demonstrated four-fold reduction in extinction loss for cw readout in three-layer structure. The current technique of multilayer fabrication and readout can be useful in 3-dimensional fabrication of plasmonic circuits and structures.