Dark Field Digital Holographic Microscopy Based on Two-lens 360-degree Oblique Illumination

Xiuying Zhang,Yingchun Zhao,Caojin Yuan,Shaotong Feng,Lin Wang 한국광학회 2020 Current Optics and Photonics Vol.4 No.3

In this paper we propose a dark-field digital holographic microscopy system based on 360-degree oblique illumination. This setup is constructed without using a dark-field objective. The principle of 360-degree oblique illumination of vortex beam and dark-field digital holographic microscopy are introduced theoretically and experimentally. By analyzing the reconstructed image of a dark-field digital hologram of a USAF 1951 target, it is proved that the imaging resolution can be improved by this method. And also, comparison and analysis are made on the reconstructed image of a bright-dark field digital hologram of a pumpkin stem slice, the result shows that the imaging contrast is also enhanced with this method, and it is effective for dark-field digital holographic microscopy imaging of large transparent biological samples.

Real-time Monitoring of Colloidal Nanoparticles using Light Sheet Dark-field Microscopy Combined with Microfluidic Concentration Gradient Generator (μFCGG-LSDFM)

Choe, Hyeokmin,Nho, Hyun Woo,Park, Jonghoon,Kim, Jin Bae,Yoon, Tae Hyun Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.2

For real-time monitoring of colloidal nanoparticles (NPs) in aqueous media, a light sheet type dark-field microscopy system combined with a microfluidic concentration gradient generator (${\mu}FCGG$-LSDFM) was developed. Various concentrations of colloidal Au NPs were simultaneously generated with the iFCGG and characterized with the LSDFM setup. The number concentrations and hydrodynamic size distributions were measured via particle counting and tracking analysis (PCA and PTA, respectively) approaches. For the 30 nm Au NPs used in this study, the lower detection limit of the LSDFM setup was 3.6 ng/mL, which is about 400 times better than that of optical density measurements under the same ${\mu}FCGG$ system. Additionally, the hydrodynamic diameter distribution of Au NPs was estimated as $39.7{\pm}12.2nm$ with the PTA approach, which agrees well with DLS measurement as well as the manufacturer's specification. We propose this ${\mu}FCGG$-LSDFM setup with features of automatic generation of NP concentration gradient and real-time monitoring of their physicochemical characteristics (e.g., number concentration, and hydrodynamic size distribution) as an important component of future high-throughput screening or high-content analysis platforms of nanotoxicity.

Supersensitive single-particle plasmonic scattering-based cancer antigen 125 nanoimmunosensor by enhanced dark-field microscopy with dual-detection mode

Ju, Soyeong,Chakkarapani, Suresh Kumar,Lee, Seungah,Kang, Seong Ho Elsevier 2017 Sensors and actuators. B Chemical Vol.245 No.-

<P><B>Abstract</B></P> <P>A supersensitive nanoimmunosensor of cancer antigen 125 (CA125), which is a stage marker of several types of cancers, was developed based on characterization of single-particle plasmonic scattering by wavelength-dependent enhanced dark-field microscopy with dual-detection mode (EDFM-DM). Considering the optical properties of gold and silver nanoparticles (AuNPs/AgNPs), 40-nm AgNP was selected as an optimal fluorescence-free probe. CA125 was analyzed using the wavelength-dependent plasmonic scattering intensity of 40-nm AgNP-labeled CA125 immunoreacted on gold nanodots under the dual-detection mode. A color digital camera and an electron multiplying charge-coupled device camera were used for qualitative and quantitative analysis, respectively, based on the dark-field scattering images. Under optimal conditions, the developed immunosensor exhibited a lower detection limit of 4μU/mL (<I>S</I>/<I>N</I> =3) with a wide dynamic detection range of 4μU/mL-80U/mL (<I>R</I> =0.9935), which was a 100–375,000-fold lower detection limit with a 100–100,000-fold wider dynamic range than previous methods. In addition, recovery was greater than 98% with the spiking of standard CA125 in human serum samples. This method may be an excellent nanoimmunoassay platform for supersensitive detection at a wide dynamic detection range, supporting the earliest-stage detection of various disease-related protein molecules at the single-molecule level.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Supersensitive CA125 nanoimmunosensor with LOD (4μU/mL). </LI> <LI> Wavelength-dependent single-particle plasmonic scattering-based detection. </LI> <LI> 5-nm NP detection by EDF microscopy with dual-detection mode. </LI> <LI> 100–375,000 times lower LOD than previous methods. </LI> <LI> 100–100,000 times wider dynamic range than previous methods. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>A novel wavelength-dependent enhanced dark-field microscopy with dual-detection mode provides the supersensitive nanoimmunosensor of CA125 at wide dynamic detection range.▪</P>

Dark-field Transmission Electron Microscopy Imaging Technique to Visualize the Local Structure of Two-dimensional Material; Graphene

Na, Min Young,Lee, Seung-Mo,Kim, Do Hyang,Chang, Hye Jung Korean Society of Microscopy 2015 Applied microscopy Vol.45 No.1

Dark field (DF) transmission electron microscopy image has become a popular characterization method for two-dimensional material, graphene, since it can visualize grain structure and multilayer islands, and further provide structural information such as crystal orientation relations, defects, etc. unlike other imaging tools. Here we present microstructure of graphene, particularly, using DF imaging. High-angle grain boundary formation wass observed in heat-treated chemical vapor deposition-grown graphene on the Si substrate using patch-quilted DF imaging processing, which is supposed to occur by strain around multilayer islands. Upon the crystal orientation between layers the multilayer islands were categorized into the oriented one and the twisted one, and their local structure were compared. In addition information from each diffraction spot in selected area diffraction pattern was summarized.

Transmission electron microscopy study of microstructural properties and dislocation characterization in the GaN film grown on the cone-shaped patterned Al₂O₃ substrate

Park, Jung Sik,Yang, Jun-Mo,Park, Kyung Jin,Park, Yun Chang,Yoo, Jung Ho,Jeong, Chil Seong,Park, Jucheol,He, Yinsheng,Shin, Keesam Oxford University Press 2014 Microscopy Vol.63 No.1

<P>Growing a GaN film on a patterned Al<SUB>2</SUB>O<SUB>3</SUB> substrate is one of the methods of reducing threading dislocations (TDs), which can significantly deteriorate the performance of GaN-based LEDs. In this study, the microstructural details of the GaN film grown on a cone-shaped patterned Al<SUB>2</SUB>O<SUB>3</SUB> substrate were investigated using high-resolution transmission electron microscopy and weak-beam dark-field techniques. Various defects such as misfit dislocations (MDs), recrystallized GaN (R-GaN) islands and nano-voids were observed on the patterned Al<SUB>2</SUB>O<SUB>3</SUB> surfaces, i.e. the flat surface (FS), the inclined surface (IS) and the top surface (TS), respectively. Especially, the crystallographic orientation of R-GaN between the GaN film and the inclined Al<SUB>2</SUB>O<SUB>3</SUB> substrate was identified as [Formula], [Formula]. In addition, a rotation by 9° between [Formula] and [Formula] and between [Formula] and [Formula] was found to reduce the lattice mismatch between the GaN film and the Al<SUB>2</SUB>O<SUB>3</SUB> substrate. Many TDs in the GaN film were observed on the FS and TS of Al<SUB>2</SUB>O<SUB>3</SUB>. However, few TDs were observed on the IS. Most of the TDs generated from the FS of Al<SUB>2</SUB>O<SUB>3</SUB> were bent to the inclined facet rather than propagating to the GaN surface, resulting in a reduction in the dislocation density. Most of the TDs generated from the TS of Al<SUB>2</SUB>O<SUB>3</SUB> were characterized as edge dislocations.</P>

2D strain measurement in sub-10 nm SiGe layer with dark-field electron holography

Van Vuong Hoang,조영지,유정호,양준모,최성하,정우덕,최용호,홍순구 한국물리학회 2015 Current Applied Physics Vol.15 No.11

In this paper, we carried out the two-dimensional (2D) strain measurement in sub-10 nm SiGe layer; images were obtained by dark-field electron holography (DFEH). This technique is based on transmission electron microscopy (TEM), in which dark-field holograms were obtained from a (400) diffraction spot. The measured results were compared to the X-ray diffraction (XRD) results in terms of the strain value and the depth of strain distribution in a very thin SiGe layer. Subsequently, we were able to successfully analyze the 2D strain maps along the [100] growth direction of the nanoscale SiGe region. The strain was measured and found to be in the range of 1.8-2.4%. The strain precision was estimated at 2.5 × 10-3. As a result, the DFEH technique is truly useful for measuring 2D strain maps in very thin SiGe layers with nanometer resolution and high precision.

2D strain measurement in sub-10 nm SiGe layer with dark-field electron holography

Hoang, V.V.,Cho, Y.J.,Yoo, J.H.,Yang, J.M.,Choi, S.,Jung, W.,Choi, Y.H.,Hong, S.K. Elsevier 2015 CURRENT APPLIED PHYSICS Vol.15 No.11

In this paper, we carried out the two-dimensional (2D) strain measurement in sub-10 nm SiGe layer; images were obtained by dark-field electron holography (DFEH). This technique is based on transmission electron microscopy (TEM), in which dark-field holograms were obtained from a (400) diffraction spot. The measured results were compared to the X-ray diffraction (XRD) results in terms of the strain value and the depth of strain distribution in a very thin SiGe layer. Subsequently, we were able to successfully analyze the 2D strain maps along the [100] growth direction of the nanoscale SiGe region. The strain was measured and found to be in the range of 1.8-2.4%. The strain precision was estimated at 2.5 x 10<SUP>-3</SUP>. As a result, the DFEH technique is truly useful for measuring 2D strain maps in very thin SiGe layers with nanometer resolution and high precision.

Real-time Monitoring of Colloidal Nanoparticles using Light Sheet Dark-field Microscopy Combined with Microfluidic Concentration Gradient Generator (μFCGG-LSDFM)

Hyeokmin Choe,Hyun Woo Nho,Jonghoon Park,Jin Bae Kim,Tae Hyun Yoon 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.2

For real-time monitoring of colloidal nanoparticles (NPs) in aqueous media, a light sheet type dark-field microscopy system combined with a microfluidic concentration gradient generator (㎌CGG-LSDFM) was developed. Various concentrations of colloidal Au NPs were simultaneously generated with the ìFCGG and characterized with the LSDFM setup. The number concentrations and hydrodynamic size distributions were measured via particle counting and tracking analysis (PCA and PTA, respectively) approaches. For the 30 nm Au NPs used in this study, the lower detection limit of the LSDFM setup was 3.6 ng/mL, which is about 400 times better than that of optical density measurements under the same ㎌CGG system. Additionally, the hydrodynamic diameter distribution of Au NPs was estimated as 39.7 ± 12.2 nm with the PTA approach, which agrees well with DLS measurement as well as the manufacturer’s specification. We propose this ㎌CGG-LSDFM setup with features of automatic generation of NP concentration gradient and real-time monitoring of their physicochemical characteristics (e.g., number concentration, and hydrodynamic size distribution) as an important component of future high-throughput screening or high-content analysis platforms of nanotoxicity.

Elucidating the contribution of dipole resonance mode to polarization-dependent optical properties in single triangular gold nanoplates

Lee, Junho,Ha, Ji Won Elsevier 2018 Chemical physics letters Vol.713 No.-

<P><B>Abstract</B></P> <P>We synthesized triangular gold nanoplates (AuNPs) through a one-pot seedless growth method and characterized their optical properties under dark-field (DF) microscopy at the single particle level. We experimentally demonstrated that the dipole resonance is not completely separated from the quadrupole resonance for single AuNPs with an aspect ratio of ∼5. We further used a defocused orientation and position imaging technique to visualize the spatial scattering field distributions from dipole and quadrupole modes. Their optical properties were mainly dominated by the dipole resonance, which resulted in the polarization-dependent, periodic DF defocused images and intensities of single AuNPs.</P> <P><B>Highlight</B></P> <P> <UL> <LI> We characterized optical properties of single triangular gold nanoplate under DF microscopy. </LI> <LI> The optical properties are mainly dominated by the dipole resonance in single Au nanoplate with aspect ratio of 5. </LI> <LI> We observed the polarization-dependent, periodic DF defocused images and intensities of single Au nanoplates. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Visualizing Point Defects in Transition-Metal Dichalcogenides Using Optical Microscopy

Jeong, Hye Yun,Lee, Si Young,Ly, Thuc Hue,Han, Gang Hee,Kim, Hyun,Nam, Honggi,Jiong, Zhao,Shin, Bong Gyu,Yun, Seok Joon,Kim, Jaesu,Kim, Un Jeong,Hwang, Sungwoo,Lee, Young Hee American Chemical Society 2016 ACS NANO Vol.10 No.1

<P>While transmission electron microscopy and scanning tunneling microscopy reveal atomic structures of point defect and grain boundary in monolayer transition metal dichalcogenides (TMDs), information on point defect distribution in macroscale is still not available. Herein, we visualize the point defect distribution of monolayer TMDs using dark-field optical microscopy. This was realized by anchoring silver nanoparticles on defect sites of MoS2 under light illumination. The optical images clearly revealed that the point defect distribution varies with light power and exposure time. The number of silver nanoparticles increased initially and reached a plateau in response to light power or exposure time. The size of silver nanoparticles was a few hundred nanometers in the plateau region as observed using optical microscopy. The measured defect density in macroscale was similar to 2 x 10(10) cm(-2), slightly lower than the observed value (4 x 10(11) cm(-2)) from scanning tunneling microscopy.</P>