Simple Microscope Research Articles

Role of Microscopy in Forensic Science Research and Investigation

The present review article deals with the utility of microscope in a forensic science and its utility in research and investigation. The review article tries to explain the basic of microscopes ranging from a simple microscope to electron microscope. It further explains the utility of microscopes in a multitude of areas that could ease investigation and research in a forensic science laboratory.

The Technology of the Near-Field Interference Microwave Sensing

We describe the operation of a simple near-field interference microwave microscope. The microscope contains two identical probes which are connected to the ends of segments of the coaxial transmission line. The probes are constructed from an open-ended conical coaxial line and are excited by applied microwave voltage in the frequency range of 0.6 – 7.0 GHz. The computer simulation of the field distribution near the aperture of a separate probe was performed. The test objects are placed in the gap between the probes apertures. The main attention was concentrated on motor fuels to detect other impurities. In particular, diesel fuel was studied with impurities in the form of kerosene and synthetic motor oil in different proportions. It is shown that the microscope can reliably detect these impurities even if their content is relatively small. It was also demonstrated that the microscope can be used for determination of the alcohol quality and spirit-based solutions.

Frequency domain image analysis for the characterization of porous products

Abstract Many pharmaceutical products are obtained via freeze-drying of liquid solutions to obtain stable long lasting preparations. The freeze-dry process produces porous cakes whose structure strongly depends on the freezing phase, so that monitoring and optimizing this phase can help both reducing the product cost and insuring its constant quality. Nowadays the optimization is usually performed by determining the cake mass transfer coefficient via a costly process in pilot plants, while the quality is assured only by controlling the process conditions. This paper describes an alternative way of approximately estimating the mass transfer coefficient, which is based on the observation of the product structure by a simple electron microscope followed by a frequency domain imaging process. While the process has been designed and characterized specifically for pharmaceutical products, the proposed approach can be used in several other fields where the characteristics of porous material have to be monitored.

Design and first applications of a flexible Raman micro-spectroscopic system for biological imaging

Typical commercial Raman micro-spectroscopic systems do not offer much flexibility to the end user, thus limiting potential research applications. We present a design of a simple, highly flexible and portable confocal Raman microscope with a detailed list of parts. The system can perform spectral acquisition in different modes: single-point spectroscopy, hyperspectral point mapping or hyperspectral line mapping. Moreover, the microscope can be easily converted between inverted and upright configurations, which can be beneficial for specific situations. Fiber coupling enables to connect various lasers for excitation and spectrometer/CCD combinations for signal detection. The performance of the instrument is demonstrated via Raman spectroscopy at 785 nm excitation wavelength, single point mapping of pancreatic cancer cells placed onto a quartz substrate and line mapping of polystyrene beads.

Programmable aperture microscopy: A computational method for multi-modal phase contrast and light field imaging

We demonstrate a simple and cost-effective programmable aperture microscope to realize multi-modal computational imaging by integrating a programmable liquid crystal display (LCD) into a conventional wide-field microscope. The LCD selectively modulates the light distribution at the rear aperture of the microscope objective, allowing numerous imaging modalities, such as bright field, dark field, differential phase contrast, quantitative phase imaging, multi-perspective imaging, and full resolution light field imaging to be achieved and switched rapidly in the same setup, without requiring specialized hardwares and any moving parts. We experimentally demonstrate the success of our method by imaging unstained cheek cells, profiling microlens array, and changing perspective views of thick biological specimens. The post-exposure refocusing of a butterfly mouthpart and RFP-labeled dicot stem cross-section is also presented to demonstrate the full resolution light field imaging capability of our system for both translucent and fluorescent specimens.

A Comparative Study Between Smartphone-Based Microscopy and Conventional Light Microscopy in 1021 Dermatopathology Specimens

ContextThe incorporation of high-resolution cameras into smartphones has allowed for a variety of medical applications including the use of lens attachments that provide telescopic, macroscopic, and dermatoscopic data, but the feasibility and performance characteristics of such a platform for use in dermatopathology have not been described.ObjectiveTo determine the diagnostic performance of a smartphone microscope compared to traditional light microscopy in dermatopathology specimens.DesignA simple smartphone microscope constructed with a 3-mm ball lens was used to prospectively evaluate 1021 consecutive dermatopathology cases in a blinded fashion. Referred, consecutive specimens from the community were evaluated at a single university hospital. The performance characteristics of the smartphone platform were calculated by using conventional light microscopy as the gold standard. The sensitivity and specificity for the diagnosis of melanoma, nonmelanoma skin cancers, and other miscellaneous conditions by the phone microscopy platform, as compared with traditional light microscopy, were calculated.ResultsFor basal cell carcinoma (n = 136), the sensitivity and specificity of smartphone microscopy were 95.6% and 98.1%, respectively. The sensitivity and specificity for squamous cell carcinoma (n = 94) were 89.4% and 97.3%, respectively. The lowest sensitivity was found in melanoma (n = 15) at 60%, although the specificity was high at 99.1%. The accuracy of diagnosis of inflammatory conditions and other neoplasms was variable.ConclusionsMobile phone–based microscopy has excellent performance characteristics for the inexpensive diagnosis of nonmelanoma skin cancers in a setting where a traditional microscope is not available.

Development and Evaluation of a Tablet with a Simple Microscope for Observation of Organisms in High Schools

Development and Evaluation of a Tablet with a Simple Microscope for Observation of Organisms in High Schools

Optogenetic spatial and temporal control of cortical circuits on a columnar scale.

Many circuits in the mammalian brain are organized in a topographic or columnar manner. These circuits could be activated-in ways that reveal circuit function or restore function after disease-by an artificial stimulation system that is capable of independently driving local groups of neurons. Here we present a simple custom microscope called ProjectorScope 1 that incorporates off-the-shelf parts and a liquid crystal display (LCD) projector to stimulate surface brain regions that express channelrhodopsin-2 (ChR2). In principle, local optogenetic stimulation of the brain surface with optical projection systems might not produce local activation of a highly interconnected network like the cortex, because of potential stimulation of axons of passage or extended dendritic trees. However, here we demonstrate that the combination of virally mediated ChR2 expression levels and the light intensity of ProjectorScope 1 is capable of producing local spatial activation with a resolution of ∼200-300 μm. We use the system to examine the role of cortical activity in the experience-dependent emergence of motion selectivity in immature ferret visual cortex. We find that optogenetic cortical activation alone-without visual stimulation-is sufficient to produce increases in motion selectivity, suggesting the presence of a sharpening mechanism that does not require precise spatiotemporal activation of the visual system. These results demonstrate that optogenetic stimulation can sculpt the developing brain.

A Student-Built Scanning Tunneling Microscope

Many introductory and nanotechnology textbooks discuss the operation of various microscopes including atomic force (AFM), scanning tunneling (STM), and scanning electron microscopes (SEM). In a nanotechnology laboratory class, students frequently utilize microscopes to obtain data without a thought about the detailed operation of the tool itself. I wanted to give my students a deeper appreciation for the physics by having them build a simple scanning tunneling microscope. Initially, 15 hours of an upper-division laboratory class were devoted to building and operating the STM. As the build process was refined, the time commitment for this project has shrunk to nine hours. Using the method described in this paper, the project is now simple enough that it can be built and operated by students in the introductory class.

In situ label-free static cytometry by monitoring spatiotemporal fluctuations of image gray values.

Spatiotemporal fluctuation of homogeneity and randomness of gray values within an image was explored and utilized as a label-free means for cell examination. This was done by utilizing a user-friendly combination of simple bright field microscope and Cytocapture dish, wherein cells are individually held, each within a picoliter optical chamber, forming an array of cells to be repeatedly measured over time and biomanipulated in situ at single-cell resolution. First, the measured gray level information entropy (GLIE) was used and, based on the fact that living cells are not in a state of thermodynamic equilibrium but rather in a metastable state, two fluctuation-sensitive measures were proposed and examined: ASDE—the spatial average of temporal standard deviation (SD) of GLIE, and AA—the average time autocorrelation of GLIE. System performance was validated on cell-free solutions. This was followed by examining the performance of the measures AGLIE, ASDE, and AA to distinguish among individual live-still, dead and live cells from various cell lines, as well as between cells which were and were not induced to differentiate. Results, which were obtained on four types of cells, indicate advantages of the proposed measures which are believed to be significant additions to the microscope-based probe-free toolbox.

Design of a simple, low-cost, computer-controlled, dual-beam optical tweezer system

We present the design of a simple optical tweezer system. Our system modifies a simple compound microscope to provide one stationary and one steerable trap. Vertical integration of the optical components results in a device with a small footprint that is both compact and portable. Motorized mounting systems are constructed to achieve precise trap motion in three dimensions. Control and image acquisition are performed via an intuitive computer interface. Common and readily obtainable components were incorporated into the apparatus to reduce cost and complexity. The system was used to successfully trap and manipulate yeast cells, and by tuning the laser power, trapping can easily be extended to a wide range of biological and dielectric samples.

Fabricating in-plane transistor and memory using atomic force microscope lithography towards graphene system on chip

Recently, various electronic components including transistor, barristor, memory, and transparent electrode were implemented using graphene. While integrated circuits were demonstrated by combining graphene transistors and passive components, system on chip (SoC) platform, state-of-the-art semiconductor technology, by combining transistors and memories on the same chip, has not yet been demonstrated. The main obstacle of the realization of SoC is the complexity of fabrication processes originated from the process differences between the transistors and the memories. In this study, using simple and clean atomic force microscope lithography, we fabricated both the switching devices and the memories by forming very thin graphene oxide (GO) barriers in mono-layer graphene at the controlled oxidation voltages. Formed with 7 V and 9 V, the lateral graphene/GO/graphene junction devices exhibit switching of Fowler-Nordheim tunneling current and resistive memory behavior, respectively. The combination of high on/off current ratio (∼1000) of the switching device and nonvolatility of the memory device fabricated by the same process demonstrates the possibility of graphene SoC platform.

Simple concept for a wide-field lensless digital holographic microscope using a laser diode

Abstract Wide-field, lensless digital holographic microscopy is a new microscopic imaging technique for telemedicine and for resource limited setting [1]. In this contribution we propose a very simple wide-field lensless digital holographic microscope using a laser diode. It is based on in-line digital holography which is capable to provide amplitude and phase images of a sample resulting from numerical reconstruction. The numerical reconstruction consists of the angular spectrum propagation method together with a phase retrieval algorithm. Amplitude and phase images of the sample with a resolution of ∽2 µm and with ∽24 mm2 field of view are obtained. We evaluate our setup by imaging first the 1951 USAF resolution test chart to verify the resolution. Second, we record holograms of blood smear and diatoms. The individual specimen can be easily identified after the numerical reconstruction. Our system is a very simple, compact and low-cost possibility of realizing a microscope capable of imaging biological samples. The availability of the phase provide topographic information of the sample extending the application of this system to be not only for biological sample but also for transparent microstructure. It is suitable for fault detection, shape and roughness measurements of these structures.

Susceptibility to bunch stem necrosis in grapes: A breeding screen

A breeding screen has been developed with which it is possible to predict the resistance of newbred grapevine varieties to bunch stem necrosis. The screen is based on a 5-year study of 17 commercial varieties in which it was noted that in those which are sensitive to the disorder, xylem development is relatively reduced just distal to each branch point in the peduncle so as to form a short ''bottleneck'' (DURING and LANG 1993). The procedure advocated, offers a probabilistic assessment of susceptibility to the disorder, calculated from simple light microscope measurements on a relatively small amount of material.

Fourier Plane Imaging Microscopy for Detection of Plasmonic Crystals with Periods beyond the Optical Diffraction Limit

Using a simple optical microscope, composed of a plasmonic ultrathin condenser, an objective lens, and a camera, we show that the captured Fourier plane images can provide more information than the real plane images that would be obtained from the corresponding compound microscope. Using this simple Fourier plane imaging approach, we demonstrate that reconstructed non-scanning images of plasmonic crystals with lateral resolution beyond the optical diffraction limit can be obtained.

Capturing tissue repair in zebrafish larvae with time-lapse brightfield stereomicroscopy.

The zebrafish larval tail fin is ideal for studying tissue regeneration due to the simple architecture of the larval fin-fold, which comprises of two layers of skin that enclose undifferentiated mesenchyme, and because the larval tail fin regenerates rapidly within 2-3 days. Using this system, we demonstrate a method for capturing the repair dynamics of the amputated tail fin with time-lapse video brightfield stereomicroscopy. We demonstrate that fin amputation triggers a contraction of the amputation wound and extrusion of cells around the wound margin, leading to their subsequent clearance. Fin regeneration proceeds from proximal to distal direction after a short delay. In addition, developmental growth of the larva can be observed during all stages. The presented method provides an opportunity for observing and analyzing whole tissue-scale behaviors such as fin development and growth in a simple microscope setting, which is easily adaptable to any stereomicroscope with time-lapse capabilities.

Capturing Tissue Repair in Zebrafish Larvae with Time-lapse Brightfield Stereomicroscopy

The zebrafish larval tail fin is ideal for studying tissue regeneration due to the simple architecture of the larval fin-fold, which comprises of two layers of skin that enclose undifferentiated mesenchyme, and because the larval tail fin regenerates rapidly within 2-3 days. Using this system, we demonstrate a method for capturing the repair dynamics of the amputated tail fin with time-lapse video brightfield stereomicroscopy. We demonstrate that fin amputation triggers a contraction of the amputation wound and extrusion of cells around the wound margin, leading to their subsequent clearance. Fin regeneration proceeds from proximal to distal direction after a short delay. In addition, developmental growth of the larva can be observed during all stages. The presented method provides an opportunity for observing and analyzing whole tissue-scale behaviors such as fin development and growth in a simple microscope setting, which is easily adaptable to any stereomicroscope with time-lapse capabilities.

Most clinical laboratory testing in Kampala occurs in high-volume, high-quality laboratories or low-volume, low-quality laboratories. A tale of two cities.

To describe key characteristics (laboratory quality, test volumes, and complexity) of clinical laboratories in Kampala, Uganda (population ~1.7 million). Cross-sectional survey using a standard questionnaire to document laboratory type and quality, as well as test menus and volumes. Quality was based on the World Health Organization-Africa Region checklist. Of the 954 laboratories identified (a density of one laboratory per 1,781 persons), 779 (82%) performed only simple kit tests or light microscope examinations. The 95% (907/954) of laboratories for whom volumes were obtained performed an average aggregate of 13,189 tests daily, for a test utilization rate of around 2 tests per individual per year. Laboratories could be segregated into eight groups based on quality, test volume, and complexity. However, 90% of the testing was performed by just two groups: (1) low-volume (≤100 tests daily), low-quality laboratories performing simple tests or (2) high-volume (>100 tests daily), high-quality laboratories. Each of these two groups did 45% of the daily testing volume (90% combined). Clinical laboratory density in Kampala (1/1,781 persons) is high, approaching that in the United States (1/1,347 persons). Low-volume/low-quality and high-volume/high-quality laboratories do 90% of the daily aggregate testing. Quality improvement (QI) schemes for Africa must be appropriate to low-volume laboratories as well as to the large laboratories that have been the focus of previous QI efforts.

Design and Construction of a Confocal Laser Scanning Microscope for Biomolecular Imaging

Confocal fluorescence microscopy has established itself now as an indispensable tool for biomedical and biomolecular research. However, the rigid design and high cost of the commercially available confocal microscopes have limited its wider usage. Here we report on the development of a confocal laser scanning microscope and demonstrate the three-dimensional sectioning capability of the microscope. The design is versatile and cost-effective, and can be constructed using components normally available in an optics laboratory with minimum amount of additional expenditure. Detailed description of the design and alignment procedure is given so that this note can serve as a primer for construction of a simple confocal microscope.

Dirac-fermion-induced parity mixing in superconducting topological insulators

We self-consistently study surface states of superconducting topological insulators. We clarify that, if a topologically trivial bulk $s$-wave pairing symmetry is realized, parity mixing of the pair potential near the surface is anomalously enhanced by surface Dirac fermions, opening an additional surface gap larger than the bulk one. In contrast to classical $s$-wave superconductors, the resulting surface density of state hosts an extra coherent peak at the induced gap besides a conventional peak at the bulk gap. We also find that no such extra peak appears for odd-parity superconductors with a cylindrical Fermi surface. Our calculation suggests that the simple U-shaped scanning tunneling microscope spectrum in ${\mathrm{Cu}}_{x}{\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$ does not originate from $s$-wave superconductivity, but can be explained by odd-parity superconductivity with a cylindrical Fermi surface.