Handheld Microscope Research Articles

A comparison of current analytical methods for detecting particulate matter and micro/nanoplastics

Micro- and nanoplastics (MNPs) are increasingly found in all realms of the world, including water and soil. Now, there is growing concern over this type of pollution in the air. Many well-established techniques exist for detecting particulate matter (PM) in the air. They are low-cost and handheld, and some of them even allow direct detection from the air. While various MNP detection methods have been demonstrated, airborne MNP detection methods depend on expensive laboratory instruments. This review paper examines the current analytic methods used to identify PM and MNP and discusses their similarities and differences. PM can be detected directly from the air primarily via light scattering, while direct air detection of MNP has not been demonstrated. Sampling steps allow both PM and MNP to be detected from the air. Since PM detection does not require the type identification of materials, mass detection has been utilized, including gravimetric and microbalance methods. Simple optical detection based on absorbance or reflectance and electrical current measurements have also been used for PM detection. However, MNP detection does require type identification, including plastic vs non-plastic or the type of plastic, requiring more sophisticated methods, including spectroscopic and thermal analyses. Microscopic identification has been utilized for both PM and MNP detection since it can identify the size, morphology, autofluorescence, and spectroscopic properties. Machine learning algorithms can also analyze the microscopic images and spectra to identify the type of PM and MNP. While microscopic identification previously required a bulky benchtop microscope, a portable or even handheld microscope has become available, allowing it to detect MNPs in a portable, low-cost manner.

Assessment of Nailfold Capillaroscopy Findings in Pregnant Women having Preeclampsia: A Research Protocol

Introduction: Pregnancy causes significant vascular and cutaneous changes in a woman’s body. Preeclampsia is one of the life-threatening conditions associated with high blood pressure and proteinuria after the 20th week of pregnancy. It can cause placental hypoperfusion and placental insufficiency, leading to foetal defects or, in severe cases, foetal loss, which can be prevented by early diagnosis and treatment. There are many ways to observe and study the microcirculation non invasively the safest and most accessible method is nailfold capillaroscopy. Nail-fold Video Capillaroscopy (NVC) is a handheld digital microscope used to observe the microcirculation at the nailfold of the hands. Thus, comparing the capillary status with healthy subjects will help establish an early diagnosis and manage cases to prevent further complications in the mother and newborn. Need of the Study: The pathophysiology states that preeclampsia is related to systemic endothelial dysfunction, causing the release of Tumour Necrosis Factor (TNF) alpha, a proinflammatory mediator, leading to hypoxia of the placenta and the loss of endothelial cell-lined capillaries. Thus, there is a need to find if there is an established correlation in association of decreased Capillary Density (CD) in individuals with preeclampsia. Although evidence supporting a link between decreased CD and preeclampsia is limited, timely assessment and prevention are crucial. Nailfold capillaroscopy, an accessible and non invasive imaging method, holds promising calibre for understanding microvascular changes in preeclampsia. This could facilitate post-conception monitoring and early interventions to identify and address circulatory issues in affected women with preeclampsia. Aim: To study and compare the nailfold capillary changes in women diagnosed with preeclampsia and women having normal and uneventful pregnancies. Materials and Methods: A comparative cross-sectional study will be done in the Outpatient Department (OPD) and Inpatient Department (IPD) of Obstetrics and Gynaecology and the Outpatient Department of Dermatology at AVBRH Sawangi Meghe, Wardha, Maharashtra, India, from March 2023 to March 2025. A total of 150 pregnant women will be considered in the study, with 75 women being normal pregnant women (controls) and 75 pregnant women diagnosed with preeclampsia (cases). In order to confirm the gestational age of the patients, fundal height and abdominal circumference measurements will be taken. Demographic data, Basal Metabolic Index (BMI), weight gain during pregnancy, laboratory reports including Complete Blood Count (CBC), coagulation profile (Prothrombin Time, International Normalised Ratio, Activated Partial Thromboplastin Time), liver function tests, kidney function tests, urine examinations, and serial ultrasonography reports available for the patients will be noted. Pre-examination blood pressure will be recorded and compared with the baseline to confirm the status of preeclampsia after obtaining written consent from the patients. Nailfold capillaroscopy will be performed using a (Dinolite -AF4115ZT) dermoscope equipped with a 200X magnification, high-resolution lens in a non polarised light setting with oil immersion as a fluid coupling. The observations will be used to interpret the results of the study. Results will be calculated for finding differences between the two comparative groups of cases and controls at a p-value of ≤0.05.

Handheld cross-polarized microscope for imaging individual pigmented cells in human skin in vivo.

We present the development of a simple, handheld cross-polarized microscope (CPM) and demonstration of imaging individual pigmented cells in human skin in vivo. In the CPM device, the cross-polarized detection approach is used to reduce the specular reflection from the skin surface and preferentially detect multiply-scattered light. The multiply-scattered light works as back illumination from within the tissue towards the skin surface, and superficial pigment such as intraepidermal melanin absorbs some spectral bands of the multiply-scattered light and cast colored shadows. Since the light that interacted with the superficial pigment only needs to travel a short distance before it exits the skin surface, microscopic details of the pigment can be preserved. The CPM device uses a water-immersion objective lens with a high numerical aperture to image the microscopic details with minimal spherical aberrations and a small depth of focus. Preliminary results from a pilot study of imaging skin lesions in vivo showed that the CPM device could reveal three-dimensional distribution of pigmented cells and intracellular distribution of pigment. Co-registered CPM and reflectance confocal microcopy images showed good correspondence between dark, brown cells in CPM images and bright, melanin-containing cells in reflectance confocal microscopy images. Lay Description: We present the development of a simple, handheld cross-polarized microscope (CPM) and demonstration of imaging individual pigmented cells in human skin in vivo. In the CPM device, the cross-polarized detection approach is used to reduce the specular reflection from the skin surface and preferentially detect multiply-scattered light. The multiply-scattered light works as back illumination from within the tissue towards the skin surface, and superficial pigment such as intraepidermal melanin absorbs some spectral bands of the multiply-scattered light and cast colored shadows. Since the light that interacted with the superficial pigment only needs to travel a short distance before it exits the skin surface, microscopic details of the pigment can be preserved. Preliminary results from a pilot study of imaging skin lesions in vivo showed that the CPM device could reveal three-dimensional distribution of pigmented cells and intracellular distribution of pigment. Co-registered CPM and reflectance confocal microcopy images showed good correspondence between dark, brown cells in CPM images and bright, melanin-containing cells in reflectance confocal microscopy images. This article is protected by copyright. All rights reserved.

Investigation of flexural, inter delamination and impact behaviour of fiber metal laminate composite

This paper deals with the experimental analysis of composite laminate made up of Basalt fiber and Aluminium. Basalt is an igneous rock composed mainly of plagioclase and pyroxene minerals. When combined with Aluminium which is a silvery-white, soft, non-magnetic and ductile metal in the boron group, its mechanical properties are enhanced, so that it can be used in different engineering applications. Basalt - Aluminium laminate is fabricated with the help of hand lay-up method. In order to enhance abrasive and durable properties, silicon carbide is added. The Basalt - Aluminium laminate is tested for the flexural and impact strength along with the delamination test to find out its inter-molecular structure. This material can be applied in places where mechanical forces occur more regularly or frequently like brake pads, clutch plates, conveyor belts, etc., In this paper Tit is proven that the addition of SiC increases the flexural strength of the material. Furthermore, it is found that the impact strength increases propositional to the weight percentage of Sic added. Inner layers of the composite and the results of the ultimate break load applied to each of the composite material with closer examination using handheld microscope is also conducted.

Surface topography characterization using a simple optical device and artificial neural networks

State-of-the-art methods for quantifying wear in cylinder liners of large internal combustion engines for stationary power generation require disassembly and cutting of the examined liner. This is followed by laboratory-based high-resolution microscopic surface depth measurement that quantitatively evaluates wear based on bearing load curves (also known as Abbott-Firestone curves). Such reference methods are destructive, time-consuming and costly. The goal of the research presented here is to develop nondestructive yet reliable methods for quantifying the surface topography. A novel machine learning framework is proposed that allows prediction of the bearing load curves representing the depth profiles from reflection RGB images of the liner surface. These images can be collected with a simple handheld microscope. A joint deep learning approach involving two neural network modules optimizes the prediction quality of surface roughness parameters as well. The network stack is trained using a custom-built database containing 422 perfectly aligned depth profile and reflection image pairs of liner surfaces of large gas engines. The observed success of the method suggests its great potential for on-site wear assessment of engines during service.

Rapid non-destructive method to phenotype stomatal traits

BackgroundStomata are tiny pores on the leaf surface that are central to gas exchange. Stomatal number, size and aperture are key determinants of plant transpiration and photosynthesis, and variation in these traits can affect plant growth and productivity. Current methods to screen for stomatal phenotypes are tedious and not high throughput. This impedes research on stomatal biology and hinders efforts to develop resilient crops with optimised stomatal patterning. We have developed a rapid non-destructive method to phenotype stomatal traits in three crop species: wheat, rice and tomato.ResultsThe method consists of two steps. The first is the non-destructive capture of images of the leaf surface from plants in their growing environment using a handheld microscope; a process that only takes a few seconds compared to minutes for other methods. The second is to analyse stomatal features using a machine learning model that automatically detects, counts and measures stomatal number, size and aperture. The accuracy of the machine learning model in detecting stomata ranged from 88 to 99%, depending on the species, with a high correlation between measures of number, size and aperture using the machine learning models and by measuring them manually. The rapid method was applied to quickly identify contrasting stomatal phenotypes.ConclusionsWe developed a method that combines rapid non-destructive imaging of leaf surfaces with automated image analysis. The method provides accurate data on stomatal features while significantly reducing time for data acquisition and analysis. It can be readily used to phenotype stomata in large populations in the field and in controlled environments.

Practical Application of Digital Image Processing in Measuring Concrete Crack Widths in Field Studies

Cracking in concrete structures is a ubiquitous problem and affects the serviceability of such structures. In many cases, it is imperative to properly measure and monitor a crack’s size to identify locations for repair and rehabilitation. This paper describes two field studies that used digital image processing to measure the width of cracks in concrete structures. The first field study compared crack measurements from digital image processing, a handheld microscope, and a crack gauge card. In the second field study, digital image processing was used to measure end region cracks in precast pretensioned concrete girders. Guidance is provided for engineers who wish to use digital image processing in field studies. Conditions where digital image processing may lead to errors are identified, and limitations of the methods are discussed. In general, the studies demonstrate that image processing methods can efficiently measure the size of cracks in concrete structures in field settings and that image-based measurements are comparable to microscope measurements.

An ultrasensitive detection platform for cocaine: Aptasensing strategy in capillary tube.

Cocaine as a detrimental addictive drug threats human health through inducing heart problem, blood pressure, anxiety, immunodeficiency, paranoia, and organ damage. Thus, the quantification of cocaine in the biological samples by a simple, high specificity, and fast method is highly urgent to decrease the harmful effect of the misuse of this drug. In this study, we constructed a novel fluorescent aptasensor by combining the fluorescein (FAM)-modified specific aptamer and AuNPs in a capillary tube as the sensing substrate for the first time. The presence of cocaine recovered the fluorescence response of the aptasensor through interaction with the aptamer and differentiation of the aptamer@AuNPs complex. By fluorescence microscopy imaging of the aptasensor substrate and its quantitative analysis, a remarkable linear range from 100pM to 600µM and the ultra-low limit of detection (LOD) as 0.31pM were achieved for the target detection. Cocaine was successfully quantified in the real samples (human serum and urine) by using the aptasensor. The aptasensor is simple, easy-to-use, favorable applicability, and cost-effective; and to the best of our knowledge, it is the first use of the capillary tube as a sensing platform just by using about 3μl of the samples. It is also an easy-to-carry tool, promising for the on-site target detection. Besides, it can be a portable device for monitoring cocaine by using a handheld single-beam fluorescence microscope. It can be an appropriate detection tool in forensic science and medicine.

Machine Learning-Based Quantification of (-)-trans-Δ-Tetrahydrocannabinol from Human Saliva Samples on a Smartphone-Based Paper Microfluidic Platform.

(−)-trans-Δ-Tetrahydrocannabinol (THC) is a major psychoactive component in cannabis. Despite the recent trends of THC legalization for medical or recreational use in some areas, many THC-driven impairments have been verified. Therefore, convenient, sensitive, quantitative detection of THC is highly needed to improve its regulation and legalization. We demonstrated a biosensor platform to detect and quantify THC with a paper microfluidic chip and a handheld smartphone-based fluorescence microscope. Microfluidic competitive immunoassay was applied with anti-THC-conjugated fluorescent nanoparticles. The smartphone-based fluorescence microscope counted the fluorescent nanoparticles in the test zone, achieving a 1 pg/mL limit of detection from human saliva samples. Specificity experiments were conducted with cannabidiol (CBD) and various mixtures of THC and CBD. No cross-reactivity to CBD was found. Machine learning techniques were also used to quantify the THC concentrations from multiple saliva samples. Multidimensional data were collected by diluting the saliva samples with saline at four different dilutions. A training database was established to estimate the THC concentration from multiple saliva samples, eliminating the sample-to-sample variations. The classification algorithms included k-nearest neighbor (k-NN), decision tree, and support vector machine (SVM), and the SVM showed the best accuracy of 88% in estimating six different THC concentrations. Additional validation experiments were conducted using independent validation sample sets, successfully identifying positive samples at 100% accuracy and quantifying the THC concentration at 80% accuracy. The platform provided a quick, low-cost, sensitive, and quantitative point-of-care saliva test for cannabis.

Unclonable Features via Electrospraying of Bulk Polymers

The ability to encode unclonable information using low-cost materials and processes is of significant interest for anti-counterfeiting and information security applications. In this study, we present a versatile approach based on electrospraying of polymer solutions to generate randomly positioned complex features as a form of physically unclonable function (PUF). The key advantage of this approach is that readily available low-cost bulk polymeric materials can form small and complex features using a simple process. Polymers of varying composition and molecular weight, together with different solvents and electrospraying conditions, are systematically explored to construct the parameter space for PUFs of varying characteristics. Besides the randomness in the spatial positions and sizes of features, the key advantage of the presented approach is the ability to generate complex 3D shapes, which are very difficult, if not impossible to fabricate with the most advanced fabrication techniques. The inclusion of photoluminescent molecules establishes an additional security layer. The additive nature of operation enables multiplexing, i.e., deposition of multiple materials on the same substrate. The fabricated PUFs have an average uniformity of 0.533 and uniqueness of 0.495, which are highly close to an ideal value of 0.5. The authentication is effectively performed using a feature detection algorithm without the need for markers and precisely defined rotation angles, greatly relaxing constraints associated with the imaging. Direct application of PUFs on the label of goods and authentication via a handheld microscope demonstrate the practical utility of the presented approach.

Handheld and Cost-Effective Fourier Lightfield Microscope.

In this work, the design, building, and testing of the most portable, easy-to-build, robust, handheld, and cost-effective Fourier Lightfield Microscope (FLMic) to date is reported. The FLMic is built by means of a surveillance camera lens and additional off-the-shelf optical elements, resulting in a cost-effective FLMic exhibiting all the regular sought features in lightfield microscopy, such as refocusing and gathering 3D information of samples by means of a single-shot approach. The proposed FLMic features reduced dimensions and light weight, which, combined with its low cost, turn the presented FLMic into a strong candidate for in-field application where 3D imaging capabilities are pursued. The use of cost-effective optical elements has a relatively low impact on the optical performance, regarding the figures dictated by the theory, while its price can be at least 100 times lower than that of a regular FLMic. The system operability is tested in both bright-field and fluorescent modes by imaging a resolution target, a honeybee wing, and a knot of dyed cotton fibers.

Patterns of the use of reflectance confocal microscopy at a tertiary referral dermatology clinic

To the Editor: Imaging using reflectance confocal microscopy (RCM) allows noninvasive examination of the skin in real time at the bedside, with cellular-level resolution. At the Memorial Sloan Kettering Cancer Center, we have been using RCM, both the arm-mounted, wide-probe microscope (Vivascope 1500, Caliber ID) and the hand-held, portable microscope (Vivascope 3000, Caliber ID), at our dermatology and dermatologic surgery clinics since 2011.1 The hand-held microscope is currently not reimbursable, and we do not bill for it.

Role of early foldscopy (microscopy) of endotracheal tube aspirates in deciding restricted empirical therapy in ventilated patients

PurposePrevention of healthcare-associated infections (HAI) like ventilator associated pneumonia (VAP) is particularly challenging especially in resource limited settings. Complex microbial interactions between patients and health care workers (HCWs) further complicate the situation, requiring a holistic approach for successful management. To bridge the gap between laboratory and intensive care unit (ICU) this study was conducted to find the role of hand-held microscope ‘Foldscope’ in restricting empirical therapy in intubated patients. MethodsA total of 75 endotracheal aspirates (ETA) were collected from intubated patients in the ICU with (group 1) and without (group 2) VAP. For group 2, those with less than 48 ​h ventilation and with endotracheal tube (ETT) in situ were considered. Presence of biomass was detected through foldscope and ETA samples were processed for quantitative gram staining (QGS), semi-quantitative and quantitative culture. Phenotypic and genotypic characterization of Acinetobacter baumannii, the commonest isolate, was done and findings were statistically analysed. ResultsBiomass was present as seen through a foldscope in 45 cases (90%) in group 1 and 17 cases (68%) in group 2. In both the groups, A. baumannii was the most common isolate. Biomass production, significant QGS and culture was significantly more in group 1 (p ​< ​0.05). However, carbapenem resistant A. baumannii (CRAB) was comparably present in both the groups thus showing limited role of empirical carbapenem therapy. ConclusionsEarly assessment of biomass in mechanically ventilated patients could provide guidance for empirical antibiotic therapy. Foldscope proved to be an excellent tool for restricting empirical therapy and driving antimicrobial stewardship in low resource settings.

Usefulness of an Inexpensive, Battery-Powered, Handheld Microscope in Low-Resource Dermatologic Practices.

Usefulness of an Inexpensive, Battery-Powered, Handheld Microscope in Low-Resource Dermatologic Practices.

In situ Observations of Porcine Ocular Surface Cells with Handheld 2K-pixel Microscope

Introduction: To present our findings of the porcine ocular surface that were obtained with an ultra-compact hand-held microscope that weighs less than 500 g, we examined the corneal epithelial cells with this hand-held microscope. Methods: This device is equipped with an automatic focusing mechanism that enabled us to observe living cells in macro to micro magnifications with a series of operations. The focus is semi-automatically adjusted by the infrared and ultrasonic distance sensor. The instrument has a commercially-available microscope objective lens of 20x or 40x magnification and has a high-resolution 2K Complementary Metal-Oxide-Semiconductor (CMOS) camera. The theoretical spatial resolution is around 300 nm with a higher Numerical Aperture (high-NA) lenses. The widefield reflectance-based imaging system is equipped with three-color visible Light-Emitting Diodes (LEDs) for use in bright environments and an infrared LED for dark environments. Ten normal and two injured porcine corneas were examined with this hand-held microscope. Results: Our observations showed that the corneal and conjunctival epithelial cells could be continuously observed. The epithelial cells of the central cornea, limbus, and conjunctiva were clearly seen. The epithelial cells on the injured corneal surface were also easily and clearly observed. Conclusion: This hand-held microscopic imaging device allows medical health care workers such as ophthalmologists and endoscopists to obtain real-time in vivo optical biopsies without collecting tissues and cells. Our system enables us to observe single cells in the superficial layers without any fluorescein or other dyes.

Physicochemical characterization of building and painting materials from the Ptolemaic Osirian catacombs of Karnak temples, Upper Egypt

This study reports the first analytical study conducted on samples of fired bricks, bedding mortar and plaster layers collected from the catacombs of Ptolemy IV Philopator at Karnak temples, Upper Egypt. These unique constructions comprise three-level rectangular vaulted brick shrines that lined up in three passages. The microscopic particularities of the samples were assessed by digitalized optical handheld microscope, while the petrographic analysis was depicted by polarized light microscope. X-ray diffractometer was used to analyse some brick, mortar and plaster samples. The morphological description and microchemical analysis, on various points in the samples, were attained via the field-emission scanning electron microscope with an energy-dispersive X-ray spectrometer. Further, the molecular and vibrational attributions of some fragments and pigment grains were recognized using Fourier transform infrared spectrometer and Raman microspectrometer (µ-Raman). Results showed that the studied bricks were fired at low temperature using poor-calcium clays. The cross-sectional observation on the plaster layers defined three layers, which are mainly made up of calcium carbonate (calcite). Minerals of quartz, rutile, plagioclase feldspars and calcium silicate were identified, in varying proportions, in the studied plasters. Pigments as Egyptian blue, yellow ochre and red ochre were characterized along the plaster layers. Likely, the microscopic examination and the molecular analysis of the samples disclosed that “fresco” technique was used to decorate the catacombs.

A Smartphone-Based Fluorescence Microscope With Hydraulically Driven Optofluidic Lens for Quantification of Glucose

The traditional method for early diagnosis of diabetes is to detect urine or blood glucose levels. However, the present clinical detection methods cause either cross-infection or require expensive instruments with complex procedures of operation. In this work, a handheld smartphone-based fluorescence microscope with the tunable optofluidic lens and microfluidic assay is demonstrated for the facile detection of glucose concentration for the first time to our knowledge. The tunability of the optofluidic lens is based on the dynamic deformation of an elastomeric membrane driven by adjustable hydraulic pressure. And the glucose sensor integrates a smartphone, a tunable optofluidic lens, a microfluidic chip, a customized holder and some easily accessible optics. A low detection limit of 0.33 mM of glucose was achieved subjected to a linear range of detection from 0 to 6 mM glucose, which is evaluated with an enzymatic fluoresce method. These results show that the cost-effective miniaturized system can be used for early screening and diagnosis of diabetes and potentially some other onsite applications of clinical diagnosis and environment monitoring.

492 The usefulness of an inexpensive, battery-powered, handheld microscope in low-resource dermatologic practices

Previous studies in low- and middle-income countries have shown that skin disease is very common, especially dermatophyte and scabies infections. Point-of-care microscopic evaluation of skin scraping samples improves the diagnostic accuracy of these skin pathologies. Resource limitations, however, often preclude the use of microscopy for point-of-care evaluations in low- and middle-income countries. An inexpensive (<USD$20), hand-held, battery-powered LED microscope was field-tested for potassium hydroxide (KOH) and mineral oil examinations of skin scrapings from participants who complained of a rash. The study was conducted in collaboration between the University of Utah School of Medicine and the Kwame Nkrumah University of Science & Technology School of Medical Sciences in the Atwima Nwabiagya North District in the Ashanti region of Ghana, West Africa. A board-certified dermatologist was able to microscopically confirm dermatophyte and scabies infections, which comprised 16.4% (35/213) of all evaluated skin conditions. An inexpensive, hand-held, battery-powered LED microscope can be used to effectively diagnose certain skin diseases in remote locations without the need for electricity. This point-of-care testing is readily learnable by any clinician, staff member or pharmacist. Using microscopy improves the diagnostic accuracy of skin conditions and choice of therapy and minimizes unnecessary side effects of commonly-used combination treatments.

Real-time video mosaicking to guide handheld in vivo microscopy.

Handheld and endoscopic optical-sectioning microscopes are being developed for noninvasive screening and intraoperative consultation. Imaging a large extent of tissue is often desired, but miniature in vivo microscopes tend to suffer from limited fields of view. To extend the imaging field during clinical use, we have developed a real-time video mosaicking method, which allows users to efficiently survey larger areas of tissue. Here, we modified a previous post-processing mosaicking method so that real-time mosaicking is possible at >30 frames/second when using a device that outputs images that are 400 × 400 pixels in size. Unlike other real-time mosaicking methods, our strategy can accommodate image rotations and deformations that often occur during clinical use of a handheld microscope. We perform a feasibility study to demonstrate that the use of real-time mosaicking is necessary to enable efficient sampling of a desired imaging field when using a handheld dual-axis confocal microscope.

Smartphone-integrated field microscopy (SPFM): a low-cost and portable tool to study live biological specimens in the wild

Images and videos of organisms recorded in the wild have relevance for biodiversity studies. With the advent of smartphones and their potential integration with microscopy, scientific documentation and recording of organisms has surged to an unprecedented scale. Here we report a novel method, developed by integration of a portable smartphone with a handheld field microscope that we term Smartphone-integrated Field Microscopy (SPFM), to capture images and videos which can be highly useful in field-based biodiversity studies. We firstly describe the design of the method and equipment used, followed by successful field demonstration of the method using a case study of the gymnosperm Ephedra intermedia Schrenk & C. A. Meyer in the Kashmir Himalaya. We then discuss the novelty of our method and its potential applications in biodiversity studies.