A Homemade Smart Phone Microscope for Single-Particle Fluorescence Microscopy

Abstract

Imaging tools advance nanoscience education by enabling students to see and engage with matter that is not visible to the human eye. However, undergraduate students generally lack access to expensive research-grade electron and optical microscopes, especially at primarily undergraduate institutions. New, inexpensive, and hands-on microscopy activities are needed to advance nanoscience education. Here we demonstrate a microscopy activity in which students assemble a total internal reflection-based fluorescence microscope using interlocking building bricks and image a series of micrometer- and nanometer-sized fluorescent beads. The hands-on experiments are accompanied by fluorescence image analysis, single-particle detection, and particle size measurements. The activity enables students to explore the optical diffraction limit effect that was the subject of the 2014 Nobel Prize in Chemistry. This activity introduces undergraduate students to underlying principles of optical microscopy, optical components and light sources, Snell’s law, and image processing and analysis procedures while reinforcing major concepts like data analysis and statistics, fluorescence, emission, and absorption.

Photonics enabled intelligence system to identify SARS-CoV 2 mutations

“…Various techniques have been employed to address this issue. Many papers have been published on bio-sensing for SARS-CoV-2, which uses direct immunoassays for amplification-free DNA or RNA biosensing (Pinheiro et al 2021 (Mu et al 2019), homemade smartphone using total internal reflection microscopy (Varra et al 2020), and multi-modal smartphone (bright-field, oblique illumination dark-field, and total internal reflection dark-field) on a single platform (Rabha et al 2021). An optical sensor device connecting through the 5 G network allows the Internet of Things (IoT) to identify single nucleic acids SARS-CoV 2 (Guo et al 2021).…”

Learning about Fluorescence in Undergraduate Biochemistry: Enzyme Kinetics Using a Low-Cost, Student-Built Fluorescence Spectrometer

“…27,28 Recently, Varra et al utilized interlocking building bricks, small optical components, and a smartphone camera to generate a fluorometer capable of monitoring singleparticle fluorescence. 34 Silva et al developed a low-cost spectrometer by mounting a diffraction grating onto a webcam and then utilized this device to record absorbance and fluorescence spectra of various analytes in real time. 35 Other designs are also reported in the literature.…”

“…Various low-cost fluorometers have been developed for a variety of different applications. For example, Kvittingen and co-workers used LEDs as both a light source and detector (as described by Pokrzywnicka et al) to create a single-beam fluorescence spectrophotometer primarily out of interlocking building bricks. , Recently, Varra et al utilized interlocking building bricks, small optical components, and a smartphone camera to generate a fluorometer capable of monitoring single-particle fluorescence . Silva et al developed a low-cost spectrometer by mounting a diffraction grating onto a webcam and then utilized this device to record absorbance and fluorescence spectra of various analytes in real time .…”

Teaching chemistry with LEGO® bricks

“…In some activities in which the students built a full-fledged visible spectrophotometer (Bougot-Robin, Paget, Atkins, & Edel, 2016;Knagge & Raftery, 2002;Wilson & Wilson, 2017) and a fluorescence microscope (Varra et al, 2020), LEGO bricks were employed as the frame of the instruments or as holders to secure the components, such as the slit, mirror, prism, and quartz cell. In some reports, a hole was drilled in the LEGO brick to create the moving part of the spectrometer.…”