Broadly Available Imaging Devices Enable High-Quality Low-Cost Photometry

Abstract

This paper demonstrates that, for applications in resource-limited environments, expensive microplate spectrophotometers-which are used in many central laboratories for parallel measurement of absorbance of samples-can be replaced by photometers based on inexpensive and ubiquitous, consumer electronic devices (e.g., scanners and cell-phone cameras). Two devices-i) a flatbed scanner operating in transmittance mode and ii) a camera-based photometer constructed from a cell phone camera, a planar light source, and a cardboard box-demonstrate the concept. These devices illuminate samples in microtiter plates from one side, and use the RGB-based imaging sensors of the scanner/camera to measure the light transmitted to the other side. The broadband absorbance of samples (RGB-resolved absorbance) can be calculated using the RGB color values of only three pixels per micro-well. Rigorous theoretical analysis establishes a well-defined relationship between the absorbance spectrum of a sample and its corresponding RGB-resolved absorbance. The linearity and precision of measurements performed with these low-cost photometers on different dyes that absorb across the range of the visible spectrum, and chromogenic products of assays (e.g., enzymatic, ELISA) demonstrates that these low-cost photometers can be used reliably in a broad range of chemical and biochemical analyses. The ability to perform accurate measurements of absorbance on liquid samples, in parallel and at low cost, would enable testing, typically reserved for well-equipped clinics and laboratories, to be performed in circumstances where resources and expertise are limited.

Determinação de fosfato em refrigerantes utilizando um scanner de mesa e análise automatizada de dados: um exemplo didático para ensino de química

“…Recentemente, Christodouleas et al 14 mostraram que um scanner de mesa pode substituir um leitor de microplacas, fazendo a quantificação de diversos corantes e leituras de placas de teste ELISA (ensaio de imunoabsorção enzimática, Enzyme-Linked Immunosorbent Assay).…”

Scanometry as microplate reader for high throughput method based on DPPH dry reagent for antioxidant assay

“…A scanometry has been used as a microplate reader for high throughput screening of antioxidant based on DPPH as dry reagent on microwell plate as also used by other 28 . However, the proposed method is the first application for antioxidant sensor, measuring antioxidant capacity of GA and plant extracts.…”

“…The gray intensity, typically a result of silver enhancement is the measured signal in scanometry 27 . Scanometry was used to characterize optical feature of various dyes, such as disperse orange 3, methyl orange, fluorescein, eosin Y, rhodamine B, trypan blue, prussian blue, malachite green, methylene blue, chlorophyll b, and DPPH, in a microwell plate 28 . As the color intensity in red, green, and blue (RGB) value was mathematically converted to RGB-resolved absorbance, it was shown that flatbed scanner was comparable with spectrophotometer.…”

The world of biomedical apps: their uses, limitations, and potential

“…There are some smartphone based devices that are not found in the app stores, but there is a clear displacement of lab equipment using mobile technology, such as in the areas of microplate reading (Berg et al, 2015;Christodouleas et al 2015;Fu et al, 2016), live cell imaging (Walzik et al, 2015), microfluidics for cancer detection (Barbosa et al, 2015), food allergen detection (Coskun et al, 2013), and immunochromatgraphic detection of bacteria (Rajendran et al, 2014).Nonetheless, there are areas where no changes are expected; and this is the work of dangerous chemical and pathogens (e.g. Biohazard Class 3 work).…”