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Microfluidic colorimetric biosensors have shown promising potential for detecting metal cations, anions, organic dyes, drugs, pesticides. As for today, most colorimetric sensors are read by a smartphone or professional optical imaging system, and there is still a lack of an affordable and reliable colorimetric detector for the microfluidic chip. In...
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... This significantly reduces costs related to operations and logistics [19]. With increasing digitalization, the use of smartphones has pervaded all aspects of our lives [6,20]. The integration of paper-based analytical devices with the now ubiquitous smartphone helps to capture the image of color formed on the paper substrate. ...
Rapid and effective methods for the detection of analytes such as water contaminants, food adulterants and biomolecules are essential for the protection of public health and environmental protection. Most of the currently established analytical techniques need sophisticated equipment, centralized testing facilities, costly operations, and trained personnel. Such limitations make them inaccessible to the general populace, particularly in regions with limited resources. The emergence of microfluidic devices offers a promising alternative to overcome several such constraints. This work describes a protocol for fabricating a low-cost, open-source paper-based microfluidic device using easily available tools and materials for colorimetric detection of analytes. The ease and simplicity of fabrication allow users to design customized devices. The device is coupled with an imaging box assembled from 3D printed parts to maintain uniform lighting conditions during analytical testing. The platform allows digital imaging using smartphones or cameras to instantaneously capture images of reaction zones on the device for quantitative analysis. The system is demonstrated for detecting hexavalent chromium, a toxic water contaminant. The image analysis is performed using open-source ImageJ for quantification of results. The approach demonstrated in this work can be readily adopted for a wide range of sensing applications.
... The resolution of smartphoneembedded CMOS image sensor (CIS) cameras now exceeds 20 million pixels, and the pixel pitch has been reduced to about 1 μm. Recently, smartphone optical sensors using this high pixel density have been extensively used for bioimaging medical diagnosis in microfluidics [2][3][4][5][6][7][8][9][10][11]. For example, an optical fiber surface plasmon resonance (SPR) sensor system was reported by Bremer et al. ...
With the development of hardware and software for smartphones, more and more well-designed smartphone-based imaging biosensors have been created and broadly applied in point-of-care testing (POCT). Imaging biosensors can get clear images through the high pixel density of smartphones’ camera systems. And smartphones also provide a chance for imaging processing thanks to smartphones' central processing units (CPUs) and graphics processing units (GPUs). Different approaches have extensively explored smartphone-based imaging biosensors. The commonly used imaging methods are generally implemented by the bright field with the light source or by fluorescence with a fluorescence microscope. Smartphones have enabled the widespread application of imaging-based methods in clinical chemistry, environmental monitoring, flow cytometry, food analysis, drug screening, and medical diagnostics. In detail, this article discusses various imaging biosensors and specific applications of smartphone-based imaging biosensors for bright-field imaging and fluorescence bioimaging. Meanwhile, the opportunities and challenges of smartphone-based imaging biosensors are also analyzed here.
