Enzyme embedded microfluidic paper-based analytic device (μPAD): a comprehensive review

Quantitative pH Determination Based on the Dominant Wavelength Analysis of Commercial Test Strips

“…Particularly, pH imbalance is considered a sign of cancer because most solid malignant tumors with increased glycolysis and insufficient perfusion would produce an acidic extracellular environment, thereby promoting tumor growth, invasion, and metastasis . In addition to the use of commercial pH test strips for pH quantitation, such a platform technology can be adapted for the colorimetric detection of other disease biomarkers/indicators in human urine and serum. − Of course, besides medical diagnosis, its application for the detection of environmental pollutants and food shall be also explored. − With the development of upgraded smartphone cameras (i.e., with improved color depth), we can further improve the sensitivity and accuracy of pH quantification with the Smart-pH-Reader system in order to satisfy pH quantitation in diverse application fields.…”

Microfluidic Immobilized Enzymatic Reactors for Proteomic Analyses—Recent Developments and Trends (2017–2021)

“…From this point of view there are three main types of enzyme reactors: (1) wall-coated IMERs, where the enzyme is directly adsorbed/attached on the inner surface of the empty [12,13] or micropatterned (e.g., micropillar array [14]) microchannels; (2) packed/fixed-bed IMERs, where the enzyme is immobilized to a support material (particles, beads) that can be homogeneously packed into the microfluidic system [15,16]; and (3) monolithic IMERs, where the enzyme is immobilized onto the microscopic pores and channels provided by the network of the meso-and macro-porosity of a monolith-type material [17,18] (Figure 1). There are several other solid supports used in µ-IMERs, which apply slightly other approaches through membrane- [19,20], paper- [21] or gel-based [22,23] supports. Although the simplest realization of enzyme immobilization can be achieved on the channel interior/wall itself, the most often used classical way to increase the S/V of the support is the application of a micropacking or membrane.…”

Rapid and inexpensive process to fabricate paper based microfluidic devices using a cut and heat plastic lamination process

“…2 The miniaturization of multiple laboratory functions into paper-based chips integrated with faster responses has opened up new opportunities in the field of low-cost portable point of care diagnostics. [3][4][5] MicroPADs have shown potential use for various fluidic applications such as food safety and processing, [6][7][8][9][10][11] environmental monitoring, [11][12][13][14][15] cell biology, 14,16 drug screening 17,18 and clinical diagnosis. 11,[19][20][21][22] Several techniques have been demonstrated in the literature to pattern paper substrates for the fabrication of microPADs.…”

“…[3][4][5] MicroPADs have shown potential use for various fluidic applications such as food safety and processing, [6][7][8][9][10][11] environmental monitoring, [11][12][13][14][15] cell biology, 14,16 drug screening 17,18 and clinical diagnosis. 11,[19][20][21][22] Several techniques have been demonstrated in the literature to pattern paper substrates for the fabrication of microPADs. Fundamentally, the shapes of microfluidic pathways, such as channels and reservoirs, can be created in paper sheets either by (i) the physical blocking of pores in the areas of the sheet external to the desired shape via patterning using a hydrophobic medium such as photoresist, ink, wax, PDMS, or other materials, or by (ii) cutting the paper sheet in the desired pattern using a craft cutter or laser cutter to create a stand-alone paper device in the desired shape.…”