Measurement of sucrose concentration using Imbibition length on paper: A device for equipment-free and environmentally-friendly detection.

The Lucas-Washburn equation is commonly used to predict the distance (L) that a liquid travels through paper. This equation establishes that L is linear with time and inversely proportional to the viscosity of the liquid. However, there is currently no theoretical equation connecting the viscosity of a solution to its concentration.

Simple and Equipment-Free Paper-Based Device for Determination of Mercury in Contaminated Soil.

This work presents a simple and innovative protocol employing a microfluidic paper-based analytical device (µPAD) for equipment-free determination of mercury. In this method, mercury (II) forms an ionic-association complex of tetraiodomercurate (II) ion (HgI) using a known excess amount of iodide. The residual iodide flows by capillary action into a second region of the paper where it is converted to iodine by pre-deposited iodate to liberate I under acidic condition.

Paper-based colorimetric biosensor of blood alcohol with in-situ headspace separation of ethanol from whole blood.

This work presents a novel development that exploits the concept of in-situ gas-separation together with a specific enzymatic colorimetric detection to produce a portable biosensor called "Blood Alcohol Micro-pad" for direct quantitation of ethanol in whole blood. The thin square device (25 mm × 25 mm × 1.8 mm) comprises two layers of patterned filter paper held together with a double-sided mounting tape with an 8-mm circular hole (the headspace).

T-shirt ink for one-step screen-printing of hydrophobic barriers for 2D- and 3D-microfluidic paper-based analytical devices.

This work presents the use of polyvinyl chloride (PVC) fabric ink, commonly employed for screening t-shirts, as new and versatile material for printing hydrophobic barrier on paper substrate for microfluidic paper-based analytical devices (μPADs). Low-cost, screen-printing apparatus (e.g.

Highly sensitive and selective electrochemical paper-based device using a graphite screen-printed electrode modified with molecularly imprinted polymers coated FeO@Au@SiO for serotonin determination.

Herein, we propose a highly sensitive and selective three-dimensional electrochemical paper-based analytical device (3D-ePAD) to determine serotonin (Ser). It uses a graphite-paste electrode modified with nanoparticles coated with molecularly imprinted polymer (MIP). FeO@Au nanoparticles were encapsulated with silica to create novel nano-sized MIP.

Simple and green method for direct quantification of hypochlorite in household bleach with membraneless gas-separation microfluidic paper-based analytical device.

This work presents development of a microfluidic paper-based analytical device (µPAD) for direct determination of hypochlorite in household bleach. The recent design of a membraneless gas-separation microfluidic paper-based analytical device (MBL-GS µPAD) was employed to fabricate the hypochlorite-µPAD. Chlorine gas is generated in the µPAD via acidification of an aliquot of sample loaded on to the donor reservoir located at the bottom layer of the μPAD.

Membraneless Gas-Separation Microfluidic Paper-Based Analytical Devices for Direct Quantitation of Volatile and Nonvolatile Compounds.

This work presents new chemical sensing devices called "membraneless gas-separation microfluidic paper-based analytical devices" (MBL-GS μPADs). MBL-GS μPADs were designed to make fabrication of the devices simple and user-friendly. MBL-GS μPADs offer direct quantitative analysis of volatile and nonvolatile compounds.

Simultaneous determination of iodide and creatinine in human urine by flow analysis with an on-line sample treatment column.

This work presents the first flow system for direct analysis of iodide and creatinine suitable for screening of human urine samples. The system had a mini-column packed with strong anion exchange resin for on-line extraction of iodide. After injection of a sample on the column the unretained urine sample was analyzed for creatinine in one section of the flow system using the Jaffe's reaction with spectrometric detection at 520 nm.