Simultaneous quantitative detection of hematocrit and hemoglobin from whole blood using a multiplexed paper sensor with a smartphone interface

On paper characterisation of droplet and evaporation study using impedance spectroscopy

The development of paper-based devices has drawn a significant amount of attention, ranging from the creation of paper electronics to microfluidic devices. The flow of fluids through the paper substrate can be controlled by establishing a variety of barriers, which can be accomplished by either cutting or producing layers that are hydrophobic. Through the utilisation of this feature, a number of investigations, including mixing, modifying, and analytical studies, have been carried out on the paper substrate. However, because of the difficulties associated with its wettability, it is seldom investigated for the purpose of conducting evaporation studies of droplets. Traditionally, evaporation studies are carried out on a solid substrate like glass or silicon. Here we report a paper chip employing an impedance method to determine the characteristics of the droplet. It is also possible to determine the identity of the droplet by utilising the dielectric property of the liquid on a paper chip. A comparison is made between the traditional method of evaporation and the usage of the paper chip for the purpose of studying the evaporation of various liquids, ranging from ionic chemicals to volatile compounds. A subsequent step involves the utilisation of an electrical equivalent circuit in order to acquire the complex system attribute of the evaporation of the cellulose fibres. Finally, this reveals that paper chips have a significant amount of promise for use in scientific applications regarding evaporation analysis.

Development of a Paper-based Hematocrit Test and a Lateral Flow Assay to Detect Critical Fibrinogen Concentrations Using a Bottom-Up Pyramid Workflow Approach

Fibrinogen is a coagulation factor in human blood and the first one to reach critical levels in major bleeding. Hypofibrinogenemia (a too low fibrinogen concentration in blood) poses great challenges to first responders, clinicians, and healthcare providers since it represents a risk factor for exsanguination and massive transfusion requirements. Thus, the rapid assessment of the fibrinogen concentration at the point of care has gained considerable importance in preventing and managing major blood loss. However, in whole blood measurements, hematocrit variations affect the amount (volume fraction) of plasma that passes the detection zone. In an attempt to accurately determine realistic critical levels of fibrinogen (<1.5 mg/mL) in patients needing immediate treatment and medical interventions, we have developed novel diagnostic systems capable of estimating hematocrit and critical fibrinogen concentrations. A lateral flow assay (LFA) for the detection of fibrinogen has been developed by establishing a workflow employing rapid characterization methods to streamline LFA development. The integration of two detection lines enables (i) the identification of fibrinogen (first line) present in the sample and (ii) the determination of the clinically critical fibrinogen concentrations below 1.5 mg/mL (second line). Furthermore, the paper-based separation of blood cells from plasma provides a semiquantitative estimate of the hematocrit by analyzing the fractions. Initial validation of the point-of-care (PoC) hematocrit test revealed good comparability to a standard laboratory method. The developed diagnostic systems have the ability to accelerate decision-making in cases with major bleeding.