RESUMEN
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.
RESUMEN
The blood hematocrit (Hct) level provides vital information about a person's health. Traditional Hct measurement equipment relies heavily on infrastructure and skilled manpower, limiting its broad implementation in resource-limited contexts. Therefore, we developed a simple, reagent-free, non-destructive, smartphone-integrated paper-based device for Hct measurement by analyzing blood-spreading area on a paper substrate. Blood spreading area was found to be dependent on the Hct value, paper properties, and assay duration. This device was calibrated using a custom-made Python algorithm with 10 µl of blood, which produced a sensitivity of -1.90 ± 0.03 mm2/Hct (%) with a LOD as low as 2.17% Hct. The device linear range (8.8 to 58% Hct) is wide enough to cover the clinically relevant range of blood Hct (%). Furthermore, this Python algorithm was coupled with a user-friendly and clinically beneficial Android application (app) to establish an automated tool for quantitative estimation. Comparing the app performance with the result obtained from the gold standard hematology analyzer using blood from 87 subjects reveals a strong correlation (r = 0.99), an average bias of 0.15 with limits of agreement of -2.5 to 2.79 at 95% CI. The device exhibits an accuracy of 96.85% and acceptable reproducibility, with CV ranging from 0.8 to 7.5%. An integrated detection cum readout guiding pattern may allow this device to be suitable for simultaneous quantitative and qualitative estimation and to be employed in both developed and resource-limited clinical settings for Hct measurement in routine checkups and regular monitoring during critical care, as well as in the initial screening of large anemic populations.