Electrochemical Impedance Spectroscopy characterization of a microfluidic paper-based device for the evaluation of prothrombin time

LAZARTE, LUCIANA; BARRAZA, DANIELA E.; ALEMÁN, MARIANO; MADRID, ROSSANA E.

Buenos Aires

Workshop; II Brazil-Argentine Microfluidics Congress and V Congreso de Microfluídica Argentina; 2022

Microfluídica Argentina

Prothrombin time (PT) test to evaluate the activity of the extrinsic coagulation pathway (alsocalled the tissue factor pathway) is assessed in biochemistry laboratories (BL) in a blood sample.The PT is commonly used to monitor warfarin anticoagulant therapy, so patients under treatmentneed periodically attend the BL for monitoring. With increasing numbers of anticoagulatedpatients, there is a growing need to develop low-cost portable tests that will allow them to checkin the comfort of their own homes whether they have overdone their dose in order to detectdangerous alterations and to come to the hospital to confirm the result and make adjustments1.In recent years, paper has become an alternative for advanced microfluidic devices, being used as aplatform or support for various analytical and bioanalytical techniques2. This work proposes themanufacturing of a paper-based microfluidic device, which through electrochemical impedancespectroscopy (EIS), allows to reproduce the PT test. Whatman N°1 paper was used to fabricatethe paper chip. Hydrophobic zone was generated with the wax printing technique, using a solidink printer. Carbon electrodes were silk-screened to obtain the proposed device (Figure1). Thefollowing test were proposed to evaluate the EIS performance of the chip to reproduce the PTtest: a) Evaluation of the optimal work volume and b) Evaluation of the incorporation of theFerricyanide–Ferrocyanide Redox Couple (Ferro/Ferri) to the PT test. Considering the electricalRandles model, the solution resistance (Rm) and the charge transfer resistance (Rct) obtainedby adequately fitting the response to a circle, were analyzed. The obtained results allowed toestablish a) that the optimal working volume for this microfluidic device is 10 µl, reducing inthis way the reagents volumes by 20 times comparing with the automatic traditional method,and b) no statistically significant differences were determined in the percent variation of Rctvalues between measurements, regardless of whether the Ferro/Ferri was present or not in thePT assay (Figure 2). The developed paper-based microfluidic device was easy to manufactureand represents a future alternative to perform the PT test by EIS.