An electrochromic paper-based device as a diagnostic test for Cystic Fibrosis

Abstract

Cystic Fibrosis (CF) is an inherited disorder affecting more than 70000 people worldwide, especially Caucasian populations with a carrier prevalence of 1/3000. Currently, it has no cure but an early diagnosis remains a critical issue. Sweat chloride test has been the gold standard to diagnose CF since the affected present sweat chloride concentrations ≥ 60 mM. In this work, a planar electrochromic “point-of-care” device, based on tungsten trioxide nanoparticles produced by microwave assisted hydrothermal synthesis, was developed as a first approach for CF diagnostic testing especially in resource-limited environments. For electrodes patterning, a CO2 laser technology was used in a PET/ITO sheet. The device presents a design that allows the NaCl-based electrolyte deposition, used as artificial sweat, only on time of usage directly on the nanoparticles or in a paper pad. By applying an operating voltage of -3 V, the nanoparticles change their optical properties according to NaCl concentration, presenting a blue colouration with different intensities for different NaCl concentrations. The device was able to differentiate between a positive and negative diagnosis, with a colouration time of only 1 min, using an RGB analysis with a B/R ratio of 1.37±0.03 for 60 mM of NaCl, and a low power consumption.