PANI-Based Wearable Electrochemical Sensor for pH Sweat Monitoring

• Published in: Chemosensors Vol. 9; no. 7; p. 169
• Main Authors: Mazzara, Francesca, Patella, Bernardo, D’Agostino, Chiara, Bruno, Maria Giuseppina, Carbone, Sonia, Lopresti, Francesco, Aiello, Giuseppe, Torino, Claudia, Vilasi, Antonio, O’Riordan, Alan, Inguanta, Rosalinda
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.07.2021
• Subjects: Body fluids; Chemical sensors; Contact angle; Cystic fibrosis; Diabetes; electrochemical sensor; Electrodes; Graphene; Indium tin oxides; Infrared analysis; pH effects; pH sensor; polyaniline; Polyanilines; Polyethylene; Polyethylene terephthalate; Polymerization; Potassium; reduced graphene oxide; Scanning electron microscopy; Selectivity; Sensors; Substrates; Sweat; Thin films; Tin; Uric acid; wearable sensor; Wearable technology
• ISSN: 2227-9040; 2227-9040
• DOI: 10.3390/chemosensors9070169

Nowadays, we are assisting in the exceptional growth in research relating to the development of wearable devices for sweat analysis. Sweat is a biofluid that contains useful health information and allows a non-invasive, continuous and comfortable collection. For this reason, it is an excellent biofluid for the detection of different analytes. In this work, electrochemical sensors based on polyaniline thin films deposited on the flexible substrate polyethylene terephthalate coated with indium tin oxide were studied. Polyaniline thin films were abstained by the potentiostatic deposition technique, applying a potential of +2 V vs. SCE for 90 s. To improve the sensor performance, the electronic substrate was modified with reduced graphene oxide, obtained at a constant potential of −0.8 V vs. SCE for 200 s, and then polyaniline thin films were electrodeposited on top of the as-deposited substrate. All samples were characterized by XRD, SEM, EDS, static contact angle and FT-IR/ATR analysis to correlate the physical-chemical features with the performance of the sensors. The obtained electrodes were tested as pH sensors in the range from 2 to 8, showing good behavior, with a sensitivity of 62.3 mV/pH, very close to a Nernstian response, and a reproducibility of 3.8%. Interference tests, in the presence of competing ions, aimed to verify the selectivity, were also performed. Finally, a real sweat sample was collected, and the sweat pH was quantified with both the proposed sensor and a commercial pH meter, showing an excellent concordance.