Electrospun PEO/PEDOT:PSS Nanofibers for Wearable Physiological Flex Sensors.

Eve Verpoorten,Candido Fabrizio Pirri,Marzia Quaglio,Giulia Massaglia

doi:10.3390/s21124110

Abstract

Flexible sensors are fundamental devices for human body monitoring. The mechanical strain and physiological parameters coupled sensing have attracted increasing interest in this field. However, integration of different sensors in one platform usually involves complex fabrication process-flows. Simplification, even if essential, remains a challenge. Here, we investigate a piezoresistive and electrochemical active electrospun nanofibers (NFs) mat as the sensitive element of the wearable physiological flex sensing platform. The use of one material sensitive to the two kinds of stimuli reduces the process-flow to two steps. We demonstrate that the final NFs pH-Flex Sensor can be used to monitor the deformation of a human body joint as well as the pH of the skin. A unique approach has been selected for pH sensing, based on Electrochemical Impedance Spectroscopy (EIS). A linear dependence of the both the double layer capacitance and charge transfer re-sistance with the pH value was obtained by EIS, as well as a linear trend of the electrical resistance with the bending deformation. Gauge factors values calculated after the bending test were 45.84 in traction and 208.55 in compression mode, reflecting the extraordinary piezoresistive behavior of our nanostructured NFs.

Highlights

Francisco Falcone and Flexible and wearable devices able to sense bending are more and more developed for applications such as smart clothing, rehabilitation, prosthetic limbs, sport and research [1,2,3,4,5,6,7,8,9]
We proposed a multisensing platform based on the common sensitive element able to monitor the two signals, which implies one single and simple process flow for the whole platform
We demonstrate that the resulting polyethylene oxide (PEO)/PEDOT:PSS NFs are electrochemically active and suitable to work as the sensitive element of the electrochemical pH sensing unit

Summary

Introduction

Francisco Falcone and Flexible and wearable devices able to sense bending are more and more developed for applications such as smart clothing, rehabilitation, prosthetic limbs, sport and research [1,2,3,4,5,6,7,8,9]. Since the contractile activity of the muscles builds-up acid in muscle cells during exercise, the monitoring of sweat pH plays a crucial role to define the health state of the body, leading to correlate it to the physical activity [17,18,19]. In an out-of-the-lab perspective, personalized rehabilitation therapy can include a multisensing platform able to sense the angular deformation as well as the pH, which allows the direct monitoring of muscle fatigue during training of body joints. For this purpose, the combination of sweat-pH and joint bending information obtained by stretchable and pH-sensitive flex sensors are of huge interest for multisensing systems. Since the pH is affected by the presence of diseases such as cystic fibrosis, dehydration, diabetes and cancer [17,18,19], the multisensing system, based on flex sensor and pH sensor, plays a crucial role to establish if the pH changes are due to the physical activity or not, preventing the alert for a disease

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Conclusion