Design and Optimization of Piezoresistive PEO/PEDOT:PSS Electrospun Nanofibers for Wearable Flex Sensors.

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

doi:10.3390/nano10112166

Abstract

Flexible strain sensors are fundamental devices for application in human body monitoring in areas ranging from health care to soft robotics. Stretchable piezoelectric strain sensors received an ever-increasing interest to design novel, robust and low-cost sensing units for these sensors, with intrinsically conductive polymers (ICPs) as leading materials. We investigated a sensitive element based on crosslinked electrospun nanofibers (NFs) directly collected and thermal treated on a flexible and biocompatible substrate of polydimethylsiloxane (PDMS). The nanostructured active layer based on a blend of poly(ethylene oxide) (PEO) and poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonate) (PEDOT:PSS) as the ICP was optimized, especially in terms of the thermal treatment that promotes electrical conductivity through crosslinking of PEO and PSS, preserving the nanostructuration and optimizing the coupling between the sensitive layer and the substrate. We demonstrate that excellent properties can be obtained thanks to the nanostructured active materials. We analyzed the piezoresistive response of the sensor in both compression and traction modes, obtaining an increase in the electrical resistance up to 90%. The Gauge Factors (GFs) reflected the extraordinary piezoresistive behavior observed: 45.84 in traction and 208.55 in compression mode, which is much higher than the results presented in the literature for non-nanostructurated PEDOT.

Highlights

In the last decade, flexible and wearable electronic devices have gained increasing attention for application in several areas, ranging from healthcare and sports to space exploration and soft robotics [1,2,3]
PEDOT thin film-based sensors presented in literature have a Gauge Factors (GFs) up to 17.8 [7,65,68,69,70]
A plastic behavior of nanofibers when the mechanical test is conducted at angular deformation higher than 90◦ is observed

Summary

Introduction

Flexible and wearable electronic devices have gained increasing attention for application in several areas, ranging from healthcare and sports to space exploration and soft robotics [1,2,3]. Advancement in flexible sensors are largely responsible for the progress of wearable systems, and strain sensors received special attention by several application fields, such as health monitoring devices [4,5], artificial skin [6,7,8] and prosthetic limbs [9,10,11]. Strain sensors used in body joint monitoring are part of a subcategory of strain sensors named Flex Sensors. They sense the angular deformation rather than linear deformation [14]. The demand for wearable, highly deformable, soft and light-weight flex sensors is ever increasing [18]

Methods

Results

Conclusion