Abstract
Flexible sensors are fundamental devices for human body monitoring in application areas ranging from health care to soft robotics. During the last decade the possibility to couple sensing of mechanical strain and physiological parameters have attracted ever increasing interest to design novel, robust and low-cost wearable sensing units. Stretchable and pH sensible piezoelectric strain sensors made by blending intrinsically conductive polymers and polymeric electrolyte can serve this purpose. In this work, we specifically investigate a Crosslinked Nanofibers (NFs) Flex Sensor able to detect mechanical flection and pH change. The optimized sensitive element of the NFs Flex Sensor is based on crosslinked electrospun NFs mats made of a blend of (polyethylene oxide) PEO as the polymeric electrolyte, and poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonate) (PEDOT:PSS) as the intrinsically conductive polymer. The NFs Flex Sensor has been obtained by directly collecting the nanomaterial on a flexible and biocompatible polydimethylsiloxane (PDMS) slab and thermally treating it to promote electrical conductivity of the PEO/PEDOT:PSS NFs. The thermal treatment was optimized to crosslink PEO and PSS while preserving the nanostructuration, to optimize the mechanical coupling with PDMS substrate and to improve water resistance. In this work, we demonstrate excellent mechanical sensing of the NFs Flex Sensor coupled to electrochemical pH detection. Change of pH was detected by Electrochemical Impedance Spectroscopy (EIS), obtaining a linear dependence of the capacitance with the pH value. The piezo-resistive caracterization of the Crosslinked NFs Flex Sensors demonstrated the ability of nanomaterials to recover their initial configuration after release of the mechanical strain in both compression and traction mode. The Gauge Factors (GFs) values were 45.84 in traction and 208.55 in compression mode, reflecting the extraordinary piezoresistive behavior of our nanostructurated PEO/PEDOT:PSS NFs. REFERENCES [1] H. S. P. W. Weng, P.N. Chen, S.S. He, X.M. Sun, Chem. Int. Ed 2016, 55, 6140; [2] W. Zeng, L. Shu, Q. Li, S. Chen, F. Wang, X. M. Tao, Adv. Mater. 2014, 26, 5310; [3] Y. Liu, H. Wang, W. Zhao, M. Zhang, H. Qin, Y. Xie, Sensors, 2018, 18, 645.
Highlights
Flex sensors are composed of a flexible substrate (PDMS, textile, Kapton) and a sensitive element that can be made of nanomaterials, intrinsically conductive polymers, conductive inks or optical fiber. [4,5,6,7,8] devices able to give information on the mechanical strain and on the physiological parameters are attracting interest to extend the application field to health monitoring devices, designing novel, robust and low-cost wearable sensing units [9,10,11,12]
The application of polyethylene oxide (PEO)/PEDOT:PSS Crosslinked Nanofibers (NFs) as common sensitive element for flex sensing coupled with pH sensing in human body joint monitoring was investigated
The great novelty of this device is based on the use of the same sensitive material for both the sensing units, allowing to significantly simplify the whole process flow to fabricate the final platform. This result is possible since PEO/PEDOT:PSS Crosslinked NFs are able to transduce both the two signals by exploiting their different properties
Summary
Flexible and wearable devices able to sense bending are more and more developed for application like smart clothing, rehabilitation, prosthetic limbs, sport and research.[1,2,3] Usually, flex sensors are composed of a flexible substrate (PDMS, textile, Kapton) and a sensitive element that can be made of nanomaterials, intrinsically conductive polymers, conductive inks or optical fiber. [4,5,6,7,8] devices able to give information on the mechanical strain and on the physiological parameters are attracting interest to extend the application field to health monitoring devices, designing novel, robust and low-cost wearable sensing units [9,10,11,12]. Proceedings 2020, 4, x FOR PEER REVIEW for these fields of application since it is directly related to the health state of the body (cystic fibrosis, dehydration, diabetes, cancer, etc.) and to the physical activity.[13,14,15] two-sensing units on one single device often requires long and complicated fabrication process-flows, unless if the same sensitive material is used for the two units.. The extraordinary elastic behaviour of the PDMS slab ensures optimal transfer of the mechanical deformation from the joint to the sensing nanofibers. This excellent behaviour is directly reflected in the large values of the Gauge Factors (GFs) which are 45.84 and 208.55 in traction and compression mode, respectively
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
