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

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.

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Deposition of Bead Arrays With Variable Diameter by Self-Focusing of Electrohydrodynamic Jets

Volume 2: Additive Manufacturing; Materials ◽

10.1115/msec2017-2893 ◽

2017 ◽

Author(s):

Nicolas Martinez-Prieto ◽

Gabriela Fratta ◽

Jian Cao ◽

Kornel Ehmann

Keyword(s):

Low Cost ◽

Three Dimensional ◽

Deposition Process ◽

Direct Writing ◽

Variable Diameter ◽

Self Focusing ◽

Poly Ethylene Oxide ◽

Poly Ethylene ◽

Number Of Passes ◽

Bead Arrays

Electrohydrodynamic processes were used for direct-writing of bead arrays with controllable bead sizes. Experiments were conducted to align layers of bead-on-string structures in an effort to create three-dimensional patterns. The results show that the jet focuses on previously deposited droplets allowing for the selective deposition of material over already deposited patterns. Jet attraction to already deposited solutions on the substrate is attributed to the charge transport at the liquid ink-metal collector interface and the dielectric properties of the water/poly(ethylene oxide) solution under an electric field. The deposition process consists of 3 steps: (1) deposition of a layer of bead-on-string structures, (2) addition of extra volume to the beads by subsequent passes of the jet, and (3) evaporation of the solvent resulting in an array of beads with varying sizes. Patterns with up to 20 passes were experimentally obtained. The beads’ height was seen to be independent of the number of passes. The process reported is a simple, fast, and low-cost method for deposition of bead arrays with varying diameters.

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Block copolymer compatibilization driven frustrated crystallization in electrospun nanofibers of polystyrene/poly(ethylene oxide) blends

RSC Advances ◽

10.1039/c8ra02391c ◽

2018 ◽

Vol 8 (32) ◽

pp. 17989-18007 ◽

Cited By ~ 1

Author(s):

Pratick Samanta ◽

Rajiv Srivastava ◽

Bhanu Nandan

Keyword(s):

Block Copolymer ◽

Ethylene Oxide ◽

Electrospun Nanofibers ◽

Crystallization Behaviour ◽

Confined Crystallization ◽

Poly Ethylene Oxide ◽

Poly Ethylene

Confined crystallization behaviour of poly(ethylene oxide) (PEO) was studied in electrospun nanofibers of the phase-separated blends of polystyrene (PS) and PEO compatibilized with polystyrene-block-poly(ethylene oxide) (PS-b-PEO) block copolymer.

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