Beyond Chemistry: Tailoring Stiffness and Microarchitecture to Engineer Highly Sensitive Biphasic Elastomeric Piezoresistive Sensors

Abstract

Carbon-based nanoparticles and conductive polymers are two classes of materials widely used in the production of three-dimensional (3D) piezoresistive sensors. One conductive polymer, poly­(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) has excellent stability and conductivity yet is limited in its application as a sensor, often existing upon a base, limiting its performance and potential. Despite much progress in the field of materials chemistry and polymer synthesis, one aspect we consider worthy of exploration is the impact that microstructure and stiffness may have on the sensitivity of 3D sensors. In this study, we report a strategy for fabricating biphasic electroactive sponges (EAS) that combine 3D porous PEDOT:PSS scaffolds possessing either an isotropic or anisotropic microarchitecture, infused with insulating elastomeric fillers of varying stiffness. When characterizing the electromechanical behavior of these EAS, a higher stiffness yields a higher strain gauge factor, with values as high as 387 for an isotropic microarchitecture infused with a stiff elastomer. The approach we describe is cost-effective and extremely versatile, by which one can fabricate piezoresistive sensors with adaptable sensitivity ranges and excellent high strain gauge factor with the underlying microarchitecture and insulant stiffness dictating this performance.

Hydroxyapatite-filled osteoinductive and piezoelectric nanofibers for bone tissue engineering

“…pulse/respiration monitoring, drug delivery monitoring) and human motion detection, or as components of pressure sensors for detection of subtle pressures (e.g. blood flow) [ 68 , 69 ]. A number of studies have reported the use of PVDF and PVDF-TrFE in the development of piezoresistive sensors with potential applications in TE [ 70–72 ].…”

A Workflow to Produce a Low-Cost In Vitro Platform for the Electric-Field Pacing of Cellularised 3D Porous Scaffolds

“…Isotropic scaffolds were produced using standard cell culture multiwell plates, while a custom-made mold containing a bottom stainless-steel layer and a top polydimethylsiloxane (PDMS) (SYLGARD 184, Farnell, Ireland) was fabricated to induce ice crystal alignment by virtue of the different thermal conductivities of the two materials, ultimately resulting in anisotropic scaffolds. 28 Freezing was performed at −40 °C for 1 h, after which the temperature was raised to −10 °C at a rate of 1 °C per minute, held for 18 h at a vacuumed environment PEDOT:PSS-GOPS scaffolds underwent annealing treatment in a vacuum oven at 140 °C for 1 h and were crystallized as previously reported. 27 Briefly, PEDOT:PSS-GOPS samples, with both isotropic and anisotropic architecture, were submerged into a bath of 100% sulfuric acid for 15 min, then washed multiple times using deionized water.…”

“…Porous 3D sponge-like scaffolds were created through lyophilization using a freeze-dryer (FreeZone, Labconco Corporation, USA). Isotropic scaffolds were produced using standard cell culture multiwell plates, while a custom-made mold containing a bottom stainless-steel layer and a top polydimethylsiloxane (PDMS) (SYLGARD 184, Farnell, Ireland) was fabricated to induce ice crystal alignment by virtue of the different thermal conductivities of the two materials, ultimately resulting in anisotropic scaffolds . Freezing was performed at −40 °C for 1 h, after which the temperature was raised to −10 °C at a rate of 1 °C per minute, held for 18 h at a vacuumed environment of 0.2 mbar, ramped to 20 °C at a rate of 1 °C per minute, and finally held for 2 h.…”

A guide to the manufacture of sustainable, ready to use in vitro platforms for the electric-field pacing of cellularised 3D porous scaffolds

“…Porous 3D sponge-like scaffolds were created through lyophilisation using a freeze-dryer (FreeZone, Labconco Corporation, USA). Isotropic scaffolds were produced using standard cell culture multi-well plates, while a custom-made mould containing a bottom stainless-steel layer and a top PDMS (SYLGARD® 184, Farnell, Ireland) was fabricated to induce ice crystal alignment by virtue of the different thermal conductivities of the two materials 27 . Freezing was performed at -40 °C, for 1 hour after which the temperature raised to -10 °C at a rate of 1 °C per minute, held for 18 hours at a vacuumed environment of 0.2 mbar, ramped to 20 °C at a rate of 1 °C per minute, and finally held for 2 hours.…”