Soft Electronically Functional Polymeric Composite Materials for a Flexible and Stretchable Digital Future

Abstract

Flexible/stretchable electronic devices and systems are attracting great attention because they can have important applications in many areas, such as artificial intelligent (AI) robotics, brain-machine interfaces, medical devices, structural and environmental monitoring, and healthcare. In addition to the electronic performance, the electronic devices and systems should be mechanically flexible or even stretchable. Traditional electronic materials including metals and semiconductors usually have poor mechanical flexibility and very limited elasticity. Three main strategies are adopted for the development of flexible/stretchable electronic materials. One is to use organic or polymeric materials. These materials are flexible, and their elasticity can be improved through chemical modification or composition formation with plasticizers or elastomers. Another strategy is to exploit nanometer-scale materials. Many inorganic materials in nanometer sizes can have high flexibility. They can be stretchable through the composition formation with elastomers. Ionogels can be considered as the third type of materials because they can be stretchable and ionically conductive. This article provides the recent progress of soft functional materials development including intrinsically conductive polymers for flexible/stretchable electrodes, and thermoelectric conversion and polymer composites for large area, flexible stretchable electrodes, and tactile sensors.

Bioinspired Prosthetic Interfaces

“…Meanwhile, the stretchability of conducting polymers could be improved by mixing with soft polymers, molecularly engineering side chains, and adding ionic liquid enhancers . A more thorough and detailed summary of the methods to enable conducting polymers with better conductivity and stretchability can be found in the review by Tee and Ouyang . As an example of merging stretchability and conductivity of polymers, Teo et al developed a highly conductive (S > 1000 S cm −1 ) stretchable electrode based on PEDOT:PSS/ionic liquid, which exhibited small resistance variation at 180% strain ( R / R 0 < 2) .…”

“…[94] A more thorough and detailed summary of the methods to enable conducting polymers with better conductivity and stretchability can be found in the review by Tee and Ouyang. [95] As an example of merging stretchability and conductivity of polymers, Teo et al developed a highly conductive (S > 1000 S cm −1 ) stretchable electrode based on PEDOT:PSS/ ionic liquid, which exhibited small resistance variation at 180% strain (R/R 0 < 2). [96] Furthermore, by rationally selecting stretchability and electrical conductivity (STEC) enhancers, Wang et al developed the PEDOT:PSS conductors with superior conductivity and stretchability (3100 S cm −1 at 0% strain, 4100 S cm −1 at 100% strain, and 100 S cm −1 at 600% strain), showing great promise for stretchable electronics.…”

A Platform to Study the Effects of Electrical Stimulation on Immune Cell Activation During Wound Healing

“…[21] The traces were insulated by attaching a Teflon tape on top, with vias in the tape having been cut by a laser-cutter. [3] and shown in Figure 2D Both screen-printed and inkjet-printed electrodes were covered with a conducting polymer poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) to provide a stable, biocompatible interface, [20,[36][37][38][39] to further lower the impedance at the electrode-skin interface, and to provide a greater charge injection capacity for ES than metal surfaces. We demonstrated the capability of these arrays to map areas of varying impedance, as found in wound areas which would have lower impedance in regions with damaged skin compared to undamaged skin.…”

“…Biosys. 2019, 3,1900106 Both screen-printed and inkjet-printed electrodes were covered with a conducting polymer poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) to provide a stable, biocompatible interface, [20,[36][37][38][39] to further lower the impedance at the electrode-skin interface, and to provide a greater charge injection capacity for ES than metal surfaces. [22,23] As shown in Figure S2, Supporting Information, the electrodes without PEDOT:PSS coated on the ends exhibited a reduction in current supplied over time, reducing from 300 µA to less than 10 µA current after 40 min, while the PEDOT:PSS-coated electrodes maintained the current magnitude for the full 1 h stimulation time.…”

Copper nanomaterials and assemblies for soft electronics

“…Indium tin oxide (ITO) has been used as the transparent conductors in most devices due to its high conductivity and transmittance. However, the major limitations of ITO for the use in next-generation soft electronics are its brittleness, scarcity and rising costs [49,70,157]. Due to the flexibility of copper nanomaterials, especially CuNWs, their thin films are the potential candidates to replace ITO in various optical electronics [49,60,158] (Table S2).…”