A Nature‐Inspired, Flexible Substrate Strategy for Future Wearable Electronics

Abstract

Flexibility plays a vital role in wearable electronics. Repeated bending often leads to the dramatic decrease of conductivity because of the numerous microcracks formed in the metal coating layer, which is undesirable for flexible conductors. Herein, conductive textile‐based tactile sensors and metal‐coated polyurethane sponge‐based bending sensors with superior flexibility for monitoring human touch and arm motions are proposed, respectively. Tannic acid, a traditional mordant, is introduced to attach to various flexible substrates, providing a perfect platform for catalyst absorbing and subsequent electroless deposition (ELD). By understanding the nucleation, growth, and structure of electroless metal deposits, the surface morphology of metal nanoparticles can be controlled in nanoscale with simple variation of the plating time. When the electroless plating time is 20 min, the normalized resistance (R/R0) of as‐made conductive fibers is only 1.6, which is much lower than a 60 min ELD sample at the same conditions (R/R0 ≈ 5). This is because a large number of unfilled gaps between nanoparticles prevent metal films from cracking under bending. Importantly, the Kelvin problem is relevant to deposited conductive coatings because metallic cells have a honeycomb‐like structure, which is a rationale to explain the relationships of conductivity and flexibility.

3D Shapeable, Superior Electrically Conductive Cellulose Nanofibers/Ti 3 C 2 T x MXene Aerogels/Epoxy Nanocomposites for Promising EMI Shielding

“…In Figure 2(a), the (002) diffraction peak shifts from 9.7°for Ti 3 AlC 2 to 6.2°for Ti 3 C 2 T x , indicating that the corresponding interlayer spacing 2 Research is enlarged from 1.10 to 1.42 nm, due to the removal of Al atomic layers, proving the successful synthesis of Ti 3 C 2 T x nanosheets [37,38]. In the wide-scan XPS spectra ( Figure S1(b)), the Al 2s and Al 2p peaks of Ti 3 AlC 2 disappear after etching, while the new peaks of O 1s and F 1s are observed in Ti 3 C 2 T x [39], confirming the complete removal of Al atomic layer and the formation of -OH and -F groups on the surface of Ti 3 C 2 T x nanosheets. In Figure S1(d), the absorption peaks at 3460, 1630, and 600 cm -1 of Ti 3 C 2 T x nanosheets are ascribed to the stretching vibration from -OH, C=O, and Ti-O groups, respectively [40,41].…”

Smart textiles and wearable technologies – opportunities offered in the fight against pandemics in relation to current COVID-19 state

“…Having all the challenges in the head of us the optimal outcome is to emerge from the current crisis with a clearer vision of how to deploy telemedicine to achieve its benefits while avoiding or minimizing potential abuse and exploitation [147]. Smart or e-textiles start to include natural fabrics and become sensors of human body temperature, sweat, or breathing [155] or bending able to monitor human touch [156]. As the strain sensors can be incorporated in smart garment parts, it can be a part of face masks too, together with other biosensing capabilities for detecting viruses.…”

Ultraelastic Yarns from Curcumin‐Assisted ELD toward Wearable Human–Machine Interface Textiles

“…Some other approaches offered alternatives to deal with these issues via doping dopamine and tannic acid to facilitate highly conductive and durable textiles. [42][43][44] Nevertheless, it is less feasible in practical applications because the dopamine is expensive and tannic acid is unstable in aqueous solution during long-term storage due to the macromolecular aggregation and self-precipitation. The attempts are still ongoing for achieving high-quality and ultralight textile-based sensors for wearable HMIs.…”