Cu–Ag core–shell nanowires for electronic skin with a petal molded microstructure

Abstract

Flexible electronic skin (e-skin) have been widely researched due to their potential applications in wearable electronics, robotic systems, biomedicines, et al. For realization of lower cost of the e-skin, copper nanowires (CuNWs) are often served as conductive fillers since their high conductivity and flexibility. However, CuNWs are very sensitive to oxygen that greatly hinders their developments. To solve this issue, a facile galvanic replacement reaction without any heating, stirring or dispersant was performed to coat a thin layer of silver (20 nm) on the surface of CuNWs and Cu-Ag core-shell nanowires (Cu-Ag NWs) with excellent oxidation resistance were obtained and served as conductive fillers for e-skin. To further increase the sensitivity and reduce the response time and detection limit, micro-structure of the surface of rose petal was replicated and introduced onto 2D polydimethylsiloxane (PDMS) surface. The bio-inspired piezoresistive e-skin demonstrates high sensitivity (1.35 kPa -1 ), very low detection limit (< 2 Pa), very low response time and relaxation time (36 ms and 30 ms) and outstanding working stability (more than 5000 cycles). The high performance e-skin has extensive applications in voice recognition, wrist pulses monitoring and detection of spatial distribution of pressure.−1 ), fast response (<500 ms) and low detection limit (20 mg). 29 Wang, et al. replicated the surface of silk and constructed a piezoresistive e-skin, which can be used as voice The defining feature of our design is that the length of the CuNWs should not larger than 20 μm. Therefore, a lower EDA concentration (95 mM) and shorter reaction time (<1.0 h) was performed to synthesis shorter CuNWs. Fig.1a and b show the

Light‐Boosting Highly Sensitive Pressure Sensors Based on Bioinspired Multiscale Surface Structures

“…Hereinto, one universal strategy is to introduce structured surfaces on active conductive layers4,16,18,19 and/or flexible elastomeric substrates1,14,20,21 of the assembled pressure sensors. During loading/unloading the external pressure, the changes in conductive path/area and thus the changes in corresponding current/resistance will be augmented enormously in the structured case, compared with nonstructured one.…”

Nanowire Genome: A Magic Toolbox for 1D Nanostructures

“…Meanwhile, many factors including temperature changes and the related ion concentrations can affect the actual value of the reduction potential, which eventually affects the occurrence of a galvanic replacement reaction. A series of 2G Ag‐capped Cu NWs with different morphologies were synthesized by controlling the reaction parameters . For example, with a low concentration of Ag + (Cu/Ag molar ratio of 5:1), Ag NPs with an average diameter of 8.4 nm were deposited onto Cu NWs through the in situ substitutional reactions (Figure b).…”

Copper nanomaterials and assemblies for soft electronics

“…Considering that Ag has a higher reduction potential than Cu, Ag ions can react with Cu to form the Ag layer by the galvanic replacement reaction [147][148][149]. Cu@Ag NPs were obtained by reacting CuNPs obtained in oleylamine with AgNO 3 at a reaction temperature of 80°C (Fig.…”

“…A highly sensitive and stable flexible electronic skin was fabricated with Ag covered CuNWs coated on PDMS with surface structure replicated from a piece of rose petal (Fig. 15e) [148]. Such a microstructure was used for the purpose of reducing the response time and large hysteresis of elas- [170].…”

“…The pressure sensor with high sensitivity (1.35 kPa −1 , Fig. 15f), very low detection limit (<2 Pa), very low response time and relaxation time (36 and 30 ms) and outstanding working stability (more than 5000 cycles) has extensive applications in voice recognition, wrist pulse monitoring and pressure mapping [148]. Other than thin films, CuNWs based porous 3D structures, such as aerogels (Fig.…”