Strong and Highly Conductive Poly(vinyl alcohol)/Carbon Dot/EGaIn Composite Films for Flexible and Transient Electronics

Abstract

Composite films with comprehensive high tensile strength, great electrical conductivity, and excellent degradable property meet the requirement to serve as flexible and transient electronics; however, integrating these properties together remains to be achieved. In this work, poly­(vinyl alcohol) (PVA)–carbon dot (CCD)–EGaIn composite films combining these admirable properties were prepared using nontoxic raw materials and facile cast-dropping methods. In the obtained PVA–CCD–EGaIn composite films, CCD acted as a physical cross-linker to improve the mechanical properties due to the H-bond interactions between PVA and CCD, contributing to an improved tensile strength of 65.0 MPa (relative variation of 22.2%) and a high tensile modulus of 2.24 GPa (relative variation of 96.5%). EGaIn acted as a conductive additive to endow the composite film with a high electrical conductivity (5.35 S/m). The resultant PVA–CCD–EGaIn composite films also demonstrated preferable thermal stability and advantageous photothermal conversion behavior. Moreover, the electrical conductivity of composite films was stable under repeated bending–unbending tests, allowing for the real-time detection of human activities. Interestingly, the composite films were also degradable in a HCl solution (pH = 5), which was an attractive feature for the emerging transient electronics. This work provides a workable guideline for the fabrication of green and economical multifunctional composite materials.

Neuromodulation of the peripheral nervous system: Bioelectronic technology and prospective developments

“…[190][191][192] For instance, gallium-based LMs, such as Galinstan or eutectic gallium indium alloy (EGaIn), have not only a low modulus (204 kPa) but also excellent electrical conductivity (3.4 MS m −1 ), making them ideal candidates for neuromodulation applications. [193][194][195][196][197][198][199][200][201][202][203] One of the key advantages of utilizing LM in bioelectronics applications pertains to its facile patterning method. The inherent softness of LM enables the creation of intricate 2D or 3D patterns even on flexible and curved surfaces such as human skin (Figure 7a).…”

“…In developing materials that allow for soft interfaces, one promising area is the field of liquid metals (LMs) [190–192] . For instance, gallium‐based LMs, such as Galinstan or eutectic gallium indium alloy (EGaIn), have not only a low modulus (204 kPa) but also excellent electrical conductivity (3.4 MS m −1 ), making them ideal candidates for neuromodulation applications [193–203] . One of the key advantages of utilizing LM in bioelectronics applications pertains to its facile patterning method.…”

Current Status and Outlook of Low‐Melting‐Point Metals in Biomedical Applications

“…[141] Additionally, with numerous research surfaces, these EGaIn composite-based sensors can be applied in applications such as soft robotics, stretchable electronics, electronic skin, and wearable devices. [140][141][142][143]146,147] Won et al embedded EGaIn into soft polymers to form liquid metal-embedded elastomers that exhibited excellent electrical properties. [148] The composites that were printed with 80% EGaIn volume fraction demonstrated a volumetric electrical conductivity of 5 × 10 4 S cm −1 (Figure 5c).…”

“…[ 141 ] Additionally, with numerous research surfaces, these EGaIn composite‐based sensors can be applied in applications such as soft robotics, stretchable electronics, electronic skin, and wearable devices. [ 140‐143,146,147 ] Won et al. embedded EGaIn into soft polymers to form liquid metal‐embedded elastomers that exhibited excellent electrical properties.…”

Smart Eutectic Gallium–Indium: From Properties to Applications

“…These properties make it possible to measure molecular layer properties by preparing EGaIn tips or using it in microfluidic channels, [8,11] to prepare sensors, antennas, electronic circuits, and other flexible electronic devices. [12][13][14][15][16][17][18][19][20][21][22] Furthermore, EGaIn can be used for heat management devices, motors, generators, batteries, and other energy devices, [23][24][25][26][27][28][29][30][31] or for catalysts to improve catalytic performance. [32][33][34][35] In addition, EGaIn can also be used in biomedical sciences [36][37][38][39][40][41][42] for drug delivery, tumor therapy, bioimaging, and neural interfaces, and it also plays an important role in other fields.…”