Skin‐Like Stretchable Fuel Cell Based on Gold‐Nanowire‐Impregnated Porous Polymer Scaffolds

Abstract

Such future soft wearable electronics or wearable 2.0 products [8] will not be viable unless efficient reliable and skin-conformal power sources are to be developed. Most of the current wearable electronics are powered by rigid and bulky lithium-ion battery. Although paper batteries are emerging as a thinner version candidate, [9] they are still based on conventional metallic materials, which are neither stretchable nor compressive, unable to conformally be attached onto human skin. Typical smart soft electronics including wearable glucose sensors, pressure sensors, and surface electromyography (sEMG) only require a voltage of <100 mV and a power consumption of <20 µW, which could be supplied by different types of energy devices. [10] In this context, a variety of soft energy devices based on nanomaterials including batteries, [11] supercapacitors, [12,13] solar cells, [14] triboelectric nanogenerators, [15] and fuel cells [16-18] have attracted tremendous attention as the potential replacement of the lithium-ion battery to power skin-like electronics. Each type of those energy devices has their own intrinsic pros and cons. Wearable supercapacitors cannot provide continuous long-term energy supplies; [12,13] the performance of wearable photovoltaic devices is highly dependent on the external light source; [14] and the wearable nanogenerators based on piezoelectric and triboelectric devices can only provide intermittent energy and must be integrated with energy storage devices for continuous long-term monitoring. [15] Stretchable enzymatic biofuel cell that uses glucose or lactic acid in the body fluid to generate energy has been considered as an environmentally friendly power source for the next-generation skin-like energy devices. However, its performance is largely dependent on the stability of the enzyme, which may be easily affected by body temperature, pH, and fuel concentrations. [19,20] In contrast, fuel cells that use ethanol or methanol as a model system could offer a much higher power density and stability as they are not influenced by the biological environments. [21] A number of materials including silver nanowires, [22] carbon fibers, [23] graphene paper, [24] nickel foam, [25] vertically aligned gold nanowires (V-AuNWs) [26] have been demonstrated to fabricate flexible or even stretchable fuel cells. Nevertheless, high power output, skin-like device thickness, Skin-like energy devices can be conformally attached to the human body, which are highly desirable to power soft wearable electronics in the future. Here, a skin-like stretchable fuel cell based on ultrathin gold nanowires (AuNWs) and polymerized high internal phase emulsions (polyHIPEs) scaffolds is demonstrated. The polyHIPEs can offer a high porosity of 80% yet with an overall thickness comparable to human skin. Upon impregnation with electronic inks containing ultrathin (2 nm in diameter) and ultrahigh aspect-ratio (>10 000) gold nanowires, skin-like strain-insensitive stretchable electrodes are successfully fabricated. With such designed ...

Colloidal synthesis of Au nanomaterials with a controlled morphology and crystal phase via the [Au(i)-oleylamine] complex

“…Recently, Au NWs have been developed to serve as stretchable electrodes of exible fuel cells. 143,144 Compared with traditional fuel cells using rigid electrodes, stretchable fuel cells based on Au NW electrodes can be integrated into wearable and implantable electronics.…”

Wearable CNTs-based humidity sensors with high sensitivity and flexibility for real-time multiple respiratory monitoring

“…Recently, many researchers have made great efforts to eliminate this inconvenience, including sensors and ventilation systems with additional filters. However, most of the early wearable sensors added to various accessories have been focused on function and performance rather than user convenience [ 3 , 4 ]. In addition, owing to the lack of batteries, wireless communication technology, and measurement efficiency, these were operated internally via various communication devices, and sensors were also based on existing medical sensors, which caused great inconvenience to users.…”

Flourishing energy harvesters for future body sensor network: from single to multiple energy sources

“…Generally, the available energy sources around us include mechanical energy ( Liu et al, 2013 , 2014 ), solar energy ( Hashemi et al., 2020 ), thermal energy ( Xie et al., 2011 ; Zhang et al., 2019a ), and biochemical energy ( Jeerapan et al., 2020 ). As illustrated in Figure 1 B, there are various conversion mechanisms, including piezoelectric ( Shi et al., 2016a ; Sun et al., 2019a ), triboelectric ( Dong et al., 2021 ; Gunawardhana et al., 2020 ), and electromagnetic effects ( Zhang et al., 2020b ) for mechanical energy harvesting; the photovoltaic effect for solar energy harvesting ( Park et al., 2018 ); the thermoelectric or pyroelectric effect for thermal energy harvesting ( Sun et al., 2019c ; Yang et al., 2012 ); and biofuel cell for biochemical energy harvesting in biofluids ( Gong et al., 2020 ; Zhai et al., 2020 ). These renewable energy harvesters (EHs) have been attracting great attention and hold great promises to realize self-powered wireless sensor networks (WSN) for personal health care and smart home.…”