Self-Powered Infrared-Responsive Electronic Skin Employing Piezoelectric Nanofiber Nanocomposites Driven by Microphase Transition

Abstract

Infrared light (IR) detection principles limited by poor photoresponsivity and sparse photogenerated carrier make them impossible to directly applied in flexible IR sensing field attributed to low π−π conjugation effect, thick P− N junction, and harsh band gap, of which IR self-powered electronic skin (e-skin) strongly relies on the essential property of exotic photosensitive-exciting materials, hardly any flexible organic polymer or nanocomposites. Here, an innovative IR selfpowered principle is reported that outstanding piezoelectric effect of poly(vinylidene fluoride) nanofibers (PVDF NFs) is driven by microcrystals' volume expansion caused by the solid−solid phase transition of PVDF/multiwalled carbon nanotubes (MWCNTs)/highly elastic phase change polymer (HEPCP) (PMH) nanocomposites due to MWCNT's excellent IR photoabsorption and thermal conversion capabilities. A flexible IR-sensitive nanocomposite is successfully developed employing PVDF/HEPCP NFs as the framework of a three-dimensional network structure wrapped by the MWCNT/HEPCP nanocomposite. The 33, 50, and 60 wt % PMH nanocomposites are demonstrated cyclic, IR-regulated on/off piezoelectric sensitivity of 889.7, 977.6, and 493.8 mV/(mW•mm −2 ) at IR powers of 5.3 mW/mm 2 , respectively. Furthermore, IR self-powered e-skin has been developed successfully and realized an accurate IR stimulus-sensing location due to the sensitivity, which depends on the size of the sensing area. This innovative strategy provides a new route to the fundamental science and applications of flexible IR self-powered devices, such as e-skin, artificial vision, soft robots, active surveillance sensors, etc.

Recent progress in self‐powered multifunctional e‐skin for advanced applications

“…On the contrary, the right amount of infrared radiation can promote the local microcirculation of the human body, can strengthen the metabolism of lactic acid, Reproduced with permission. [68] Copyright 2020, American Chemical Society increase the nutritional metabolism of muscle. [66] Therefore, efficient and accurate real-time monitoring of solar intensity has become one of the most important characteristics of eskin, among which, the e-skin that can use the photovoltaic effect to self-powered light intensity detection is more popular among people.…”

“…Li et al prepared an infrared sensor based on this principle. [68] The schematic plot and optical photo of the infrared sensor can be seen in Figure 3E. Figure 3F shows the melting and recrystallization of microcrystals in the material under IR irradiation or after IR removal.…”

Exploring Next‐Generation Functional Organic Phase Change Composites

“…[84] In addition to infrared sensing applications, multifunctional, self-regulatory, and self-powder-sensitive PCMs for more diverse application scenarios such as biosensors, electronic skin, and human-machine interfaces have been reported. [85][86][87] In terms of shape memory function, a common thermotriggered shape memory PCM contains different components with distinctive physicochemical and structural properties. Photoabsorption and electrically conductive materials can be employed to induce light-to-thermal and electro-to-thermal energy conversions, respectively, further achieving heat-actuated shape-memory performance (Figure 4c,d).…”

“…[ 84 ] In addition to infrared sensing applications, multifunctional, self‐regulatory, and self‐powder‐sensitive PCMs for more diverse application scenarios such as biosensors, electronic skin, and human–machine interfaces have been reported. [ 85–87 ]…”

Reprocessable, Photothermal Phase Change Material-Based Hybrid Polymeric Networks for Solar-to-Thermal Energy Storage

“…To address the leakage issue of solid–liquid PCMs, form-stable and polymeric solid–solid PCMs have been fabricated via several strategies, such as microencapsulation, physical adsorption, and chemical crosslinking. − Compared to form-stable PCMs with physical interaction, the polymeric solid–solid PCMs could be synthesized by introducing original solid–liquid phase change constituents into the crosslinking network through covalent bonds, which not only obtains the intrinsic ability of anti-leakage but also has high mechanical strength. , Polyethylene glycol (PEG) is considered to be an ideal choice for constructing polymeric solid–solid PCM networks because PEGs have advantages on high latent heat (Δ H ), end-reactive ability, flexible phase transition temperature, good biocompatibility, etc . Therefore, PEG-based polymeric PCM networks have attracted the attention of researchers. , For example, Kong et al synthesized a series of PEG-based PCM networks with modified polycarbonate diol as the curing agent, and they possessed the Δ H of 110 J/g and high thermal stability .…”