Design and Construction of Deformable Heaters: Materials, Structure, and Applications

Abstract

The technological evolution presents us with infinite possibilities of deformable electronics, far beyond what is possible with conventional electronics. [9][10][11][12] For the past few years, heaters' development has grown rapidly due to wearable electronics' advances and the growing need for practical medical requirements. [13][14][15] The advantages of heaters, such as lightweight, good heating stability, and flexibility, make heaters generally a better choice than conventional heating elements. Various heaters applications have been reported, including deicing devices [16][17][18][19][20] , thermal management devices [21][22][23][24][25] , healthcare [26][27][28][29] , wearable sensors [30][31][32] , etc. For instance, heaters can provide the warmth required to extend the operating temperature of liquid crystal displays (LCDs) in cold environments or can increase the temperature for antifogging systems, anti-icing, deicing of optics, or optical displays [33,34] .Conventional rigid heaters are usually using semiconductor or metallic materials as the heating elements, which have demonstrated stable and excellent performance. For example, Rao and co-workers [35] fabricated a transparent heater by physically depositing Au on a quartz substrate and using an acrylic resin as a crack sacrificial template. It is a transparent conductor with a low sheet resistance of 5.4 Ω sq −1 and a high-temperature heater that can reach ≈600 °C within 38 s by applying a voltage of 15 V. However, the heater is restricted in many applications with portable needs, such as human motion detection, wearable electronics, etc., due to the rigid and thick quartz substrate.As shown in Figure 1a, conventional heaters always consist of a heating element and rigid substrate, and the working principle of electrical heaters is based on the Joule effect and thermal diffusion. However, inherently rigid substrate limits the applications of conventional heaters [36] . Flexible and stretchable heaters had gained tremendous attention with the advances of soft electronics. [37][38][39] Flexible heaters can adapt to moderate deformation, such as bending and twisting. [40,41] And stretchable heaters have more application scenarios due to their stretchable characteristics. [42,43] In the last few years, deformable heaters have gained rapid development due to their wide strain range, good repeatability and low density. [44] Figure 1b shows different structure designs of deformable heaters. One of the most significant advantages Conventional heaters have evolved from traditional rigid heaters to flexible heaters, stretchable heaters, and deformable heaters for the development of soft electronics. Film-based or filament-based heaters can be designed and engineered to fulfill the deformable, adaptable and stretchable applications. Compared with conventional heaters, deformable heaters can maintain stable electrothermal property even with large deformation. Based on this, deformable heaters have shown great potential to be used in the field of Internet of Thin...

Stretchable One-Dimensional Conductors for Wearable Applications

“…Electroactive materials capable of converting electrical to thermal energy demonstrate tremendous potential for heating components in wearable textiles. 224 They are helpful for wearable applications, such as thermal therapy, when affixed to the human body. Among electroactive materials, PEDOT/PSS conductive polymer fibers are very promising for these applications because of their tunable electrical conductivity.…”

“…Electroactive materials capable of converting electrical to thermal energy demonstrate tremendous potential for heating components in wearable textiles . They are helpful for wearable applications, such as thermal therapy, when affixed to the human body.…”

Stretchable Composite Conductive Fibers for Wearables

“…Besides, wearable heaters play an important role in keeping warm and hyperthermia, which has also been demonstrated in SCCFs. [310] Wang et al developed highly conductive MXene@aramid nanofibers with unique skin-core structures through wet spinning. [311] The fiber exhibited sensitive electrothermal properties (≈10 s) within 25-123 °C.…”

Thermal Manipulation in Multi‐Layered Anisotropic Materials via Computed Thermal Patterning

“…Highly anisotropic materials have been widely reported, such as cellulose composite, [33] graphene nanocomposites, [34,35] and aligned carbon nanotube film. [36,37] In addition, the cheaper and more common materials, such as nickel-chromium alloy, [38] can be manufactured to the mesoscopic or macroscopic stripshaped structure that can also achieve the oriented thermal beams.…”