Elastocaloric Kirigami Temperature Modulator

Hirai, Takamasa; Iguchi, Ryo; Miura, Ai; Uchida, Kenichi

doi:10.1002/adfm.202201116

Cited by 8 publications

(20 citation statements)

References 54 publications

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“…To improve the perspective of elastocaloric kirigami temperature modulators, it is important to uncover materials with large elastocaloric performance in the region of elastic deformation because, in that region, the performance at a focused cooling/heating source in a kirigami-patterned sheet directly depends on the performance in the unpatterned sheet. Note that the magnitude of the elastocaloric temperature modulation normalized by the stress in the unpatterned PS sheet is ∼1.5 × 10 −8 K Pa −1 , which realizes the local temperature change of 0.4 K at typical positions by applying uniaxial strain (stress) of 1.0% (4.0 MPa) in the kirigami-patterned PS sheet [25].…”

Section: Introductionmentioning

confidence: 62%

“…Finally, the thermal images recorded were transformed into the lock-in amplitude A (>0) and phase ϕ (0 • ⩽ ϕ < 360 • ) images through Fourier analysis, in which A informs the magnitude of the elastocaloric temperature modulation and ϕ the sign of the temperature modulation as well as the time delay due to the thermal diffusion. In previous study, it was shown that the value of ϕ due to the elastocaloric effect in unpatterned plastic sheets at 1 Hz is nearly 180 • and the contribution of thermal diffusion is negligible [25]. Unless otherwise specified, the integration time of each LIT measurement t int is 60 s. The performance of the elastocaloric temperature modulation was thus quantified by |∆T|/∆σ, where ∆T is the elastocaloric temperature change calculated as ∆T = Acosϕ and ∆σ is the stress for stretching the sample, calculated as ∆σ = ∆F/wt with ∆F being the change in the load monitored using the load cell.…”

Section: Lit Measurement Of Elastocaloric Effectmentioning

confidence: 95%

“…The temperature modulation generated by the elastocaloric effect was measured using the LIT technique [37]. In the LIT measurement, we recorded thermal images of a sample surface by applying a periodic oscillation of the input signal using an infrared camera and extracted a temperature change oscillating with the same frequency f as the input frequency [25,[38][39][40][41][42] (figure 2). Since the LIT method enables contact-free temperature measurements with high temperature and spatial resolutions and separation of the temperature change due to a target effect and a background signal, it is suitable to measure the elastocaloric temperature change in the small strain regime, compared with other methods for measuring the caloric effects [39].…”

Section: Lit Measurement Of Elastocaloric Effectmentioning

confidence: 99%

“…Recently, a different approach to manipulate the magnitude and distribution of the elastocaloric temperature change has been proposed and demonstrated based on the 'kirigami' processing, inspired by the art of paper cutting [25]. A programmable cutting pattern on a solid sheet artificially introduces a non-uniform spatial distribution of the internal stress against the application of uniaxial strain, generating focused elastocaloric heating and cooling sources at designed positions.…”

Section: Introductionmentioning

confidence: 99%

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Elastocaloric effect of shape memory polymers in elastic response regime

et al. 2023

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The solid-state cooling/heating technology based on the elastocaloric effect is one of the promising alternatives to vapor compression systems. The large elastocaloric temperature modulation is often generated through the non-linear strain-induced structural transition by applying large strain and/or stress to ferroelastic materials. Recently, an unconventional approach to expand the application possibilities of the elastocaloric effect was demonstrated by processing elastocaloric materials into kirigami structures, which was inspired by the art of paper cutting. By using this approach, only a small stretch of processed conventional plastics can locally provide more efficient performance of elastocaloric temperature modulation than that of ferroelastic materials. To further improve such a unique functionality, it is necessary to find plastic or polymeric materials showing large elastocaloric effects in the linear elastic response regime that can be driven by a MPa-order weak stress application, where the non-linear structural transition is irrelevant. In this work, by means of recently developed measurement technique for the elastocaloric effect based on the lock-in thermography, we found that shape memory polymers (SMPs) show prominent performance of the elastocaloric temperature modulation that is larger than conventional plastics. SMPs enable the control of the crystallinity by changing the cross-linking agents, melting temperature by changing the degree of polymerization, and orientation of the polymer chain segment by the shape memory effect. By utilizing the unique properties of SMPs, we manipulated their elastocaloric performance. The experimental results reported here will highlight the potential of smart polymers for flexible and durable elastocaloric applications.

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Section: Introductionmentioning

confidence: 62%

Section: Lit Measurement Of Elastocaloric Effectmentioning

confidence: 95%

Section: Lit Measurement Of Elastocaloric Effectmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Elastocaloric effect of shape memory polymers in elastic response regime

et al. 2023

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“…It is usually claimed that inducing mechanocaloric effects by the application of non-uniform stresses is more efficient than by the application of uniform stresses since a lower driving force is required to induce a large caloric response [7,8]. Nevertheless, the quantitative comparison of uniform and non-uniform effects is not straightforward due to, precisely, the non-uniform character of both stress and strain in the non-uniform case.…”

Section: Introductionmentioning

confidence: 99%

Caloric Effects Induced by Uniform and Non-uniform Stress in Shape-Memory Materials

Porta

Castán

Saxena

et al. 2023

Shap. Mem. Superelasticity

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A Ginzburg–Landau model is developed that is adequate to describe a square-to-rectangle martensitic transition with associated shape-memory and superelastic properties. Using this model we study caloric effects in the vicinity of the martensitic transition induced by stress and we compare the case of a uniform uniaxial stress and the case of a non-uniform continuous distribution of stresses that produce bending of the material. The former case corresponds to an elastocaloric effect and the latter corresponds to a flexocaloric effect. The aim of the work is to quantitatively compare both cases, which we show must be accomplished in terms of equal amounts of exchanged mechanical work. It is then obtained that the flexocaloric effect is more efficient for low exchanged work but less efficient for large exchanged work.

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Enhancement of Transverse Thermoelectric Conversion by Interface‐Induced Spin Current in Ferromagnetic Metal/Nonmagnetic Insulator Hybrid‐Structure

Itoh,

Kozuka,

Hirai

et al. 2024

Adv Funct Materials

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Transverse thermoelectric conversion phenomena including the anomalous Ettingshausen effect (AEE) and anomalous Nernst effect (ANE) in magnetic materials are actively investigated to realize versatile cooling and energy harvesting technologies. However, further improvement of the thermoelectric performance of AEE and ANE is still required, and most research efforts have focused on material exploration. Here, a new approach to improve the transverse thermoelectric conversion performance through interface engineering is reported by focusing on the transverse thermoelectric phenomena that output heat currents. A longitudinal charge current in a ferromagnetic metal Ni/nonmagnetic insulator Bi2WO6 hybrid‐structure induces a larger transverse heat current than that of AEE in a Ni single‐layer. It is indicated that the enhancement of the transverse thermoelectric conversion is due to the generation of a heat current concomitant with a spin current induced at the Ni/Bi2WO6 interface. This finding demonstrates that the interface of a magnetic metal/nonmagnetic insulator has a potential to improve the transverse thermoelectric performance, extending the applicability of nonmagnetic insulators to the field of spin caloritronics and thermoelectrics.

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Elastocaloric Kirigami Temperature Modulator

Cited by 8 publications

References 54 publications

Elastocaloric effect of shape memory polymers in elastic response regime

Elastocaloric effect of shape memory polymers in elastic response regime

Caloric Effects Induced by Uniform and Non-uniform Stress in Shape-Memory Materials

Enhancement of Transverse Thermoelectric Conversion by Interface‐Induced Spin Current in Ferromagnetic Metal/Nonmagnetic Insulator Hybrid‐Structure

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