A comprehensive review on the output voltage/power of wearable thermoelectric generators concerning their geometry and thermoelectric materials

Soleimani, Zohreh; Zoras, Stamatis; Ceranic, Boris; Shahzad, Sally

doi:10.1016/j.nanoen.2021.106325

Cited by 80 publications

(49 citation statements)

References 168 publications

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“…Flexible thermoelectrics (FTEs) could directly convert heat into electricity, and thus can be regarded as an alternative for powering FTEs that is long-lasting, reliable and safe [ 4 ]. The performance of thermoelectric (TE) materials can be evaluated via the TE figure of merit, zT = S 2 σ T/κ, where S represents the Seebeck coefficient, σ is the electrical conductivity, κ is the thermal conductivity, T represents the absolute temperature of the environment, and the term S 2 σ is defined as the power factor, PF [ 5 ]. To date, Bi 2 Te 3 , with a rhombohedral structure and a band gap of 0.15 eV, is the most widely used TE material, since it has the best TE performance at room temperature among all materials.…”

Section: Introductionmentioning

confidence: 99%

A Bi2Te3-Filled Nickel Foam Film with Exceptional Flexibility and Thermoelectric Performance

et al. 2022

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The past decades have witnessed surging demand for wearable electronics, for which thermoelectrics (TEs) are considered a promising self-charging technology, as they are capable of converting skin heat into electricity directly. Bi2Te3 is the most-used TE material at room temperature, due to a high zT of ~1. However, it is different to integrate Bi2Te3 for wearable TEs owing to its intrinsic rigidity. Bi2Te3 could be flexible when made thin enough, but this implies a small electrical and thermal load, thus severely restricting the power output. Herein, we developed a Bi2Te3/nickel foam (NiFoam) composite film through solvothermal deposition of Bi2Te3 nanoplates into porous NiFoam. Due to the mesh structure and ductility of Ni Foam, the film, with a thickness of 160 μm, exhibited a high figure of merit for flexibility, 0.016, connoting higher output. Moreover, the film also revealed a high tensile strength of 12.7 ± 0.04 MPa and a maximum elongation rate of 28.8%. In addition, due to the film’s high electrical conductivity and enhanced Seebeck coefficient, an outstanding power factor of 850 μW m−1 K−2 was achieved, which is among the highest ever reported. A module fabricated with five such n-type legs integrated electrically in series and thermally in parallel showed an output power of 22.8 nW at a temperature gap of 30 K. This work offered a cost-effective avenue for making highly flexible TE films for power supply of wearable electronics by intercalating TE nanoplates into porous and meshed-structure materials.

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Section: Introductionmentioning

confidence: 99%

A Bi2Te3-Filled Nickel Foam Film with Exceptional Flexibility and Thermoelectric Performance

et al. 2022

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“…The WTEG performance is not only dependent on thermoelectric material properties and geometry structure, and also strongly determined by thermal conditions (such as skin temperature and the air-side natural convection) [ 4 , 5 ]. Among these factors, it is crucial to achieving a large temperature difference between the cold/hod sides of the thermoelectric legs for harvesting the body heat [ 6 ]. Thus, the performance of WTEG could be remarkably improved by enhancing the thermal release of its cold side.…”

Section: Introductionmentioning

confidence: 99%

A Liquid Metal-Enhanced Wearable Thermoelectric Generator

Liu¹,

Li²,

Yang³

et al. 2022

Bioengineering

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It is a key challenge to continuously power personal wearable health monitoring systems. This paper reports a novel liquid metal-enhanced wearable thermoelectric generator (LM-WTEG that directly converts body heat into electricity for powering the wearable sensor system. The gallium-based liquid metal alloys with room-temperature melting point (24~30 °C) and high latent heat density (about 500 MJ/m3) are used to design a new flexible finned heat sink, which not only absorbs the heat through the solid-liquid phase change of the LM and enhances the heat release to the ambient air due to its high thermal conduction. The LM finned is integrated with WTEG to present high biaxial flexibility, which could be tightly in contact with the skin. The LM-WTEG could achieve a super high output power density of 275 μW/cm2 for the simulated heat source (37 °C) with the natural convective heat transfer condition. The energy management unit, the multi-parameter sensors (including temperature, humidity, and accelerometer), and Bluetooth module with a total energy consumption of about 65 μW are designed, which are fully powered from LM-WTEG through harvesting body heat.

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“…With the transition of many electronic devices from traditionally rigid to flexible as well as wearable and implantable, the demand for a corresponding power supply, especially those that are autonomous with a long life, is growing. , Thermoelectric (TE) materials that can stably and directly convert ubiquitous heat or industrial waste heat into electric energy have become a hot topic in recent decades, − and especially now for their applicable potential in flexible TE (FTE) devices that can present conformal interactions with heat sources to maximize heat harvesting. − The energy conversion efficiency of TE materials is determined by a dimensionless figure of merit ZT ( ZT = S 2 σTκ –1 ), where S is the Seebeck coefficient, σ is the electrical conductivity, T is the working temperature and κ is the thermal conductivity, respectively. The combined parameter of S 2 σ , called the power factor (PF), is an indicator of the maximum output power .…”

Section: Introductionmentioning

confidence: 99%

Flexible n-Type Abundant Chalcopyrite/PEDOT:PSS/Graphene Hybrid Film for Thermoelectric Device Utilizing Low-Grade Heat

Wang

Pang

Guo

et al. 2021

ACS Appl. Mater. Interfaces

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Combining inorganic thermoelectric (TE) materials with conductive polymers is one promising strategy to develop flexible thermoelectric (FTE) films and devices. As most inorganic materials tried up until now in FTE composites are composed of scarce or toxic elements, and n-type FTE materials are particularly desired, we combined the abundant, inexpensive, nontoxic Zndoped chalcopyrite (Cu 1−x Zn x FeS 2 , x = 0.01, 0.02, 0.03) with a flexible electrical network constituted by poly(3,4-ethylenedioxythiophene) polystyrenesulfonate (PEDOT:PSS) and graphene for n-type FTE films. Hybrid films from the custom design of binary Cu 1−x Zn x FeS 2 /PEDOT:PSS to the optimum design of ternary Cu 0.98 Zn 0.02 FeS 2 /PEDOT:PSS/graphene are characterized. Compared with the binary film, a 4-fold enhancement in electrical conductivity was observed in the ternary film, leading to a maximum power factor of ∼ 23.7 μW m −1 K −2 . The optimum ternary film could preserve >80% of the electrical conductivity after 2000 bending cycles, exhibiting an exceptional flexibility due to the network constructed by PEDOT:PSS and graphene. A five-leg thermoelectric prototype made of optimum films generated a voltage of 4.8 mV with a ΔT of 13 °C. Such an evolution of an inexpensive chalcopyrite-based hybrid film with outstanding flexibility exhibits the potential for cost-sensitive FTE applications.

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A comprehensive review on the output voltage/power of wearable thermoelectric generators concerning their geometry and thermoelectric materials

Cited by 80 publications

References 168 publications

A Bi2Te3-Filled Nickel Foam Film with Exceptional Flexibility and Thermoelectric Performance

A Bi2Te3-Filled Nickel Foam Film with Exceptional Flexibility and Thermoelectric Performance

A Liquid Metal-Enhanced Wearable Thermoelectric Generator

Flexible n-Type Abundant Chalcopyrite/PEDOT:PSS/Graphene Hybrid Film for Thermoelectric Device Utilizing Low-Grade Heat

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