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SCIENTIA SINICA Informationis, Volume 48, Issue 6: 734-742(2018) https://doi.org/10.1360/N112018-00056

A transient thermal analysis of microscale inorganic light-emitting diodes

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  • ReceivedMar 22, 2018
  • AcceptedMay 9, 2018
  • PublishedJun 11, 2018

Abstract

Microscale inorganic light-emitting diodes ($\mu~$-ILEDs) that are integrated in flexible substrates are able to be deformed like a rubber band. Such flexible $\mu~$-ILEDs can be integrated with human tissue directly as a novel optical detector applied to human health monitoring and clinical diagnosis. However, large amounts of heat will be emitted when such devices are operating, and the heat-transfer characteristics of the device are critical for its applications. In this paper, an axial symmetry analytical model, validated by 3D finite-element analysis, is developed to describe the transient heat transfer process based on the separation variable method. Both the time and space variations of the temperature increase are obtained theoretically. According to the analytical model, the influence of the in-plane dimension ratio $R_{0}$/$R~$ on the steady-state temperature increase of the $\mu~$-ILED is discussed. These results are able to predict the heating process of flexible $\mu~$-ILEDs and also pave the basis for thermal management and relevant thermal design of flexible $\mu~$-ILEDs.


Funded by

国家重点基础研究发展计划(2015CB351900)

国家自然科学基金(11502009)

国家自然科学基金(11772030)

机械结构强度与振动国家重点实验室开放基金(SV2018-KF-13)


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  • Figure 1

    (Color online) A schematic of (a) the $\mu~$-ILED structure; (b) the axisymmetric analytical model

  • Figure 2

    The time variation of the temperature increase of $\mu~$-ILED (FEA: finite element analysis)

  • Figure 3

    (Color online) The distribution of the steady-state temperature increase at theencapsulation/substrate interface. (a) Analytic; (b) FEA

  • Figure 4

    The influence of the in-plane dimension ratio $R_{0}$/$R~$ on thesteady-state temperature increase of $\mu~$-ILED

  • Table 1   Geometric and material properties of each layer in finite elementanalysis
    Su8 $\mu$-ILED Hydrogel
    Thickness ($\mu~$m) 110 5 300
    Radius (mm) 5 0.5 5
    Density (kg/m$^{3})$ 1190 2329 1112
    Conductivity (W/m/K) 0.2 160 0.6
    Specific heat (J/kg/K) 1200 700 2375

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