**Author details**

involved chips and it is compatible with their dimensional and mechanical endur-

*New assembly route of the heat exchanger Si adapter onto the encapsulated μTEGs chip.*

*Heat Transfer - Design, Experimentation and Applications*

With this chapter, the authors have tried to show the challenges to sort out when fabricating microgenerators (μTEGs) with planar silicon technologies. Such technologies offer a cost effective way of mass-production of miniaturized devices. However, the very nature of such technologies, the high thermal conductivity of bulk silicon and the typical thickness of the layers involved advises using silicon micromachining to enable areas of lateral thermal contrast. Such transversal architectures helps to translate naturally occurring vertical thermal gradients into inter-

nal lateral ones. In this way, a temperature difference will develop across a

horizontally and self-standing laid thermoelectric material whose length is a design parameter. A material properties trade-off ensues: the longer the material, the higher its thermal resistance, increasing the attainable ΔT and the obtained Seebeck voltage, but the larger will be its electrical resistance, reducing the power obtainable from that voltage. In addition, it has been shown that the overall attainable ΔT is heavily influenced by the very poor heat exchange capabilities with the environment of small bare surfaces. Simulations and experiments show that the presence of a heat exchanger largely increase the effective ΔT, but brings into play interesting heterogeneous integration challenges still to be fully solved in terms of an effective

ance constraints.

**Figure 21.**

**368**

**5. Conclusions**

Marc Salleras<sup>1</sup> , Inci Donmez-Noyan<sup>1</sup> , Marc Dolcet<sup>1</sup> , Joaquin Santander<sup>1</sup> , Denise Estrada-Wiese<sup>1</sup> , Jose-Manuel Sojo2 , Gerard Gadea<sup>2</sup> , Alex Morata<sup>2</sup> , Albert Tarancon2,3 and Luis Fonseca<sup>1</sup> \*

1 Instituto de Microelectrónica de Barcelona, IMB-CNM (CSIC), Bellaterra, Spain

2 Institut de Recerca de l'Energia de Catalunya, IREC, Barcelona, Spain

3 Institució Catalana de Recerca i Estudis Avançats, ICREA, Barcelona, Spain

\*Address all correspondence to: luis.fonseca@imb-cnm.csic.es

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
