Direct ink writing of three-dimensional thermoelectric microarchitectures

Abstract

Micro-thermoelectric modules can be used to develop unique components such as energy harvesters, active coolers, and thermal sensors in various integrated systems. However, the manufacturing of these modules still relies on costly traditional micro-fabrication processes, producing only two-dimensional (2D) thermoelectric lms. This limitation severely constrains temperature gradient formation across thermoelectric lms, and hence, the su cient amount of power required to run integrated systems is not generated. Herein, we present the direct ink writing of micro-scale three-dimensional (3D) thermoelectric architectures for fabricating high-performance micro-thermoelectric generators. The characteristics of (Bi, Sb) 2 (Te, Se) 3 -based particles were precisely engineered such that the colloidal inks achieved outstanding viscoelasticity, thereby facilitating the creation of complex 3D architectures having high thermoelectric gure-of-merits of 1.1 (p-type) and 0.5 (n-type). Micro-thermoelectric generators made of 3D-written vertical laments exhibited large temperature gradients and a good resulting power density, opening an avenue for the cost-effective and rapid manufacturing of integrated micro-thermoelectric modules. Main TextMicro-thermoelectric (μ-TE) modules have been regarded as potential electronic components that can generate power from minimal heat ow or act as coolers for local heat management 1,2 . Depending on the dimensions of the TE legs, μ-TE modules can be easily integrated into various emerging systems such as Internet of things-based devices, wearable electronic devices, wireless sensor networks, and lab-on-achip devices [3][4][5] . Most of these systems are expected to be energy autonomous because they are usually embedded in enclosed environments or packaged within inaccessible structures [5][6][7] . In this context, μ-TE modules can provide a unique solution for ensuring sustainable electricity supply owing to their advantages of a simple device structure, high reliability and durability, and maintenance-free operation.Moreover, μ-TE device arrays can potentially be used in applications involving high-resolution infrared image sensors, gas sensors, and thermal imaging sensors 8 .Advancements in micro-electromechanical system (MEMS) technology have facilitated the design and fabrication of micro-scale integrated systems consisting of multiple functional units of electrical and mechanical components 9 . This micro-fabrication process based on traditional lithography, deposition, etching, and release also allows us to create patterned, planar two-dimensional (2D) TE legs and electrodes in a μ-TE module with a thickness of tens of micrometres 10,11 . However, the mass fabrication techniques used in MEMS technology have the potential problem of costly multi-step complicated processes, which rely on expensive lithography equipment. More importantly, these 2D design processes are not suitable for the fabrication of structural three-dimensional (3D) TE legs with high aspect ratios in a μ-TE module; this 3...

Direct ink writing of high-performance Bi2Te3-based thermoelectric materials using quasi-inorganic inks and interface engineering

“…11 Wastage and complexity of procedures push the cost to a high level. 12,13 Advances in module customization are thus a paramount need to endow TEGs with design-exibility and cost-competitiveness.…”

“…Direct ink writing (DIW), a type of extrusion 3D printing technology, has recently emerged as a convenient and low-cost method of constructing custom-built shapes. [14][15][16] To date, many TE materials and devices including conducting polymers, 17,18 Bi 2 Te 3 -based, 13,19 PbTe-based, 20 and Cu 2 Se-based 21 compounds can be printed. Nevertheless, the ZT values of 3D-printed materials are lower than those of bulk counterparts.…”

“…[24][25][26] Furthermore, the pores created from the pressureless sintering process also hinder the transportation of electrons. 13,20,21,27 Therefore, organic residuals and porosities are the longstanding challenges in ZT enhancement, which so far has not been achieved in DIWed TE materials.…”

Generalised optical printing of photocurable metal chalcogenides

“…This is in stark contrast to the direct ink writing (DIW) techniques, which is an extrusion-based 3D printing method to create meso- and micro-scales architectures. By developing the viscoelastic inks containing inorganic particles, the DIW has been extensively utilized for fabricating various types of functional inorganic materials 18 – 20 . For example, the DLP-printed thermoelectric BiSbTe materials was reported to exhibit the ZT value of 0.12, which is one order of magnitude lower than that of inorganic bulk reference materials or that of even DIW-printed BiSbTe because the printed objects contain organic residues 21 .…”

Simple low-cost 3D metal printing via plastic skeleton burning

“…Additive manufacturing enables exploring complex volumetric structures across variety of fundamental and applied disciplines 1 . The range of new capabilities allows reconsidering conventional approaches in mechanics 2 – 4 , thermal management 5 , medicine 6 , robotics 7 , electronics 8 , 9 , and many others applied areas, e.g. 10 , 11 where novel architectures and material platforms can grant ever foreseen capabilities.…”