With the escalating use of portable electronics, wearable generators are highly desired as a potential power supply to harvest electricity from human body, such as body motions, body heat, et al. Assembling generators into fabric is the most effective way to achieve wearability. However, the 2D architecture of fabric limits their application in energy conversion, particularly in thermoelectrics, because a good matching between thermoelectric (TE) modules and effective thermal gradient direction is required. Although a supporting substrate can enables a 3D architectures, the substrate always sacrifice the comfort and output performance.
How to make the flexible fibers self-support in 3D space without substrate? And how to fulfill the following requirements simultaneously to achieve practical application of wearable TE generators: i) TE modules possess stable and high performance, particularly its n-type segment; ii) high flexibility to enable sufficient thermal contact with body tissues of arbitrary geometry; iii) many micro-fabricated p/n junctions per area in compact design for sufficient voltage; iv) scalable architecture design to unobtrusively collect heat over a wide area to provide higher power; v) stretchable and conformal architecture of overall device design to allow body movement without performance degradation; vi) architecture enables the intended thermal insulation of the textile while at the same time facilitates heat transfer through the thermoelectric generator.
In this work, Wan Jiang and Lianjun Wang from Donghua University and Gerald Jeﬀrey Snyder from Northwestern University teamed up to report a 3D thermoelectric fabric woven out of thermoelectric fibers producing an unobtrusive working thermoelectric module. π-type carbon nanotube fiber-based module with stable performance and optimized thermal design is developed using electrospray technology and coverspun technique. Utilizing elasticity originating from these interlocked thermoelectric modules, stretchable 3D thermoelectric generators without substrate can be made, which distinguishes it from reported textile based TE devices, as shown in the following figure.
Finally, integrating the high TE performance π-type modules into the logical architecture design contributes to a superior power density of 70mWm-2 at 44K and excellent stretchability of ~80% strain. And the compatibility between body movement and sustained power supply is further displayed. It is the first time TE modules made by weaving into truly stretchable textiles compatible with body movements, instead of embedding them into clothes and avoids sacrificing flexibility and output power.
The compatibility with body movement and the superior power density certify the applicability of our TE generator design in electricity supply by body heat.
For more details, please read the full article here: https://www.nature.com/articles/s41467-020-14399-6