a, b Finite element analysis (FEA) results showing the temperature distribution on the cross-section of the TEGs without (a) and with s-HCs (b) for a given temperature difference of 10 K. c, d FEA results showing the open-circuit voltage (VOC) of the 36-np-pair TEGs without (c) and with s-HCs (d) for a given temperature difference of 10 K. e, f Experimentally measured TE performances of 36-np-pair TEGs without (e) and with s-HCs (f) showing current and power as a function of voltage. g Schematic illustration of the experimental setup for measuring the response of the TEGs without and with s-HCs. h Time-resolved VOC of the two TEGs when the aluminum cup with hot water is abruptly placed in contact with the two TEGs. The dashed lines represent the corresponding FEA results. i Photograph showing the 220-np-pair-compliant TEG. j Experimentally measured TE performance of the 220-np-pair-compliant TEG including current and power as a function of voltage. k Performance comparison of wearable TEGs.