Carbon Nanotube/Biomolecule Composite Yarn for Wearable Thermoelectric Applications

In this work, yarn made of a hybrid material of carbon nanotubes (CNTs) and artificial biomolecules is created for the wearable thermoelectric (TE) module. Among the limited methods due to the sensitivity of proteins, the co-use of the ionic liquid and polymeric surfactant with the dialysis method is found to be effective for the dispersion of the CNT/biomolecule composite with a low CNT loss rate and high coverage by biomolecules on the CNT. This new method improved the TE performance by decreasing the bundle diameter of the CNT/C-Dps nanocomposite and better tensile strength. The incorporation of a biomolecule, in particular, significantly reduced the thermal conductivity of CNT yarns, demonstrating that the hybrid composite is advantageous for wearable device applications. This method also outperformed the conventional dispersion against the pristine CNT yarn (without protein), demonstrating the application’s generality. Finally, a low-density testing of the TE module using the CNT/biomolecule composite is demonstrated, exhibiting the output power of 4.37 μW m–2 with a thermoelectric voltage of 4.5 mV at a temperature difference of 20 K. The output power density and voltage can be easily increased 500-fold by increasing the density of the yarn and the number of series connections. This study proposes a practical method for producing an environment-friendly CNT/biomolecule hybrid yarn, which has the potential to be useful in future wearable TE applications.