# Unique Triboelectric Nanogenerator Using Carbon Nanotube Composite Papers
## 3 Results  
### Performance Evaluation of TENG Using CNT Composite Paper  
After the CNT composite papers were prepared by following the methods described in Sections 2.1 and 2.2, they were configured as TENGs. Table 2 shows the typical properties of the fabricated CNT composite papers. In the table, a variation in the thickness of the resulting CNT composite paper can be seen. However, the thickness was not deliberately changed. Sample preparation is a manual process, which inevitably results in variations. Due to the use of paper, there were also many surface irregularities. The amount of pulp used in the sample preparation was set at a fixed value, as described in Section 2, so the ratio of CNTs to pulp was also set at a fixed value. Therefore, this variation was considered to be generally acceptable. If the process of CNT composite paper production is mechanized in the future, it is expected that the thickness variation will be resolved.  
Figure 5 shows the results regarding power generation with the TENGs placed in the apparatus, as shown in Figure 3. Here, the potential change in the load resistance was observed with an oscilloscope. From the output results, positive and negative peak voltages appeared alternately in a constant rhythm for all CNT composite papers. These represent distinctive waveforms in triboelectric power generation. In other words, it was confirmed that CNT composite papers can be used as TENGs. Figure 6 shows the RMS values calculated based on the oscilloscope measurements. Triboelectricity generation was observed for the SG101, (6,5)-chirality, and (7,6)-chirality CNTs with semiconducting properties and NC7000 CNTs with metallic properties. There was no significant difference in the magnitude of the output. These results suggest that, in triboelectricity generation using CNT composite papers, the CNTs may not serve to increase the output but rather assist in charge transfer within the composite paper. As described in the Introduction, unlike other typical plain materials, the CNT composite paper has a unique structure in which the CNT network is embedded in a network of paper fibers. According to Table 1, each CNT composite paper showed low resistivity. Generally, low-resistance materials are not preferred as TENG materials. However, it is considered that the low resistivity is not necessarily a disadvantage when using CNT composite papers because they have a mixture of surfaces that are advantageous for triboelectricity generation (pulp area) and surfaces that can easily collect the generated charge (CNT network area) if viewed locally.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline
**Sample No.** & **1** & **2** & **3** & **4** & **5** & **6** & **7** & **8** \\ \hline CNT & SG101 & (6,5) & (7,6) & - & SG101 & (6,5) & (7,6) & - \\ Pulp [mg] & 200 & 200 & 200 & 200 & 100 & 100 & 100 & 100 \\ \hline \end{tabular}
\end{table}
Table 1: Conditions for sample preparation.  
\begin{table}
\begin{tabular}{c c c c c} \hline
**Contained CNTs** & **SG101** & **(6,5)** & **(7,6)** & **NC7000** \\ \hline Sheet resistance [\(\Omega\)/sq.] & 2.88 & 16.54 & 75.12 & 42.20 \\ Thickness [mm] & 0.081 & 0.099 & 0.098 & 0.063 \\ \hline \end{tabular}
\end{table}
Table 2: Measured properties of fabricated CNT composite papers.  
Figure 5: Triboelectricity generation results for four types of CNT composite paper. (**a**) SG101, (**b**) (6,5)-chirality, (**c**) (7,6)-chirality, and (**d**) NC7000.  
Figure 6: RMS values of output derived from Figure 5.