Development of Carbon-Nanotube Composite Thread and its Application to "Thread Transistor"

We propose development of a novel functional thread that contains carbon nanotubes (CNTs), i.e., a CNT-composite thread (CNTCT), and of a "thread transistor." The CNT is expected to be a next-generation material because it has a lot of useful characters, e.g., it can have both metallic and semiconducting characteristics. Thread is flexible and an everyday material. In our study, we succeeded in developing the CNTCT easily by dipping thread in CNT dispersion like dyeing. Here, we also developed and demonstrated a novel type of field-effect transistor (FET), i.e., the thread transistor. To do this, we prepared a metallic (M) and a semiconducting (S) CNTCT. The S-CNTCT was coated with a non-conductive paint as an insulating layer for simplicity. To construct the thread transistor, we tensed the S-CNTCT that plays the role of a channel for the FET and tied the M-CNTCT around the S-CNTCT as a gate electrode. The source and drain electrodes can also be materialized by tying the M-CNTCTs. As a result of measurement, a drain-to-source current could be measured on the order of micro-amperes. Moreover, the current could be controlled by the gate voltage.