Carbon-nanotube-based flexible devices using a mechanical transfer method

We describe a new method for the manufacture of single-walled carbon nanotube (SWCNT)-based electrical devices on flexible substrates. The method involves the deposition of a SWCNT films onto polydimethylsiloxane (PDMS) substrates from rigid substrates using the adhesive property of PDMS. This method is similar to the conventional dry transfer method, which is based on surface-energy modification, except that our method involves mechanical transfer using the adhesive property of PDMS under peculiar conditions. The gas-sensing characteristics of the resulting transferred SWCNT films are presented, showing, for example, that typical flexible sensors exhibit a sensitivity of 17.4% for 4-ppm NO ₂ in a vacuum at room temperature. The performances of the devices are slightly reduced when they are bent to a curved profile with a bending radius of 2 cm (15.9%). The field-emission properties are also investigated. From these emitters, the SWCNTs can be turned on with a field as low as 0.9 V/μm, and an emission current density of 0.75 mA/cm ² at 1.2 V/μm can be attained. Thus, a method for the fabrication of flexible devices is established, which should find practical applications in electronic devices.