Inkjet Printing And Intense Pulsed Light Sintering Of Multiwall Carbon Nanotubes For Sensor Applications

Fully inkjet-printed multiwall carbon nanotube (MWCNT) layers and their feasibility towards the implementation as a low cost and flexible sensing element is reported. The focus is set on the resistive behavior of the carbon nanotubes (CNTs) and the adjustability towards a defined target range. To realize the sensors on a low cost and high flexible polyethylene terephthalate (PET) foil, the intense pulsed light (IPL) sintering is introduced to achieve the required performance for both the CNT dispersion as well as the silver electrodes. The very novel topic of the simultaneous photonic sintering of a two-material layer stack and the involved challenges are demonstrated. The MWCNT dispersion was successfully printed with the inkjet printing technology and functionalized by thermal and IPL sintering methods, achieving a resistance of 100 k Omega in the target area (1 k Omega to 1 M Omega) for the sensor. The dependence of the resistance on parameters like number of CNT overprints, the pattern layout as well as the post-treatment methodology is analyzed in detail. These results can be further employed for the development of CNT-based sensor elements and the change in their resistance caused by environmental conditions. In addition, such single sensors raise the opportunity of a combination to a sensor matrix to demonstrate the integration in applications such as a shoe sole (proof of concept) but primarily for medical applications e.g., in mattresses in hospitals for constant recording of bedfast or comatose patients. (C) 2018 Society for Imaging Science and Technology.