Extremely Flexible and Stretchable Carbon Nanotube Composites for Conformal Electronic Devices

摘要

Electronic devices are increasingly being used in products that are not expected to be rigid and flat [1,2]. Many strategies have been implemented to create electronics that can work under stress and strain that would fracture ordinary silicon architecture [3,4]. Effective strategies, including zigzag and pre-stretched substrates, can only be effective in one dimension. For true flexibility, the conductive material itself must be designed to function under strain. Using composite materials allows conductive materials to gain some flexibility from the matrix without breaking the connections [5,6,7]. Brewer Science, Inc., has previously developed carbon nanotube–based inks for screen printing, stencil printing, Aerosol Jet printing, ink-jet printing, drawbar coating, and spray coating [8]. These materials exhibit high flexibility but very limited ability to stretch enough to meet requirements of many applications in wearable electronics. Brewer Science’s inks have been used to make explosives sensors, temperature sensors, humidity sensors, inductor coils, electrodes, and antenna structures. We report on an innovative class of printable carbon nanotube composites that maintain connectivity through strain as large as 400%. Through the use of an additive to our carbon nanotube ink, the conductivity of our materials is 47% of the original material conductivity at 100% strain. These materials can be screen printed and cured with standard screen-printing equipment for use in strain sensors with a very large operating range. Integration of such flexible and stretchable conductors and connectors will be a key enabler for wearable electronics.