Fully Handwritten Flexible Electrothermal Devices Using a Whiteboard Marker Pen with Carbon Nanoparticle Ink

There is a high demand for the design of high-performance electrothermal devices, including electrothermal films and actuators, with easy fabrication and low cost. Herein, flexible electrothermal films made of polyimide and carbon nanomaterials and bimorph actuators consisting of polythene and carbon nanomaterials are fabricated by a handwriting technique with a whiteboard marker pen filled with carbon aqueous conductive ink, which is simple and scalable. The electrical performance was examined through lightning diodes by drawing traces on various substrates to form a circuit. In addition, the performance of prepared handwritten devices was compared to that of screen-printed devices, and it was discovered that their performance was similar. The prepared electrothermal films can reach 122 °C with 10 V, and the bimorph actuator exhibits electrical actuation with reversible deformation of 221° under 5 V voltage within 20 s. Furthermore, a cross pattern composed of four pieces of the actuator was fabricated to demonstrate electrically driven actuation. These works provide a simple and fast method to fabricate electrothermal devices for intelligent fields and practical applications.