Abstract
The outstanding properties of graphene have initiated myriads of research and development; yet, its economic impact is hampered by the difficulties encountered in production and practical application. Recently discovered laser-induced graphene is generated by a simple printing process on flexible and lightweight polyimide films. Exploiting the electrical features and mechanical pliability of LIG on polyimide, we developed wearable resistive bending sensors that pave the way for many cost-effective measurement systems. The versatile sensors we describe can be utilized in a wide range of configurations, including measurement of force, deflection, and curvature. The deflection induced by different forces and speeds is effectively sensed through a resistance measurement, exploiting the piezoresistance of the printed graphene electrodes. The LIG sensors possess an outstanding range for strain measurements reaching>10% A double-sided electrode concept was developed by printing the same electrodes on both sides of the film and employing difference measurements. This provided a large bidirectional bending response combined with temperature compensation. Versatility in geometry and a simple fabrication process enable the detection of a wide range of flow speeds, forces, and deflections. The sensor response can be easily tuned by geometrical parameters of the bending sensors and the LIG electrodes. As a wearable device, LIG bending sensors were used for tracking body movements. For underwater operation, PDMS-coated LIG bending sensors were integrated with ultra-low power aquatic tags and utilized in underwater animal speed monitoring applications, and a recording of the surface current velocity on a coral reef in the Red Sea. Versatile and wearable graphene sensorsPrinted laser induced graphene (LIG) enables versatile multiple-parameter piezoresistive sensing in actual fields. An international team led by Prof Jurgen Kosel from King Abdullah University of Science and Technology, Saudi Arabia develops bending piezoresistive sensors based on laser induced graphene (LIG) on flexible polyimide substrate to accurately detect curvature, force, deflection and flow. When combined with double-sided device design to complete compensate the temperature effect and commercial ultra-low power aquatic tags, the LIG sensors can be used for various marine life measurements and monitoring, such as marine animals' speed monitoring under realistic and harsh conditions. These LIG sensors presented here fulfill several key requirements such as low cost, light weight, flexibility and minimal intrusiveness and are thus promising for future applications in wearable electronics.