Laser-Induced Graphene Cantilever Airflow Sensor Fabricated via Laser Cutting and Folding a Copper–Polyimide Film

Abstract

Various animals in nature, particularly insects, are equipped with sensory hair capable of detecting minute fluid forces. Inspired by these biological structures, numerous airflow sensors have been developed using Si-based microelectromechanical systems. However, the complexity of the fabrication process and difficulty in integrating shape-controlled sensing elements remain significant challenges. Laser-induced graphene (LIG) has attracted increasing attention as a promising material for various physical sensors, owing to its high piezoresistive sensitivity and simple fabrication process. Polyimide (PI), which is widely used as a substrate for LIG formation, exhibits thermoplastic properties that enable the straightforward creation of 3D structures. This study proposes a single-axis airflow sensor featuring a vertically standing LIG cantilever. The fabrication process involved only a fiber laser for cutting the PI film, forming the LIG-sensing elements, and folding the cantilever structure. The fabricated sensor measured 25 mm × 25 mm at the base and 10.5 mm high. The fabricated sensor integrated surface-mounted circuits within its base. Wind tunnel experiments demonstrate that the sensor exhibits a quadratic response to wind speeds between −10 and 10 m s⁻¹. This approach offers promising prospects for the development of 3D LIG sensing elements for airflow sensors.