Laser-Induced Graphene-Based Pressure Sensor With Corrugated Polyimide Diaphragm

Until now, various types of pressure sensors, including piezoresistive and capacitive types, have been developed using the technology of microelectromechanical systems (MEMSs). However, many of these sensors require complex fabrication processes, making it challenging to form 3-D shapes. In contrast, laser-induced graphene (LIG) shows promise for use in various physical sensors due to its high sensitivity as a piezoresistive material and its simple fabrication process. Polyimide (PI) substrates, commonly used for LIG formation, can be easily grooved and cut by ultraviolet (UV) lasers, allowing for the fabrication of 3-D shapes. In this study, we propose a two-gauge corrugated-type pressure sensor with LIG strain gauges on both the top and back sides of a PI substrate featuring a corrugated structure. The fabrication process involves using a UV laser to fabricate the corrugated structure and a CO2 laser to form the LIG strain gauges. This simple process produced a sensor with dimensions of 10 mm in length, 15 mm in width, and a total thickness of 6 mm. The corrugated sensor deformed 1.8 times more under pressure and demonstrated three times greater sensitivity than the membrane-type PI sensor. This approach is effective for low low-volume production of a large variety of sensors in laboratories because it enables simple design and fabrication using only two types of lasers.