Physical Sensors Based on Laser-Induced Graphene: A Review

Abstract

Physical sensors form the fundamental building blocks of a multitude of advanced applications that detect and monitor the surroundings and communicate the acquired physical data. The everlasting need for more compliant, low-cost, and energy-efficient sensor solutions has led to considerable interest in enhancing their features and operation limits even further. While graphene has emerged as a promising candidate material, due to its outstanding electrical and mechanical properties, it is still not available in large volumes for practical applications. Meanwhile, Laser-Induced Graphene has opened new perspectives for a versatile, durable, printed physical sensing platform capable of detecting various physical parameters across a range of conditions and subjects. In this review, LIG physical sensors were categorized into four broad types based on their transduction mechanism: mechanical, thermal, magnetic, and electromagnetic. We summaries various design strategies established for preparing reliable physical sensors without the involvement of chemical treatments, synthesis, and multi-step fabrication processes. The review considers the effects of laser choice, lasing environment, and parameters on graphene properties. We also discuss a broad spectrum of applications of LIG physical sensors in fields ranging from healthcare, tactile sensing, environmental monitoring, energy harvesting, and soft robotics to desalination and THz modulation.

Enhanced Graphene Sensors via Multi-Lasing Fabrication

“…It was found that the resistance of LIG electrodes reduces by 4% over a temperature range of 20-60 °C. [5,50,51] Full temperature compensation was recently obtained by scribing the LIG patterns on both faces of the substrate and utilizing a difference measurement. [2] In this study, the double-sided sensor configuration also provided an increased sensor sensitivity of 1108 Ω/mN and 712 Ω/mm with zero output voltage under no-load condition (Fig.…”

“…HE potential and versatility of bending sensors made of porous graphene were recently demonstrated for an extensive range of configurations, including measurements of force, curvature, and speed [1][2][3][4][5]. The deflection caused by a wide range of forces and speeds was effectively sensed through a resistance measurement, exploiting the piezoresistance of the scribed graphene films [2,3].…”

“…The graphene electrodes were realized using flexible and lightweight polyimide (PI) films and a simple laser scribing process, creating what is known as Laser-Induced Graphene (LIG) [6]. This facile fabrication process is a combination of large-area graphene growth and patterning in one step, without using any high-cost cleanroom facilities, wet chemical processes, and consecutive treatments [5]. Besides these advantages, LIG is also corrosion-resistant [7][8][9] and can operate at high temperatures of up to 580° [5,10].…”

“…This facile fabrication process is a combination of large-area graphene growth and patterning in one step, without using any high-cost cleanroom facilities, wet chemical processes, and consecutive treatments [5]. Besides these advantages, LIG is also corrosion-resistant [7][8][9] and can operate at high temperatures of up to 580° [5,10]. Thus, LIG has shown its suitability to be utilized in several physical domains.…”

“…Although the sensitivity and dynamic range of the sensors could be tuned via the sensor geometry, the overall resistance variation was limited to a maximum of 10% and a gauge factor of ~ 11. [5] A larger change in the value of resistance for a small change in strain would allow more accurate and subtle detection of deflection, force, and curvature, which is crucial in many automotive, industrial, and medical applications. The electromechanical performance of LIG has previously been enhanced by increasing the laser power within a certain range [6,19,20] or by transferring the LIG pattern to an elastomeric substrate, such as polydimethylsiloxane [11,12,21] , silicon rubber [22,23] , or polystyrene [13,24] .…”