Wearable, near temperature insensitive laser-induced graphene nanocomposite strain sensors

Abstract

Soft and flexible sensors offer a potential paradigm shift in wearable bioelectronics to enhance human–machine interfacing for diagnosis, healthcare monitoring, and prosthetic applications. Soft nanocomposite strain sensors have emerged as a promising solution for the real-time monitoring of biomedical signals due to their conformability, stretchability, and resilience to different strain levels. Nonetheless, these sensors are susceptible to external factors like temperature variations, impeding their functionality in real-world applications. This paper introduces a strategy to tackle the considerable temperature sensitivity of nanocomposite strain sensors by fine-tuning the electrothermal properties of laser-induced graphene nanocomposites. The controlled manipulation of laser parameters governs the carbonization process, and the formation of 3D interconnected conductive networks, leading to nanocomposite strain sensors with temperature sensitivities as low as 0.25% °C⁻¹. These sensors enable real-time strain sensing with minimal interference from thermally induced noise in environments prone to significant temperature fluctuations, such as haptic feedback in prosthetics when grasping hot and cold drinks. Additionally, integrating this approach into the design of electrothermal soft actuators results in a self-sensing soft actuator with near-zero temperature sensitivity up to 100 °C, further demonstrating the versatility of these nanocomposite sensors.