Flexible and highly sensitive sensors are key elements in advanced wearable or implantable sensing devices. With the ability to transduce external stimuli (e.g., pressure and temperature) into electronic signals, sensors have attracted a great deal of attention because of its wide potential applications.
In pressure sensors, sensitivity is a crucial parameter for accurate monitoring. There are mainly four types of pressure sensors based on piezoelectric, capacitive, field-effect sensing mechanisms, and piezoresistive.
Owing to its unique electrical and mechanical characteristics, graphene is promising as the building block for assembled architectures approaching application in piezoresistive sensors.
In this new work, the team demonstrates an ultrasensitive pressure sensor based on a fully air-bubbled ultralight graphene block, using a simple sparkling approach toward large-scale production. The specifically prepared sparkling graphene block (SGB) has excellent elasticity, which can rebound a steel ball with ultrafast recovery speed (∼1085 mm s-1) and features particular well-connected hierarchical bubble cavities with a low density of 3.7 mg cm-3.
As the researchers point out, The SGB shows a small-strain Young’s modulus of 1.1 kPa and a remarkable low maximum compressive stress of 2 kPa at 95% compressive strain. The pressure sensor based on the SGB demonstrates a superior pressure sensitivity of 229.8 kPa-1 to extremely low pressure (0-0.1 kPa), which is the highest among other graphene-based piezoresistive pressure sensors.
"As a result, the SGB pressure sensor can detect extremely tiny disturbance such as breeze beyond the touch with a dandelion, a feather, and a hair," the authors conclude their report. "With the sensitive performance in response to the bending and twisting process, the SGB exhibits great potential for multifunctional sensing applications."