A new strategy for balancing sensitivity and stretchability in strain sensor with well-controlled high-density cracks

With the increasing demands in new application such as wearable electronics, human health monitoring, and soft robotics, high-performance strain sensors with high sensitivity, and high stretchability, with the ability to measure both tensile and compressive strain, are highly desirable. However, based on the reported studies, it is difficult to get a strain sensor with both high sensitivity and high stretchability. Also, the response of the many strain sensor is nonlinear which makes their practical application difficult. Here, we introduce a strategy in which a carbon nanotube paper was embedded into an elastomeric substrate with laser-engraved technology to well control the crack density. Then the pre-cracks were changed into through-thickness cracks by a roll-to-roll process. This sensor can maintain high sensitivity with good stretchability (with a GA of over 4.2 × 10⁴ at 150% strain which is three times greater than that of no pre-cracked sensor). By changing the sensor's substrate to a thermoplastic polymer, and applying a stretching-stress-releasing process, we are then capable of designing a highly-sensitive compressive strain sensor.