Development of highly sensitive and stable patterned PDMS flexible strain sensors for motion monitoring via laser direct writing

Flexible strain sensors have received widespread attention for their potential applications in wearables, human-computer interaction, and healthcare. However, achieving a good balance between sensitivity, stretchability, and stability remains challenging. Here, we report a cost-effective and scalable fabrication strategy that combines laser direct writing (LDW) with 3D printing (3DP) to prepare various patterned Polydimethylsiloxane (P-PDMS) flexible strain sensors. By varying the laser parameters and processing paths, different microstructured patterns can be obtained, which significantly influence the sensor's performance. By introducing patterned composite microstructures, the sensitivity of the strain sensor was increased by 339 % compared to the sensor without surface structures. Additionally, the strain sensors exhibit high stability and durability, a fast response time (140 ms), low hysteresis (0.009), and an ultra-low detection limit (0.0125 % strain). Besides, the sensors demonstrate excellent electrical performance and thermal stability. Based on their superior performance, we demonstrated their capability for real-time monitoring of human physiological signals. These findings successfully illustrate the potential of laser processing in fabricating complex microstructures, enabling the development of high-sensitivity flexible strain sensors for applications such as wearable health monitoring and human-computer interaction.