The Role of Fracture Patterns on Crack-Based Strain Sensors

Crack-based strain sensors (CBS), which are inspired by a spider's slit organ, can provide highly sensitive measurement with great flexibility. Fracture pattern design holds the key to meeting different sensing needs. In this paper, a computational model is developed to understand the role of fracture patterns on sensitivity and sensing range of CBS that consist of a platinum (Pt) conductive layer and a polydimethylsiloxane (PDMS) substrate layer. Through the coupled mechanical-electrical finite element analysis, we found that a single Mode-I through crack can yield better sensing performance than a non-through crack in other orientations or a few discrete non-through cracks in the same orientation. Creating multiple Mode-I through cracks has negligible effect on sensitivity. However, increasing the number of cracks can lead to higher sensing range. When the same number of cracks are employed, even crack spacing can yield the highest sensing range. Sensitivity can be effectively improved by increasing the crack depth. Conclusions from the computational analysis can provide useful feedback for design and manufacturing of CBS in different applications.