Fabrication and Evaluation of Woven and Crocheted Strain Sensors for Soft Rehabilitation Robots

Recent advancements in technology have made possible the use of soft wearable mechatronic devices for musculoskeletal rehabilitation. Soft sensors are crucial components of these devices, as they are used for user data collection and device control. However, current fabrication methods are expensive, complex, and not available to those in low resource communities. To address this issue, this paper presents advances in low-cost textile sensors created using either crocheting or weaving. The performance of four different types of sensors was evaluated in terms of working range, linearity, hysteresis, sensitivity, and repeatability. The results showed that a fully crocheted sensor made with elastic and silver-plated conductive thread performed the best. This sensor demonstrated high repeatability, an excellent working range (49.76%), and relatively good hysteresis ($20.12 \pm 19$) and linearity ($R^{2}$ of $0.7741 \pm 0.03$). Overall, these results indicate that soft textile strain sensors created using simpler techniques, such as crocheting, have the potential to be used in applications requiring tracking of human motion, meaning that they could be used as integral components of soft wearable robots. This low-cost approach could make soft wearable rehabilitation technologies more accessible and affordable, paving the way for broader implementation and improved patient outcomes.