Implementation of a Threads-based Smart Insole Prototype for Gait Analysis

The aim of this work is to create a first intelligent insole prototype based on smart conductive threads technology, i.e. a threads resistance 2D map. The estimated future application foresees the use of the final device in the daily monitoring of the gait, in particular in elderly population, so as to reduce the risk of fall, therefore of accidents, which afflicts this segment of population. The experimental phase of the study focuses on different aspects. First, a fabrication platform based on the automated dip-coating approach is created, to improve the quality of the produced threads and to increase the reproducibility of these sensors. In a preliminary phase, a 2D threads architecture is created. A resistance map is made, generating an innovative concept of Wearable Flexible Touch Interface (FlexTi), able to recognize the point of the threads map subjected to the pressure stress. Subsequently, the behavior of the threads embedded in a soft scaffold is analyzed. Finally, the study faces the creation of the aforementioned prototype. The previous experimental steps are combined each other and a EcoFlex soft scaffold is used as a basis to embed a 2D network of twenty-four threads, replicating the FlexTi behavior at a higher level of complexity. Therefore, a PCB-based electrical circuit is created and it is equipped with a Bluetooth communication to a computer for data transmission. At the same time, a graphical user interface is created on Matlab for the device management and data collection. In the results section, all the thermometric characterization of the threads fabrication platform is discussed and the best configuration for dip-coating performance is chosen based on the acquired data. Subsequently, the results obtained in the preliminary phase are analyzed. The rightness of the data acquisition algorithm is highlighted starting from the 2D resistance map inside the FlexTi. Therefore, the results of the pressure tests performed on an initial prototype and finally on the final version of the insole produced by the study are analyzed through the corresponding colormaps. The obtained results are extremely satisfactory; the designed prototype ensures a high level of precision and sensitivity. In the future, the threads behavior should be made more stable on time, possibly improving the algorithm already proposed in this study. In addition, a farther step will be the analysis on the results of the tests carried out on several people inserting the sole directly into the shoes. Finally, an algorithm must be designed to recognize any anomalies shown by the step analysis to reach the goal this study started for.