Colloquia

Summary

Mentech's stress recognition platform aims to predict stress in individuals with limited verbal communication abilities, preventing misunderstood behaviour and ensuring adequate interventions. This platform includes wearable devices like the SentiSock, which measures electrodermal activity on the foot, and a strap with for heart rate monitoring.  Some clients face challenges with the SentiSock and require alternative options. Stress can be detected through decreased heart rate variation and increased respiratory rate. Therefore, this thesis aims to design an undershirt integrating ECG electrodes for heart rate monitoring and a strain gauge for respiratory rate monitoring.

The integration of screen-printed electrodes focusses on optimizing skin-electrode contact using stretchable fabrics and strategic electrode placement to minimize interference from various factors. After prototyping and testing various designs, the most effective configuration is found to be placing the electrodes for heart rate detection underneath the breast, with a fabric composition of 13% elastane and 87% nylon. This location requires lamination of the electrodes at the correct height for women with varying breast sizes to ensure functionality while walking. Future research includes conducting functionality tests with the target group over a 12-hour period to better understand how the electrodes function and how clients react to the shirt over an extended period.

For respiratory monitoring, the strain gauge is designed to detect volumetric changes in the thorax and abdomen through a sinusoid pattern. Testing revealed some issues with degradation and sensitivity, leading to an iterative design process to enhance stretchability and achieve a higher resistance change. Future research requires the manufacturing and testing of this design.

Regarding the electronics module integration, non-obtrusive placement at the Xiphoid Process is considered to prevent clients from removing it and making it manufacturable. Nevertheless, there is still the possibility of removal. Therefore, drop simulations evaluate the impact resistance when it is thrown onto the ground, which resulted in the optimization of the design by adding ribs, gussets, and material changes. Future research requires conducting user tests with the target group to get a better understanding of their behaviour toward the location and design of the electronics module.