The role of environmental factors in the deterioration of electrical properties in conductive nano-composites
Emma E. Bowden, Jacob D. Carter, Anton E. Bowden, David T. Fullwood Wearable nanocomposite stretch sensors are an exciting new development in biomechanical motion-tracking technology, with applications in low back pain, knee rehabilitation, fetal movement tracking and other fields. When pulled under a strain (for example when applied to the skin of the lower back and stretched by a patient completing physical therapy exercises), the sensors exhibit a measurable electrical response, which can be used to analyze human motion cheaply and accurately. However, current sensor technologies have exhibited rapid deterioration in the form of increased electrical resistance if left stored in normal room conditions.
The purpose of the present work was to evaluate the influence of several proposed environmental factors that could impact the deterioration of electrical properties of these sensors, including temperature, humidity, oxygen exposure, and light exposure. The electromechanical performance of sensors stored under each condition were compared against control sensors over a period of weeks. Our results showed that the presence of oxygen and humidity in the environment where the sensors are stored is the primary cause of the deteriorating electrical properties of the sensors. Sensors that are kept in de-oxygenated or desiccated environments do not deteriorate over time. This understanding allows for long-term storage of the sensors, and assists in gaining a greater understanding of the internal processes at work within the nanoparticle-polymer matrix, particularly as they relate to the interface between conductive particles and the polymer.