Menstrupal : a smart sensor to monitor menstrual rhythm

Abstract

Ubiquitous health monitoring systems are gaining a lot of interest due to their potential to provide continuous, real-time information via non-invasive measurements of physiological parameters. Menstruation is a periodic biological process that is essential for women’s health. In this report, we described a textile-based blood volume sensor that can be integrated into the sanitary napkin to quantify menstrual blood loss during menstruation. Through benchtop characterization tests with 5 mL of saline fluid, we determined the effect of spacing, orientation, weight, and location of fluid drop on the sensor. The sensor has been evaluated by intravenous blood samples collected from 18 participants and menstrual blood samples collected from 10 participants for four months. The collected intravenous blood samples and menstrual blood samples were used to create two regression models that can predict the blood volume and menstrual blood volume from the voltage input with Mean Absolute Percentage Error (MAPE) of 11-15% and 15-30%, respectively. We also presented a modified design of the sensor and the result of a 10 participants user study to evaluate the effect of activities performed by the users. We showed that the sensor performs uniformly for all activities across the users. Through a user experience study, we found that the wearable sensing system is comfortable and safe to use. Further, we explored the design of a battery-less wearable sanitary napkin system to test the feasibility of data collection using an NFC-enabled smartphone.