Eating too many calories in a sitting, or frequently snacking, can lead to excessive weight gain and many health problems, including high blood pressure and an increased risk of cancer. However, behavioral habits such as overeating can be very difficult to break. Sometimes bad habits can be changed by creating a heightened awareness of the problem.
Raising awareness is just what a research team from Northwestern University is seeking to do with their wearable device called NeckSense. NeckSense is a sensor-laden necklace that passively tracks when a wearer is eating or drinking throughout the course of the day.
The device is centered around a Nordic nRF52832 SiP with an Arm Cortex-M4 CPU and Bluetooth Low Energy for wireless communication. Proximity, ambient light, and IMU sensors are also embedded within the necklace. The low-power devices chosen allow for 15.8 hours of run time with a small 350mAh battery pack.
The proximity and light sensors are angled upward, towards the jaw, to capture chewing movements. The IMU is used to detect when the wearer is leaning forward or backward — forward leaning is indicative of eating, whereas leaning backwards hints at drinking. A real-time clock module is used to track eating times, and also to determine if a set of gestures meets the researchers criteria for a chewing event.
Friedman’s Gradient Boosting Algorithm was used to classify time sequences of chewing gestures and thereby infer if the wearer is eating. In a study of 10 individuals wearing the device over a two day period, NeckSense was found to detect eating with an average F1-score of 73.7%.
The researchers hope to refine the current prototype into a smaller design in the future that will be more appealing to users. They also note that future work is needed on the algorithms — for example, if someone is lying down, or otherwise in an unexpected position, it confounds the device’s ability to detect eating events. Low light levels are also problematic, so those midnight snacks may go unnoticed.
These refinements should go a long way towards making NeckSense a more usable device, but the question that has still to be answered is whether or not anyone wants a necklace that tells them how much they eat. It is also worth mentioning that NeckSense has no idea what you are eating — hamburger or hummus — it is all recorded the same way, so the value of the data will be limited without adding more invasive (and less desirable) sensory components.