Monitoring Daily Energy Expenditure using a 3-Axis Accelerometer with a Low-Power Microprocessor

Recent mobile phones are capable of monitoring a userʹs contextual information because they are equipped with computational, communication, and sensing abilities, and because people carry them continuously. This paper describes software that accurately monitors energy expenditure using a mobile phone handset equipped with a 3-axis accelerometer. This approach differs from other attempts because it detects non-exercise activity thermogenesis (NEAT) as well as active exercise (walking and running) regardless of the sensor position on the body. All the signal-processing tasks are implemented by the low-power 8-bit PIC microcontroller. Total power consumption is almost as much as that of the stand-by power consumption of mobile phones. Evaluation results indicate that this technology can monitor energy expenditure as accurately as a medical calorie meter.