Design of ultra-low power processer for human sensing

摘要

The declining birthrate, the aging society and lifestyle diseases such as heart disease and diabetes related to changes in the social environment have raised interest in safety, welfare and health care problems. In order to live healthily from these social problems, it is very important to observe our daily activity and physical condition continuously which we call “human sensing” with no assistance of others and to detect serious diseases at an early stage. It is also necessary that the system should be compact, long-term usable and sold at lower price for many people to make daily measurements without discomfort. We have been developing a small and low power MEMS (Micro Electromechanical Systems) devices and integrated circuits. And we aim to develop low power consumption devices, sensors and power generation devices from MEMS technologies for this system. In this study, we would discuss mainly the integrated circuit part which has an important role to control the whole system. Human sensing device aims to acquire five data that including ECG (Electrocardiogram), acceleration, atmospheric pressure, temperature, and humidity. However, ECG and acceleration can change quickly so that it requires higher sampling rate although other sensors are not required. The higher sampling rate increases power consumption because of a higher operation frequency. We have developed a special circuit that extracts valuable data such as the heart rate from the ECG, the maximum and minimum values of acceleration, and the number of steps from the acceleration with low power consumption. Moreover, we are designing analog front-end circuit and digital circuits such as MPU (Micro Processing Unit) and memory in one chip by using CMOS technology. These works enable long-term operation and miniaturization of the human monitoring system.