Wearable Vital Signs Monitoring System

Blood pressure, pulse, body temperature and respiration are the supports to maintain the normal activities of the body and the most important parameters of vital signs. It is very important for patients and medical staff to monitor the four vital signs parameters accurately and conveniently. At present, multi-parameter physiological monitor is powerful, but still has a strong professional, ordinary people difficult to operate; large volume, inconvenient carrying; the price is expensive, the general family is difficult to bear and so on. So, develop a miniaturization, simple operation, convenient in carrying monitoring equipment, become the development trend of the present monitoring equipment. The State Council issued the "China made 2025" has clearly defined the development of wearable medical devices will be the focus of the development of the field. Based on the above background, this paper designed a wearable vital signs monitoring system. The main contents of this paper are as follows:(1)On the measuring principle of vital signs, oscillography is used to measure blood pressure and pulse, integrated temperature sensor is used to measure body temperature, photoplethysmography is used to measure respiratory frequency. In the hardware system, using medical pressure sensor MPS-2107 of Taiwan Quanlei company to acquire blood pressure and pulse sensor, and using digital temperature sensor DS18B20 produced by Maxim Semiconductor to acquire temperature signals; Using transmission photoelectric sensor HKG-07 produced by Hefei Huake Electronic Research Institute to acquire respiration signal.(2)This system uses the high performance AVR controller- ATmega32 as the core control chip, complete the automatic control and adjustment of the measurement process, then the blood pressure, pulse, body temperature and respiratory parameters are displayed by LCD1602, which is convenient for patients to observe directly. At the same time, the monitoring system uses the wireless data transmission technology of Zig Bee to combine the information system of patients on the host computer and the wearable medical device terminal. It realized the wearable device’s wireless, network. Through the use of SQL Server database, a reasonable design of the patient’s information data interface, to achieve the patient’s information to add, view, modify, delete, and realize effective tracking of patient’s health condition.(3)This paper discusses the method of improving the respiratory frequency in the respiratory signal acquisition module. Aiming at the problem that exists in the traditional fast fourier transform in the calculation of the spectrum of pulse wave signal, a interpolating windowed FFT algorithm based on S-G filtering is proposed. The algorithm can effectively filter out the noise mixed in the weak signal, and can effectively reduce the spectral error due to the leakage of the spectrum and the fence effect, and greatly improve the calculation accuracy of the respiratory frequency.The experiment proves that the system has the advantages of small size, low cost, high stability and high accuracy. It can be widely used in home care, so that patients can understand their own health status. It can also be applied to the medical care system in the community, which can greatly reduce the operation cost of community hospitals, and reduce the workload of medical workers. Finally, this paper summarizes the research and design of the system, and puts forward the improvement measures and the next step of the work. Hoping to provide some reference for further research of future wearable monitoring equipment.