A Heart Rate Finger Ring and Its Smartphone APP Through Customized NFC
Yang Liu · Rose-Hulman Scholar (Rose–Hulman Institute of Technology) · 2015
Population aging has become one of the most critical problems in contemporary society. Families and organizations are striving to provide better healthcare to the elderly and handicapped for their better living conditions. Due to these situations, the demand for remote health monitoring continues to grow rapidly. With the development of new technologies, such as smaller sensors and microcontrollers, the increasing widespread use of smartphones, and new wireless communication methods, a wireless body area network system can be constructed to provide more sophisticated solutions to satisfy this demand. The objective of this thesis is to demonstrate that such a system is feasible. A ring-shaped hardware device is implemented to measure the user’s heart rate and transfers the data to an Android phone through a customized Near Field Communication (NFC) tag. The tag is composed of a transponder to write data and a customized antenna to transfer data based on the resonance effect. An application is also developed to operate the NFC module to communicate with the tag. Data is then received, stored, and utilized on the phone. The ring and Android phone serve as Body Sensor Unit (BSU) and Body Central Unit (BCU) respectively in the Wireless Body Area Network (WBAN) system. Then NFC technology links them together wirelessly. In order to implement the NFC Ring, a sensor is placed within the ring to convert the heart rate into an electric signal. This signal is filtered and amplified and sent to a microcontroller. Next, the microcontroller generates a count for computing the time interval between two pulses. Then the count value is written to the NFC tag through an NFC transponder. The antenna is specially designed to meet two core constraints: the size should be as small as possible to fit the ring, while still maintaining the ability to produce a large enough magnetic field. When an Android phone approaches the ring, the application on the phone will execute and read data in the tag by controlling the NFC reader. After being received, the data is stored in a SQLite database on the phone for further processing, such as rendering a history chart to show the trend. A prototype of this system has been developed to demonstrate the idea. This prototype can accurately read the heart rate per minute. Compared with a Radio-Frequency Identification ring, the NFC Ring has reduced system complexity and improved mobility. There are many possible improvements on both hardware and software. For instance, more research on NFC antenna design to enhance the stability of data transmission should be considered. The algorithm of heart rate measurement may be refined to generate more accurate data. More explanation of heart rate data and its trend await further exploration as well.