BANDAGE SIZE NON ECG HEART RATE MONITOR USING ZIGBEE WIRELESS LINK Guided by,Presented by, Ms. Geo. P.G Jeevan.K.Noble Asst.Prof., ECE Dept.S7, ECE-A.

Introduction… Heart rate is an indication for the health of a human being. Traditionally, ECG signal is used to measure and monitor heart rate. This heart rate monitor design uses a simple technique to pick up the sound of the heart beat and send the beat signal wirelessly to a computer. The signal is processed, sampled and sent wirelessly using ZigBee protocol.

E.C.G. Fig: 1

System Design…  Heart rate sensing unit.  Wireless communication link.  A networkable computer and a database.

Overview of the system… Fig: 2

The sensing unit… Fig: 3

Block diagram… (sensing unit) Fig 4: Block Diagram of custom built heart beat sensor

Schematic Diagram… Fig: 5 – Schematic diagram of sensing circuit.

Wireless Link… The wireless link used is the 2.4GHz ZigBee based WPAN (the JN5139-EK010 made by Jennic). This is a low cost off-the-shelf microcontroller and wireless communications in a single unit. This is a light weight,small size module with a built-in ceramic antenna.

Its low power consumption characteristic is suitable to be used in this wearable unit. This module can be put in the sleep mode which requires only 3µA of current to run an active sleep timer. By using this mode in the design we can reduce the power consumption of the sensor node to prolong battery life.

The Coordinator… The microcontroller just simply calculate the number of heart beat per minute and sends this number to the coordinator. The coordinator is the main controller connected to the computer and it communicates directly with the sensing unit. The coordinator does not interpret the data, it just transmits and receives sampled analog and digital signals of the heart beats to the computer.

Computer and Database... A database is a collection of information that is organized so that it can easily be accessed, managed, and updated. A database consists of an organized collection of data for one or more uses, typically in digital form. The data sent to the database by zigbee transmitter is stored in the computer and it will be available for analysis in real time or in a later stage.

Advantages… It is a simple system to monitor heart rate continuously. Easy to use. Low power consumption. High degree of freedom in movement for patients who wear this device. Small size. Light weight.

Sample Plot… Fig: 6 - Sample plot of the analog and digital output signals from the monostable multivibrator circuit.

Conclusion…  Testing results proves the system successfully senses, collects and stores heart rate variability.  Using low power devices and clever design increase battery life on the sensor.  The database provides important information to analyze long term trends and patterns needed in the prevention of fall.

Future Scope… Range of the system can be increased by building a mesh wireless network. Using flexible PCB or SCB will further reduce size and weight of the sensor. Different wireless protocol such as ANT or Wibree will be investigated to further reduce power consumption since the amount of data transmission is very small. To simplify the device, the wireless link can be replaced with 1or 2GB mini-SD card.

Reference… Base paper: Bandage size non ECG heart rate monitor using Zigbee wireless link. Presented by Mr. Anh Dinh and Mr. Tao Wang at the 2010 IEEE international conference on Bioinformatics and Biomedical technology. Sites referred:

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