Monitoring health of a person continuously 24 hours a day and every day of the week is not easy for even doctors and researchers, unless the person is under care in a hospital or clinic. For a common person wishing to monitor his or her health in normal day to day life, it becomes even more difficult because most cardiac and other health monitors are not portable. These cannot be left attached to a person’s body whole day for continuous monitoring.
So, here is how you can design and make a small IoT-enabled monitor that you can stick to your body to capture your health data. It will capture data like heartbeat and body temperature in real time and show it on your phone or any other device that can be connected to Wi-Fi. It can be used anywhere to monitor the health parameters on a continuous basis. The author’s prototype is shown in Fig. 1.
Fig. 2 shows circuit diagram of the IoT health sticker, which is built around ESP12F (MOD1 ), MAX 301002 (MOD2), and MCP73812T (MOD3) ICs. The circuit has two parts—the IoT sensor battery charger (left side) and the IoT sensor sticker.
Fig. 2: The two parts of health sticker circuit
After connecting the components as per circuit diagram, interconnect the charger and sensor circuits. The charging circuit has battery connector JP1, which is connected to the IoT sensor chip circuit via switch S1. Connect the battery’s positive terminal through wire to pin 1 of JP1 and the negative terminal through another wire to the battery connector.
Fig. 3: Code for setting the Wi-Fi SSID and ESP server
Software
You need to prepare the code for IoT sticker and Arduino IDE. To install the Arduino IDE and ESP8266 board, open the library manager and install ESP-DASH and Sparkfun Max301x libraries. Include the Max3015 library and ESP-DASH in the code. Then set up the SSID and password of your phone Wi-Fi (hot spot) or home Wi-Fi. To be mobile you may use phone Wi-Fi, but if you want to monitor at home only you may use the home Wi-Fi.
Fig. 4: Code snippet for updating the sensor data in web dashboard
If you want to connect your phone to this monitoring device, you can set the Wi-Fi in STA mode. Set the cards’ names in the web page UI. You need to to show the heart rate, average heart rate, and body temperature data. So, create the cards for these to show in a web page hosted by ESP-DASH.
Components
Quantity
Description
ESP12F (MOD1 )
1
Wi-Fi MCU SMD chip
MAX 301002 (MOD2)
1
Health sensor module
MCP73812T (MOD3)
1
Cell charging SMD chip
LED1, LED2, LED3
3
SMD LED
4.7µF capacitor (C1, C2)
2
SMD capacitor
Resistor 100Ω (R1)
1
SMD resistor
Resistor 470Ω (R2)
1
SMD resistor
Resistor 2kΩ (R3)
1
SMD resistor
Slide switch (S1)
1
SPST slide switch
Jumper 2-pin male
1
Connector
3.3V battery
1
LiPo rechargeable
Now create the setup function and initialise the I2C connection with the Max sensor module and host the UI webpage. In the loop, check the sensor data and update it in the webpage UI cards. Put the ESP32 in programming mode and connect the ESP chip to FTDI. Select the ESP8266 board in Arduino IDE and select the right port and upload the source code healthtest.ino.
Construction and testing
After uploading the source code, solder all the components and connect the battery. Make a small, thin sticker using a sticking tape available at chemists for use on skin to stick it as shown in Fig. 5 and Fig. 6.
Fig. 5: Author’s prototype for the sticker with battery
Charge the device and slide the switch on the device to on position. You may now stick the IoT health monitor on your forearm or upper arm.
Fig. 6: The author using the device
Wait for the device to get connected and then search for the IP address in the browser. You should be able to see your health data on your phone or any other device you may have connected. Fig. 7 shows how the real-time data looks like.
Fig. 7: The device showing real-time health data
Bonus. A design with more functions and a market-ready PCB design is available on this link.
Monitoring health of a person continuously 24 hours a day and every day of the week is not easy for even doctors and researchers, unless the person is under care in a hospital or clinic. For a common person wishing to monitor his or her health in normal day to day life, it becomes even more difficult because most cardiac and other health monitors are not portable. These cannot be left attached to a person’s body whole day for continuous monitoring.
