BLOCK DIAGRAM

                               LIFI RECEIEVER                                                                  LIFI TRANSMITTER

WORKING 

The transmitter module is built around an ESP32 microcontroller which continuously reads physiological data from sensors — a MAX30102 sensor for heart rate and blood oxygen saturation (SpO2), and a DS18B20 sensor for body temperature. This data is processed in real-time and displayed optionally on an LCD for local monitoring. The ESP32 then encodes the sensor readings into a string format and transmits this data using a high-brightness LED as a LiFi light source. The LED rapidly flickers to send data through light pulses, which is invisible to the naked eye but can be detected by a photodiode.

The receiver module, implemented with an Arduino board, uses a photodiode or a similar light sensor to capture the LiFi light signals transmitted by the LED. These light pulses are converted back into electrical signals, which the Arduino reads via SoftwareSerial communication. The Arduino parses the received data string into individual health parameters — heart rate, SpO2, and temperature — and displays these readings clearly on a 16x2 LCD for monitoring. This system enables real-time, wireless, and secure transmission of vital health data without relying on traditional radio frequency communication, reducing electromagnetic interference and improving data privacy.

This setup is particularly useful in hospital environments or personal health monitoring where wireless RF signals may be limited or undesirable. The LiFi approach ensures a stable connection as long as there is line-of-sight between the transmitter LED and the receiver sensor, making it a promising technology for next-generation health monitoring applications.

• Data Collection:
  The transmitter ESP32 reads heart rate and SpO2 using the MAX30102 sensor and body temperature using the DS18B20 sensor.

• Data Processing:
  Sensor readings are processed and formatted into a string containing heart rate, SpO2, and temperature values.

• LiFi Transmission:
  The ESP32 sends the data through a high-brightness LED, which flickers at high speed to transmit the information as light pulses.

• Data Reception:
  The receiver Arduino uses a photodiode or light sensor to detect these light pulses and converts them into electrical signals.

• Data Decoding:
  The Arduino reads the incoming signals via SoftwareSerial, parses the data string, and extracts the health parameters.

• Display:
  Extracted data — heart rate, SpO2, and temperature — is displayed on a 16x2 LCD screen for monitoring.

• Wireless & Secure:
  Data transmission via LiFi avoids radio frequency interference and provides a secure line-of-sight communication channel.

• Applications:
  Useful in medical or sensitive environments where RF communication is restricted or not preferred.