Basic Electronics for Beginners: Portable Pulse Oximeter using Arduino Nano

1. Introduction

A Portable Pulse Oximeter using Arduino is a compact device used to measure:

Blood Oxygen Saturation (SpO₂)
Heart Rate (BPM)

It works using a MAX30100/MAX30102 sensor, which emits red and infrared light through the fingertip and measures absorption changes due to blood flow.

This project is ideal for:

Biomedical electronics learning
IoT healthcare projects
Student demonstrations

2. Components

Arduino Nano / Uno
MAX30100 or MAX30102 Pulse Oximeter Sensor
OLED Display (SSD1306 I2C, 128x64)
Lithium-ion Battery (3.7V)
TP4056 Charging Module
MT3608 Boost Converter
Connecting wires
Breadboard / PCB

3. Circuit and Connections

Arduino Nano Pinout Diagram

Pinout Diagram MAX30102 Sensor

Pinout Diagram of OLED Display SSD1306

TP4056 Pinout Diagram

🔹 MAX30102 Sensor → Arduino

VCC → 3.3V
GND → GND
SDA → A4
SCL → A5

🔹 OLED Display → Arduino

VCC → 5V
GND → GND
SDA → A4
SCL → A5

👉 Both devices use I2C communication, so they share the same SDA and SCL pins.

🔹 Power Section

Battery → TP4056
TP4056 → Boost Converter
Boost Converter → Arduino VIN (5V)

4. Detailed Step By Step Circuit Working

When power is supplied, Arduino initializes the sensor and OLED display.
The MAX30102 emits red and infrared light into the finger.
Blood absorbs light differently based on oxygen level.
The photodetector captures reflected light signals.
Sensor converts signals into digital values via I2C.
Arduino processes the data using an algorithm.
Heartbeat is detected from waveform peaks → BPM calculated.
Ratio of red/IR signals → SpO₂ calculated.
Results are displayed on OLED screen in real time.

5. Libraries to be Included

Install from Arduino Library Manager:

Adafruit GFX
Adafruit SSD1306
MAX30100lib or SparkFun MAX3010x

6. Code


#include <Wire.h>
#include "MAX30100_PulseOximeter.h"
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);
PulseOximeter pox;

uint32_t tsLastReport = 0;

void setup()
{
    Serial.begin(9600);

    if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
        Serial.println("OLED failed");
        for(;;);
    }

    display.clearDisplay();

    if (!pox.begin()) {
        Serial.println("Sensor failed");
        for(;;);
    }

    pox.setIRLedCurrent(MAX30100_LED_CURR_7_6MA);
}

void loop()
{
    pox.update();

    if (millis() - tsLastReport > 1000) {
        display.clearDisplay();

        display.setTextSize(2);
        display.setTextColor(WHITE);

        display.setCursor(0,0);
        display.print("BPM:");
        display.println(pox.getHeartRate());

        display.setCursor(0,30);
        display.print("SpO2:");
        display.print(pox.getSpO2());
        display.println("%");

        display.display();

        tsLastReport = millis();
    }
}

7. Detailed Step By Step Code Working

#include <Wire.h> → Enables I2C communication
MAX30100_PulseOximeter.h → Sensor control library
OLED libraries → Display control

Setup Function

Initializes OLED display
Starts pulse oximeter sensor
Sets LED current for stable readings

Loop Function

pox.update() → Continuously reads sensor data
Every 1 second:
- Clears display
- Reads BPM using getHeartRate()
- Reads SpO₂ using getSpO2()
- Displays results

8. Tips

Keep finger steady for accurate readings
Use 3.3V for MAX30102 (very important)
Avoid bright external light interference
Ensure proper finger placement
Use filtering if readings fluctuate

9. Uses

Health monitoring systems
Fitness tracking devices
Biomedical projects
Remote patient monitoring
IoT healthcare applications

10. Conclusion

This Arduino-based Portable Pulse Oximeter is a powerful project combining sensor technology, signal processing, and display interfacing. It is compact, low-cost, and highly useful for educational and prototype healthcare applications.

You can further enhance it by adding:

Bluetooth/WiFi connectivity
Data logging (SD card)
Alert systems for abnormal readings

Portable Pulse Oximeter using Arduino Nano