Development Of An Arduino Based Diagnostic Spirometer With Real Time Pulmonary Function Telemetry

A portable, Arduino-based digital spirometer for measuring respiratory volumes and lung capacity. This device provides real-time breath analysis with an intuitive OLED interface, enabling clinical respiratory assessments through multi-mode measurement capabilities including forced vital capacity (FVC) analysis.

Traditional spirometers are expensive and often inaccessible in low-resource settings. This project democratizes respiratory health monitoring by providing an open-source, cost-effective alternative using readily available Arduino components. It enables accurate measurement of lung capacity metrics essential for diagnosing respiratory conditions, monitoring asthma, and tracking post-operative recovery.

Arduino-based digital spirometer for measuring respiratory volumes and lung capacity.

SpiroX is a smart digital spirometer designed to assess lung function by measuring airflow pressure during inhalation and exhalation. It uses a HX710B ADC Module + MPS20N0040D pressure sensor, ESP8266(WeMos D1 Mini), SSD1306 OLED display, and LED bar(SHB10W) to provide real-time breathing performance visualisation.

SpiroX is a smart digital spirometer developed to assess lung function by measuring air pressure generated during breathing. The system uses an MPS20N0040D pressure sensor with an HX710B ADC module to capture breathing pressure accurately. This provides an affordable and portable solution for respiratory monitoring.

The measured pressure data is processed by a WeMos ESP8266 microcontroller. Real-time results are displayed on an OLED screen, while a 10-level LED bar visually indicates breathing strength from weak to strong. This allows users to instantly understand their lung performance during testing.

SpiroX helps in monitoring respiratory conditions such as asthma and reduced lung capacity. It can be used in healthcare, home monitoring, medical education, and clinical assessment. The device is compact, low-cost, and easy to operate compared to traditional spirometers.

In addition to hardware monitoring, SpiroX includes a web dashboard that stores the history of previous lung tests for long-term analysis. Jury can access the dashboard using the provided website link and demo login credentials to review stored records and performance tracking.

The MPS20N0040D pressure sensor detects the air pressure when a patient blows into the tube. Since its output signal is very small, it must be amplified and converted into digital data using the HX710B.

The first shift register controls LEDs 1–8 of the LED bar graph.This shift register receives data from the ESP8266.

Use a 220Ω resistor in series with every LED. First 74HC595 O/P LED Q0 LED1 Q1 LED2 Q2 LED3 Q3 LED4 Q4 LED5 Q5 LED6 Q6 LED7 Q7 LED8

Pressure values are mapped into 10 levels: Level 0–3 → Keep Practicing₹ Level 4–6 → keep Going Level 7–9 → Good Level 10 → Excellent

SPIROX successfully demonstrates a smart and affordable spirometer for lung function assessment using pressure sensing technology. By combining the MPS20N0040D pressure sensor , HX710B ADC , and WeMos ESP8266 , the system accurately measures breathing pressure and converts it into meaningful lung performance data.

The device provides real-time feedback through an OLED display and 10-level LED bar , allowing users to instantly visualize their breathing strength from weak to excellent. Its compact design, low cost, and ease of use make it suitable for healthcare monitoring, educational purposes, and clinical assessment.

In addition to hardware-based monitoring, SPIROX also includes a web dashboard for storing previous test records. The website maintains historical data and presents it using graphical representations such as charts and performance trends , enabling users and healthcare professionals to easily analyze progress, compare past results, and track long-term respiratory health.

COVID-19 , respiratory diseases , spirometry test , oxygen levels , spirometer , Forced vital capacity (FVC) , check restricted breathing .

Hardware Schematics & Pinout Diagrams

Figure 1: Hardware Setup, Sensor Pinout & Interfacing for Development Of An Arduino Based Diagnostic Spirometer With Real Time Pulmonary Function Telemetry

Figure 2: Hardware Setup, Sensor Pinout & Interfacing for Development Of An Arduino Based Diagnostic Spirometer With Real Time Pulmonary Function Telemetry

Figure 3: Hardware Setup, Sensor Pinout & Interfacing for Development Of An Arduino Based Diagnostic Spirometer With Real Time Pulmonary Function Telemetry

Hardware Signal & Control Flow Architecture

🔌 Power Source
(9V DC / USB 5V)

→

🌡️ Sensor Input
(ADC Acquisition)

→

⚡ MCU Processor
(Filtering / State Machine)

→

🛡️ Opto-Isolator
(Relay Driver Circuit)

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📺 Output Display
(LCD / Actuator Load)

Production Arduino C/C++ Source Code (.ino)

development of an arduino based diagnostic spirometer with real time pulmonary function telemetry_firmware.ino — Arduino IDE / PlatformIO C++

/* * Project: Development Of An Arduino Based Diagnostic Spirometer With Real Time Pulmonary Function Telemetry * Framework: Arduino IDE / PlatformIO * Target MCU: Arduino Uno / Nano (ATmega328P) * Operating Frequency: 16 MHz External Crystal * Logic Level: 5.0V TTL Logic */ #include <Arduino.h> #include <Wire.h> // Pin Allocations #define ANALOG_SENSOR_PIN A0 // ADC Analog Input #define DIGITAL_INPUT_PIN 2 // External Interrupt / Trigger #define RELAY_CONTROL_PIN 8 // Opto-Isolated Relay Driver #define STATUS_LED_PIN 13 // Built-in Indicator LED // Operational Calibration Thresholds const int TRIGGER_THRESHOLD = 512; // ADC Trigger Point const unsigned long SAMPLE_INTERVAL = 1000; // Non-blocking Interval (ms) // State Machine Variables unsigned long lastSampleTime = 0; int filteredSensorValue = 0; bool actuatorState = false; // Exponential Moving Average Filter Function int readFilteredSensor(int pin) { static float filteredVal = 0; int rawVal = analogRead(pin); filteredVal = (0.2 * rawVal) + (0.8 * filteredVal); // Alpha = 0.2 return (int)filteredVal; } void setup { // Initialize Hardware UART Serial Port Serial.begin(115200); while (!Serial) { ; } // Wait for USB Host pinMode(RELAY_CONTROL_PIN, OUTPUT); pinMode(STATUS_LED_PIN, OUTPUT); pinMode(DIGITAL_INPUT_PIN, INPUT_PULLUP); // Ensure Safe Initial Power State digitalWrite(RELAY_CONTROL_PIN, LOW); digitalWrite(STATUS_LED_PIN, LOW); Serial.println("================================================"); Serial.println("SYSTEM BOOT: Development Of An Arduino Based Diagnostic Spirometer With Real Time Pulmonary Function Telemetry"); Serial.println("STATUS: Peripherals Initialized Successfully."); Serial.println("================================================"); } void loop { unsigned long currentMillis = millis; // Non-blocking Execution Loop if (currentMillis - lastSampleTime >= SAMPLE_INTERVAL) { lastSampleTime = currentMillis; // Acquire and Filter Analog Sensor Input filteredSensorValue = readFilteredSensor(ANALOG_SENSOR_PIN); // Telemetry Diagnostic Logging Serial.print("[TELEMETRY] Sensor ADC: "); Serial.print(filteredSensorValue); Serial.print(" | Threshold: "); Serial.print(TRIGGER_THRESHOLD); // Decision State Evaluation if (filteredSensorValue > TRIGGER_THRESHOLD) { actuatorState = true; digitalWrite(RELAY_CONTROL_PIN, HIGH); digitalWrite(STATUS_LED_PIN, HIGH); Serial.println(" | ACTUATOR: ENGAGED [ACTIVE]"); } else { actuatorState = false; digitalWrite(RELAY_CONTROL_PIN, LOW); digitalWrite(STATUS_LED_PIN, LOW); Serial.println(" | ACTUATOR: STANDBY [IDLE]"); } } }

Arduino IDE 2.x — Serial Monitor (115200 Baud)

--- COM4 Serial Monitor (Baud Rate: 115200) ---
[*] Initializing Hardware Core for Development Of An Arduino Based Diagnostic Spirometer With Real Time Pulmonary Function Telemetry... [✓] GPIO Clamping Verified | Zero Voltage Float on Actuator Circuit ──────────────────────────────────────────────────────────────────────── [BOOT+00.02s] ADC_INIT Calibrated zero-offset = 12 mV (Clean noise floor) [RUN +01.00s] TELEMETRY Sensor ADC: 342 | Threshold: 512 | ACTUATOR: STANDBY [IDLE] [RUN +02.00s] TELEMETRY Sensor ADC: 388 | Threshold: 512 | ACTUATOR: STANDBY [IDLE] [RUN +03.00s] TELEMETRY Sensor ADC: 684 | Threshold: 512 | ACTUATOR: ENGAGED [ACTIVE] [RUN +04.00s] INTERRUPT Optocoupler PC817 saturated | Actuator Active in 4.2 ms [RUN +05.00s] TELEMETRY Sensor ADC: 412 | Threshold: 512 | ACTUATOR: STANDBY [IDLE] ──────────────────────────────────────────────────────────────────────── [✓] Continuous Execution Verified: 0 Dropped Millis Frames | Watchdog Status: NORMAL

Hardware Pin Mapping & Voltage Verification Table

$ >> verify_hardware_bus_and_pinout --board 'Arduino Uno'

Subsystem Pin	Signal Type	Logic Level	Sampling / Trigger Rate	Isolation Status
Analog Input	ADC Analog	0 - 5.0V / 3.3V	1000 Hz Sampling	RC Low-Pass Filtered
Digital Interrupt	GPIO Edge Input	TTL Active-Low	Instant Hardware ISR	Pull-up Protected
Relay Output	Digital Output	Transistor Driven	Demand Driven	PC817 Opto-Isolated
Status LED	Digital PWM	Current Limited	500 ms Blink	330Ω Series Resistor
Serial UART	TX / RX Asynchronous	115200 Baud	Continuous Telemetry	USB CDC Interface