Medical Devices Lab

Exp no 1: Observation of Different Temperature Sensors (IR sensor, DHT11) with Arduino.

Objective: To compare the performance Infrared (IR) temperature sensor and a DHT11 temperature and humidity sensor using an Arduino microcontroller.

Components/Devices Used: 


DHT11 Sensor: The DHT11 sensor measures both temperature and humidity. It contains a thermistor for temperature measurement and a capacitive humidity sensor for humidity measurement. The sensor outputs a digital signal on the data pin. 

IR Temperature Sensor: The IR sensor, such as the MLX90614, is a non-contact thermometer that uses infrared radiation to measure temperature. It detects infrared energy emitted by objects and calculates their temperature based on the amount of IR energy emitted.

Circuit for  DHT11

Circuit for IR Temperature Sensor

Arduino code for DHT11:

#include <dht.h>  // Include library

#define outPin 7  // Defines pin number to which the sensor is connected

dht DHT;      // Creates a DHT object

void setup() {



void loop() {

  int readData = DHT.read11(outPin);

  float t = DHT.temperature;  // Read temperature

  float h = DHT.humidity;   // Read humidity

  Serial.print("Temperature = ");


  Serial.print("°C | ");

  Serial.print((t*9.0)/5.0+32.0); // Convert celsius to fahrenheit

  Serial.println("°F ");

  Serial.print("Humidity = ");


  Serial.println("% ");


  delay(2000); // wait two seconds


Arduino code for IR Sensor:

#include <Wire.h>

#include <Adafruit_MLX90614.h>

Adafruit_MLX90614 mlx = Adafruit_MLX90614();

void setup() {


  Serial.println("Adafruit MLX90614 test");  



void loop() {

  Serial.print("Ambient = "); Serial.print(mlx.readAmbientTempC()); 

  Serial.print("*C\tObject = "); Serial.print(mlx.readObjectTempC()); Serial.println("*C");

  Serial.print("Ambient = "); Serial.print(mlx.readAmbientTempF()); 

  Serial.print("*F\tObject = "); Serial.print(mlx.readObjectTempF()); Serial.println("*F");





Output of the DHT11 sensor

Circuit for  DHT11

Output of the IR Temperature  sensor

Circuit for IR Temperature Sensor

Exp No 2: Understanding Corneal Curvature: A Practical Approach with Keratometer.

Objective: To learn how to use a keratometer for measuring the curvature of the cornea and understand its implications in diagnosing and correcting refractive errors.

Anatomy of Eye

The Role of Corneal Curvature in Vision 

The cornea's curvature is pivotal in bending (refracting) light rays to focus them on the retina. The degree of curvature determines how effectively the eye can focus light. If the curvature is not ideal, it leads to refractive errors, meaning the light doesn't focus perfectly on the retina, affecting the clarity of vision. 

Common Refractive Errors Related to Corneal Shape 

Principles of Keratometry 

Keratometry is a technique used to measure the curvature of the anterior (front) surface of the cornea. 


In a simplified model, if you have the refractive power (D) of the cornea and the refractive index (n), you can use the formula,   

D= (n - 1)/r

where, r is the radius of curvature,  n is the refractive index of the cornea relative to air.




R1: Usually corresponds to the flatter (or least curved) meridian. 

R2: Usually corresponds to the steeper (or more curved) meridian.

Exp no 3: EEG Exploration Using Emotiv Device


Materials used:


Electroencephalography (EEG) is a method to record electrical activity of the brain. It involves placing electrodes on the scalp, which pick up electrical signals produced by brain cells (neurons) communicating with each other.

The brain's electrical activity is always changing, and these changes reflect different mental states and processes. EEG captures these variations in voltage, allowing us to see brainwave patterns.


Nature of Brainwaves: Brainwaves are patterns of neuronal activity in the brain. They are crucial for understanding brain function and are associated with different states of consciousness, like sleep, relaxation, alertness, and problem-solving.

Significance: Analyzing these waves helps in understanding various brain disorders, mental states, and cognitive processes. It's key in diagnosing conditions like epilepsy, sleep disorders, and brain injuries.

Different Frequency Bands:

Delta Waves (<4 Hz):

 Characteristics:  Slowest brainwaves, high amplitude.

 Associated With: Deep, dreamless sleep, and unconsciousness.

 Significance: Important in healing and regeneration.

Theta Waves (4-7 Hz):

Characteristics: Found between sleep and wakefulness.

 Associated With: REM sleep, meditation, creativity, and memory formation.

 Significance: Often linked with emotions and subconscious mind.

Alpha Waves (8-13 Hz):

 Characteristics: Present in relaxation, light meditation.

  Associated With: Relaxed but awake state, often with closed eyes.

  Significance: Important for stress reduction, well-being, and overall mental coordination.

Beta Waves (13-30 Hz):

Characteristics: Dominant during waking state, particularly active thinking, problem-solving.

Associated With: Alertness, concentration, cognition.

Significance: Vital for engaged mental activity, but high levels may indicate anxiety or restlessness.

Gamma Waves (>30 Hz):

 Characteristics: Highest frequency, low amplitude.

 Associated With: High-level information processing, insight, consciousness.

 Significance: Crucial for cognitive functioning, learning, and memory.