I was cruising the Arduino forum and came across a situation where someone with ALS could not communicate with his friends due to complete paralysis. They were looking for a blink detector so he could blink Morse Code.

There are all kinds of complicated ways of detecting a blink but I wanted to try something simple so anyone can have a blink detector. So I made something based on a 20 cent component.

Works like a charm! Every time I blink a little light comes on. I suppose this could be made for 20 bucks of parts or so. You don’t have to make a pair of glasses the sensor can clamp to anything.

Update: I learned that Clinton the person the forum request was made for has passed away. “ALS is a monster”. — Clinton’s friend Wayne.

How It Works

It uses the TCRT5000 sensors (donated by Dave Hunt) for an Arduino contest we hosted for fun. The TCRT5000 is a 20 cent component.

It’s a distance sensor that uses infrared reflection. Your eyeball and eyelid will reflect IR light differently so blinking will trigger a quick reading change. I don’t think the LED gives off very much light so it should be okay to point towards the eyeball.

So I made up a quick circuit, a pair of plastic glass frames (3D print) and a quick Arduino program.

Applications

I think there’s a lot that could be done with blink detection.

I am making some masquerade masks that will have lights on them and was thinking that blink detection would be nice.

Related

Excerpt from Arduino forum post from June 27th, 2014.

My friend has ALS, locked in with only eye movements to communicate. After looking at many sites we bought a high tech Tobi PCeye tracking device but his breathing mask and glasses interfere too much.

We are both hams and learned Morse code years ago. We both have some years of experience with arduino and other electronics programs. All I need is a simple sensor to detect blinks…say left for dots and right for dashes. I could interface to a morse to text converter and display on the computer screen.

We are hurting here…I thought the other stages were bad but not being able to communicate is the worst. So I’m quite desperate. Anyone who has an idea, i’ve seen many sensors: strain gauges and IR sensors and even proximity switches on a guys eyelid…so much to try. Someone must have done this by now. Simple is the key. Must be minimally irritating of course.

Thank you.
Procyan

Excerpt from September 3rd, 2014 in Arduino thread:

Re: eye blink sensor

I am so grateful to all of you. I know this thread will be a help to others. I am certainly willing to contribute as much as I can.

ALS is a process…a monstrous terrible sequence. Yet somehow we found moments to enjoy, even to laugh. His philosophy was “as long as I’m still able to learn I will stay here.” But even that was taken eventually.

Gone now, but so much more important that he lived. If you are reading this because you or someone you know has a problem I promise to help how ever I can. If you don’t know this forum, I encourage you to join and open a thread. There are some top notch minds here, far more capable than mine, to draw upon.

Of all the things we tried, the IR sensors worked best. I would recommend following InventorArtist’s lead. It rides high and out of the way of all the other gear. Small, simple practical solution.

fight, Fight, FIGHT ALS

Here is the Arduino Code from my proof of concept.

/*
  blink detector
  darcy@inventorArtist.com
  
Blink Detection for ALS
 

  uses LED to detect blinking
  just looks for rising edges
  

*/
int sensorPin  = 0;        // IR Sensor
int ledPin = 13;           // Visualization
int lastLevel = 0;         // Previous IR level
int lastChange = 0;        // Change in IR level
int changeThreshold = 5;  // How hard a rising edge do we need?

//visualization
int duration = 100;        // Length of visualization
float lastStart = 0;       // Last start of visualization


void setup() {
  Serial.begin(9600);      // Debug constructor
  pinMode(13, OUTPUT);     // Visualizatio constructor
}
 
void loop() {
  int sensorValue = analogRead(sensorPin);Serial.println(sensorValue);  // Read Data
  // look for rising edges
  lastChange = sensorValue - lastLevel;
  lastLevel = sensorValue;
  if (lastChange >=changeThreshold) {
    digitalWrite(ledPin, HIGH);
    lastStart = millis();
  }
  if (millis() >= lastStart + duration) {
     digitalWrite(ledPin, LOW);
  }
  
  
  //absolute approach
  //if (sensorValue >=205) {
  //  digitalWrite(13, HIGH);
  //}else{
  //  digitalWrite(13, LOW);
  //}
  //delay(100);
}